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| TEXT BOOK of MEDICINE |
Section XXVIII Skin Diseases
| 464 ECZEMAS, PHOTODERMATOSES, PAPULOSQUAMOUS (INCLUDING FUNGAL) DISEASES, AND FIGURATE ERYTHEMAS Henry W. Lim • |
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▪ECZEMA
The more commonly encountered eczemas (Table 464-1) share similar histologic characteristics. However, they have varying degrees of edema within the epidermis (spongiosis) and of infiltration with lymphocytes and macrophages in the superficial dermis.
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▪Nummular Dermatitis
Nummular dermatitis occurs most frequently in patients who are in their 50s to 60s and is usually associated with significant dryness of the skin (xerosis). Both sexes are affected; in temperate climates, this condition is most frequently seen in the winter. The condition appears to be more frequent among Asians. The origin of nummular dermatitis is unclear, although xerosis plays a significant role in its pathogenesis.
Patients usually present with pruritic, coin-shaped, erythematous patches with some scales and occasionally with pinhead-sized vesicles (Fig. 464-1). Lesions may be excoriated and lichenified (i.e., thickened skin with accentuation of skin markings). Legs and arms are the commonly affected sites, although lesions can also occur on the trunk. All patients should be educated about the care of dry skin, such as the use of emollients and moisturizing soaps and avoidance of long, hot showers. Topical corticosteroid ointments (e.g., triamcinolone ointment, 0.1% twice daily for 1 to 2 weeks) are helpful for active lesions, and oral antihistamines (e.g., fexofenadine, 180 mg every morning, and hydroxyzine, 25 to 50 mg at bedtime, as needed) are useful for pruritus. In severe cases, narrow-band ultraviolet B (NB-UVB) phototherapy, psoralen combined with UVA (PUVA), or a short course of oral corticosteroids (prednisone, 0.5 to 1 mg/kg/day, with a maximum dose of 60 mg/day, for 1 to 2 weeks, then taper in 10 to 14 days) is beneficial.
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| FIGURE 464-1 Coin-shaped erythematous patches in a patient with nummular dermatitis. |
▪Dyshidrosis
Dyshidrosis appears as deep-seated, pinhead-sized vesicles, most commonly along the sides of the fingers (Fig. 464-2). Occasionally, the palms and soles may also be involved. Lesions are usually pruritic, associated with xerosis of the surrounding skin. Fissuring of the tip and the side of the fingers frequently occurs. Dyshidrosis is seen in individuals who wash their hands frequently, such as health care and restaurant workers and mothers of young infants. Treatment follows a sequential order: (1) minimizing of hand washing, (2) liberal use of over-the-counter emollients, (3) topical corticosteroid ointments (e.g., fluocinonide ointment, 0.05% twice daily for 2 weeks), and (4) oral antihistamines (e.g., fexofenadine, 180 mg every morning, and hydroxyzine, 25 to 50 mg at bedtime, as needed).
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| FIGURE 464-2 Dyshidrosis. A, Scaly erythematous patch with erosions on the side of a finger. B, Erythema, scaliness, and peeling of the palm. |
▪Atopic Dermatitis
Atopic dermatitis is most commonly seen among young children, but severe cases persist into adulthood. In more than 80% of the patients, the disease starts before the age of 5 years. The prevalence has been estimated at between 15 and 23%. Patients usually present with xerosis, erythematous scaly patches, small vesicles, excoriations, crusting, and, not infrequently, impetiginization (Fig. 464-3). With chronic scratching and rubbing, hyperpigmentation and lichenification occur. Commonly affected sites include the periorbital area and flexor areas such as the neck, antecubital fossa, and popliteal fossa. In severe cases, the entire skin surface may be involved. Diagnosis is made by the typical morphologic features and by the distribution of the lesions, as well as by a family and personal history of atopy. The therapeutic ladder consists of the following: (1) over-the-counter emollients; (2) topical corticosteroid ointments (e.g., triamcinolone ointment, 0.1% twice daily for 1 to 2 weeks), or topical calcineurin inhibitors (tacrolimus ointment, 0.1% for 3 to 4 weeks, or pimecrolimus cream, 1% for 3 to 4 weeks).1 2 The latter have been given a “black box warning” by the U.S. Food and Drug Administration for their potential association with the development of malignant disease; therefore, continuous prolonged use (i.e., >2 to 3 months) should be minimized; (3) oral antihistamines (e.g., fexofenadine, 180 mg every morning, and hydroxyzine, 25 to 50 mg at bedtime, as needed); (4) NB-UVB phototherapy3; and (5) PUVA. In patients with recalcitrant cases, oral prednisone (0.5 to 1 mg/kg/day), cyclosporine (3 to 5 mg/kg/day), and mycophenolate mofetil (1 to 2 g/day) have been successful.
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| FIGURE 464-3 Atopic dermatitis. Note the erythema, excoriation, and lichenification. |
▪Seborrheic Dermatitis
Seborrheic dermatitis is a common condition that occurs as erythematous patches with fine, greasy-appearing scales, most commonly on the malar area, midforehead, midchest, and scalp (Fig. 464-4). This condition is common in patients with human immunodeficiency virus (HIV) infection (Chapter 415). The pathogenesis is unknown, although Pityrosporum ovale is believed to play a role. The diagnosis can usually be made on clinical grounds alone. Topical corticosteroids (e.g., hydrocortisone cream 2.5%, twice daily for 1 to 2 weeks) can rapidly reduce the inflammation; then topical ketoconazole cream, 2% twice daily as needed (or shampoo 2% daily or every other day for the scalp), is safe for long-term treatment.
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| FIGURE 464-4 Erythematous patches with greasy-appearing scales on the malar area of two patients with seborrheic dermatitis. |
▪Allergic Contact Dermatitis and Irritant Contact Dermatitis
Allergic contact dermatitis and irritant contact dermatitis are induced by exogenous agents. Allergic contact dermatitis is a delayed hypersensitivity response to external allergens, whereas irritant contact dermatitis is a nonspecific toxic response to contact irritants. In both conditions, lesions occur in the exposed area, but in patients with severe cases, nonexposed areas may also have milder lesions. In allergic contact dermatitis, patients present with erythematous pruritic papules followed by vesicles. Lesions resolve with fine scales. Postinflammatory hyperpigmentation may be observed, especially in dark-skinned individuals. Histologically, epidermal edema and dermal histiocytic infiltrates are observed. Irritant contact dermatitis manifests with lesions morphologically similar to those of allergic contact dermatitis. However, irritant contact dermatitis is usually associated with a burning sensation rather than with pruritus. Postinflammatory hyperpigmentation is frequently observed. Histologic changes consist of necrotic keratinocytes, epidermal necrosis, and neurophilic infiltrates. Management includes identification and removal of the offending agent, as well as symptomatic treatments such as topical corticosteroids and oral antihistamines.
▪PHOTODERMATOSES
Photodermatoses indicate the development of cutaneous eruption secondary to exposure to UV or visible radiation (Table 464-2). By convention, electromagnetic radiation in the UV region is divided into UVC (200 to 290 nm), UVB (290 to 320 nm), UVA-2 (320 to 340 nm), and UVA-1 (340 to 400 nm). Visible light extends from 400 to 760 nm. Because UVC emitted by the sun is absorbed by ozone in the stratosphere, UVC does not reach the Earth's surface. UVB, UVA, and visible light are the relevant spectra in photodermatoses.
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▪Polymorphous Light Eruption
Polymorphous light eruption, the most common idiopathic photodermatosis, occurs in 10 to 20% of the general population. It usually occurs in young adults, has a slight female predominance, and is seen worldwide. Affected individuals are less susceptible to cutaneous photoimmunosuppression and hence have an enhanced response to UV-induced neoantigens in the skin. Lesions usually occur in early spring within a few hours of exposure to sunlight. Lesions can manifest as pinhead papules, papules, papulovesicles, or, less commonly, vesicles (Fig. 464-5); they can also be minimally pruritic. Usually, lesions persist for several days and resolve spontaneously. The condition tends to improve as the sunny season progresses, a phenomenon known as “hardening.”
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| FIGURE 464-5 Erythematous papules a few hours after exposure to the sun in a patient with polymorphous light eruption. |
The course is chronic; only 11% of patients have complete resolution of the disease in 16 years and 24% in 32 years. Diagnosis is based on the typical history and morphologic features of the lesion; the diagnosis can be confirmed by the induction of lesions with provocative phototesting. When lesions occur primarily on the face, a diagnosis of lupus must be excluded. Management consists of sun avoidance, the use of broad-spectrum sunscreens, topical corticosteroids, and oral antihistamines. In severe cases, desensitization treatment using NB-UVB or PUVA has been successful. Desensitization is usually performed in early spring by exposing patients to increasing doses of NB-UVB or PUVA.
▪Chronic Actinic Dermatitis
Chronic actinic dermatitis is a chronic photodermatosis that occurs most commonly in men in their 60s and 70s. It has been seen in patients of all ethnic groups, but in the United States, it is more commonly seen in dark-skinned individuals. It occurs in 5 to 17% of patients referred for evaluation of photosensitivity. Chronic actinic dermatitis can evolve from photoallergic contact dermatitis, allergic contact dermatitis, or exposure to a known photosensitizing agent; however, it can also arise de novo. Investigators have postulated that this condition represents a delayed hypersensitivity response to an unidentified antigen.
Patients present with erythematous papules and plaques with superficial scaling and, frequently, with lichenification (Fig. 464-6). The distribution of lesions is primarily on sun-exposed areas, such as the forehead, nose, cheeks, “V” area of the neck, dorsum of the hands, and forearms. Typically, sun-protected areas, such as the postauricular area, the area underneath the chin, the area above the eyes, and the trunk, are spared. This chronic photosensitivity occurs in the absence of any continued exposure to known photosensitizers. Histologically, one sees a dermal lymphohistiocytic infiltrate; atypical mononuclear cells may be observed. On phototesting, patients have decreased sensitivity to UVA, UVB, and/or visible light. In a study of 178 cases, 10% resolved in 5 years and 50% in 15 years. An association with HIV infection (Chapter 415) has been reported.
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| FIGURE 464-6 Erythema and lichenification in a patient with chronic actinic dermatitis. Note sparing of the sun-protected areas of the neck, infra-auricular area, and lower cheeks. |
The diagnosis is based on the patient's history and on the morphologic features and distribution of the lesions. It is confirmed by phototesting.
Management is challenging. During the sunny season, it is critical that patients practice maximal photoprotection, consisting of staying in the shade, using broad-spectrum sunscreens, clothing, and wearing a wide-brimmed hat. Other treatment modalities, in approximate sequential order, are topical tacrolimus ointment, oral mycophenolate mofetil (1 to 2 g/day), oral cyclosporine (3 to 5 mg/kg/day), and azathioprine (50 to 200 mg/day). In recalcitrant cases, the following may be used: PUVA in conjunction with oral corticosteroids or a combination of mycophenolate mofetil, PUVA, and oral corticosteroids.
▪Solar Urticaria
Solar urticaria occurs worldwide. In photodermatology referral centers, it accounts for 5 to 7% of patients. The mean age at onset is usually in the fourth decade, with a slight female predominance. In one study, the mean duration of disease at the time of diagnosis was 3.6 years. Patients develop urticaria that appears within minutes of sun exposure and persists for less than 24 hours. Lesions are most commonly induced by visible light, but they can also be induced by UVA or UVB. Similar to polymorphous light eruption, improvement may occur as the summer season progresses (hardening). The diagnosis is confirmed by induction of the lesion after controlled exposure to the appropriate light source. Management consists of photoprotection and the use of oral antihistamines (e.g., fexofenadine, 180 mg every morning, and hydroxyzine, 25 to 50 mg at bedtime). In severe cases, graduated exposure to UVA or PUVA is helpful.
▪Phototoxicity and Photoallergy
The terms phototoxicity and photoallergy refer to the development of skin lesions after combined exposure to an oral or topical photosensitizer and electromagnetic radiation. Phototoxicity is a nonspecific cutaneous toxic reaction, whereas photoallergy is a delayed hypersensitivity response. For most photosensitizers, the action spectrum for both lies in the UVA range. Most of the phototoxic agents are systemic medications, whereas the most common photoallergens are the various ultraviolet filters in sunscreen. In both conditions, patients present with erythematous papules and vesicles confined to sun-exposed areas. Vesicular eruption is distinctly more common in phototoxicity, whereas pruritic eczematous eruption is more common in photoallergy. Histologically, phototoxicity is characterized by necrotic keratinocytes and infiltrates consisting predominantly of neutrophils, whereas photoallergy is characterized by epidermal edema (spongiosis) and lymphohistiocytic dermal infiltrate. The diagnosis is based on a careful history for exposure to photosensitizers combined with the typical morphologic features. Management consists of identification and removal of photosensitizer and the use of topical corticosteroids (e.g., triamcinolone ointment, 0.1% twice daily for 2 weeks) and oral antihistamines (e.g., fexofenadine, 180 mg every morning, and hydroxyzine, 25 to 50 mg at bedtime as needed (Chapter 463).
▪Porphyrias
The most common cutaneous porphyria is porphyria cutanea tarda, in which patients present with skin fragility and blister formation on sun-exposed areas, most commonly the dorsum of the hands and the forearms (Fig. 464-7; Chapter 229). Erosion and crusting on the face can also be noted. Patients usually have periorbital hypertrichosis and, less frequently, periorbital mottled hyperpigmentation and hypopigmentation. Sclerodermoid skin changes can occur in both sun-exposed and sun-protected areas. The defective enzyme is uroporphyrinogen decarboxylase. Porphyria cutanea tarda is associated with excessive alcohol intake, exposure to estrogens, hepatitis C infection (Chapter 152), HIV infection (Chapter 415), and hemochromatosis (Chapter 231). Patients invariably have an elevated level of ferritin and frequently have elevated liver enzyme values.
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| FIGURE 464-7 Erosion, crusting, and vesicles on the dorsum of the hand of a patient with porphyria cutanea tarda. |
The diagnosis is suggested by the typical clinical appearance and is confirmed by the characteristic porphyrin profile (elevated levels of 8-, 7-, 6-, 5-, and 4-carboxyl porphyrins in the urine and isocoproporphyrin in feces; Chapter 229). Management consists of avoidance of precipitating factors (alcohol, iron-containing vitamins, estrogen-containing birth control pills) and weekly phlebotomy. In patients who are anemic (e.g., those with HIV infection), low-dose hydroxychloroquine (200 mg/week) is beneficial. With appropriate treatment, remission can persist for years.
PAPULOSQUAMOUS (INCLUDING FUNGAL) DISEASES
Common papulosquamous diseases are listed in Table 464-3.
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▪Psoriasis
Epidemiology
Psoriasis is the most commonly recognized papulosquamous disease. It occurs in 2 to 3% of the general population, with considerable variation in different parts of the world. It affects male and female patients equally. Approximately one third of the patients have a positive family history. Psoriasis has bimodal peak of onset, at age 22.5 years and again at age 55 years. The onset of psoriasis before the age of 15 years is associated with a higher prevalence of positive family history of psoriasis and with more severe disease.
Pathobiology
Psoriasis was initially thought to be purely a disease of keratinocyte hyperproliferation; however, it has now clear that it is an immunologically mediated disease. Factors playing a role in the pathogenesis include T cells, cytokines, chemokines, growth factors, dendritic cells, eicosanoids, neutrophils, and mast cells. Investigators have postulated that, in genetically susceptible individuals, exposure to precipitating factors such as infections (e.g., streptococcal or HIV infections), stress, or physical injury results in activation of T cells and generation of cytokines, followed by influx of neutrophils and subsequent release of inflammatory mediators, which lead to the development of cutaneous lesions.
A linkage disequilibrium (i.e., higher than expected association) occurs between psoriasis and human leukocyte antigens (HLAs), the most common being HLA-Cw6. However, HLA-Cw6 is unlikely to be the disease allele, because psoriasis develops in only about 10% of HLA-Cw6–positive individuals. PSORS1, mapped to chromosome 6p21.3, is now considered a major locus for susceptibility to psoriasis.
Clinical Manifestations
Psoriasis can involve the skin, scalp, and nails. Skin lesions are characterized by erythematous macules, papules, or plaques that are usually covered with silvery scales (Fig. 464-8). On removal of the scales, pinpoint bleeding may be observed (the Auspitz sign), a finding reflecting the proliferation of blood vessels in the superficial dermis. Nail involvement includes pittings, yellowish macules underneath the nail plate (“oil drop” sign), and thickening of the nail (onychodystrophy) (Fig. 464-9). Minor injury to the skin can result in the development of psoriatic lesions (Koebner's phenomenon). The association of psoriasis with HIV infection (Chapter 415) has been well documented; HIV-associated psoriasis tends to be inflammatory and is usually more resistant to treatment compared with non–HIV-associated psoriasis.
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| FIGURE 464-8 Erythematous plaques with silvery scales in a patient with psoriasis. |
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| FIGURE 464-9 Thickening and crumbling of the nail plate (onychodystrophy) in a patient with psoriasis. Note the erythematous patches with silvery scales in the periungual area. |
Several distinct forms of psoriasis are recognized. Psoriasis vulgaris, the most common type, appears as a persistent erythematous scaly papule and plaque on elbows, knees, and scalp; however, it may also involve any part of the body. Guttate psoriasis usually occurs after viral or bacterial (most commonly streptococcal) infection; it appears as small, erythematous, scaly papules scattered over a large area of the body in a raindrop distribution (guttate = droplike). Inverse psoriasis refers to psoriasis that occurs in skinfold areas such as the groin, axilla, and inframammary folds. It appears as an erythematous, somewhat shiny patch; because of the constant friction in the involved areas, scales are usually absent. Erythrodermic psoriasis appears as widespread, sometimes generalized erythroderma with fine silvery scales, frequently associated with fissures. Palmoplantar psoriasis manifests as keratotic scaly patches and plaques on the palms and soles, very frequently with accompanying fissures, which can be painful. Pustular psoriasis of von Zumbusch is a rare variant of psoriasis occurring with generalized pustules that are 2 to 3 mm in diameter and associated with the onset of fever.
Five to 30% of patients with psoriasis may also have psoriatic arthritis, which may precede that appearance of cutaneous lesions (Chapter 286). Most of these patients present with peripheral asymmetrical oligoarthritis involving the interphalangeal joints of the hands and feet, the large joints of the legs, or combinations of both. Psoriatic arthritis has been associated with HLA-B57, although some studies have also reported HLA-Cw6 in more than 50% of all persons with this disease.
Diagnosis
In most cases, the diagnosis of psoriasis can be made based on the history and physical examination alone. However, in patients with erythrodermic psoriasis, other causes of generalized erythroderma (including pityriasis rubra pilaris, drug eruption, and cutaneous T-cell lymphoma) must be excluded.
Treatment
Therapy includes topical medications, UV-based treatment, and systemic drugs. For mild disease, topical therapy such as with topical corticosteroids (e.g., triamcinolone ointment, 0.1% twice daily for 1 to 2 weeks), anthralin, calcipotriene cream (0.005%, twice daily as needed), tazarotene (0.05% gel, once or twice daily as needed) or with tar preparations (crude coal tar, 2% daily for 2 weeks), used alone or in combination, is effective. In patients who have widespread lesions, NB-UVB is the best option, whereas PUVA should be considered for patients in whom NB-UVB therapy has failed. For patients with recalcitrant disease, oral medications such as methotrexate (7.5 to 15 mg/week), acitretin (25 to 50 mg/day), cyclosporine (3 to 5 mg/kg/day), hydroxyurea (1 g/day), and mycophenolate mofetil (1 to 2 g/day) have all been used with success.
The most recent advance in the treatment of psoriasis is the use of the biologic agents, which are most appropriately used in patients who have widespread disease and in whom UV-based therapy or treatment with one of the systemic medications has failed (Table 464-4). Tumor necrosis factor-α (TNF-α) inhibitors include the following: etanercept, a human TNF-receptor/immunoglobulin G1 fusion protein; infliximab, a chimeric mouse anti–TNF-α antibody; and adalimumab, a human immunoglobulin G1 anti–TNF-α antibody. A CD2 antagonist is alefacept, a protein that is fused to IgG and that contains the binding site of lymphocyte function–associated antigen-3, which binds to CD2 markers on the surface of memory T cells. An anti-CD11a is efalizumab, a humanized monoclonal antibody.
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Pityriasis Rubra Pilaris
Epidemiology
Pityriasis rubra pilaris occurs equally in men and women; the incidence ranges from 1 in 5000 new dermatology patients in Great Britain to 1 in 50,000 in India. This disease most frequently occurs as the acquired form, although a familial form (autosomal dominant with variable expression) also occurs. Sixty percent of patients have adult-onset disease, with peak incidences in the first, second, and fifth to sixth decades. Abnormal vitamin A metabolism has been postulated as a possible cause.
Clinical Manifestations
Clinically, patients present with erythematous to orange papules and plaques on all parts of the body (Fig. 464-10). Characteristically, skin appears normal between these lesions (“islands of sparing”). Erythema, hyperkeratosis, and fissures of the palms and soles are common; when severe, these lesions result in functional impairment. Many patients have follicular keratotic papules on the dorsa of the fingers and occasionally on the elbows as well as on the wrists. The nails are yellow and thickened, with distal splinter hemorrhages. In adult patients, the condition typically starts on the face and moves to the lower extremities; in the juvenile form, it usually starts in the lower half of the body. Ectropion may occur, and pruritus is observed in approximately 20% of patients. In contrast to psoriasis, arthritis is uncommon. Pityriasis rubra pilaris has been associated with HIV infection (Chapter 415).
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| FIGURE 464-10 Pityriasis rubra pilaris. Note the erythematous orange plaques with islands of sparing. |
Diagnosis
Definitive diagnosis can usually be made based on the clinical presentations and by the characteristic histologic findings of alternating vertical and horizontal parakeratosis in the stratum corneum.
Treatment
The most effective treatment is with oral retinoids (acitretin, 25 to 50 mg/day for 1 to 2 months). Methotrexate (7.5 to 15 mg/week), either as a monotherapy or in combination with oral acitretin (25 to 50 mg/day), is also beneficial. Other options include PUVA (8-methoxypsoralen, 0.4 to 0.6 mg/kg, with gradually increasing doses of UVA, three times weekly for 8 to 10 weeks), or cyclosporine (3 to 5 mg/kg/day). For all patients, topical over-the-counter emollients should be used as needed, and topical keratolytic agents, such as ammonium lactate lotion 12%, twice daily as needed, are helpful as adjunctive therapy.
Pityriasis Rosea
Epidemiology and Pathobiology
The incidence of pityriasis rosea has been reported as 3 to 30 per 1000 patients. It occurs in all ethnic groups, most commonly in the third and fourth decades of life, with a slight female predominance. The cause is not known, and a possible association with human herpesviruses 6 and 7 has been reported.
Clinical Manifestations
In 50 to 90% of patients, pityriasis rosea starts with a primary lesion (herald patch), which is an erythematous, scaly, oval patch a few centimeters in diameter. This lesion is usually followed within a few days by smaller erythematous scaly patches on the trunk, less commonly on the proximal extremities (Fig. 464-11). As a rule, the palms and soles are spared. The distribution of the eruption, especially on the back, tends to follow the lines of cleavage of the skin, with a resulting “Christmas tree” distribution. Lesions are most commonly asymptomatic, although they may be mildly pruritic. The eruption is self-limiting and resolves within 6 to 8 weeks. In rare instances, lesions may persist.
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| FIGURE 464-11 Large erythematous oval patch (herald patch) of pityriasis rosea accompanied by smaller erythematous patches. |
Diagnosis
The diagnosis can usually be made clinically. The most important differential diagnosis is secondary syphilis, which, in contrast to pityriasis rosea, usually involves the palms and soles. In many instances, a rapid plasma reagin test is advisable to exclude syphilis.
Treatment
Treatment is primarily symptomatic, including topical corticosteroids and oral antihistamines. NB-UVB phototherapy or PUVA should be reserved for patients with severe, recalcitrant cases.
▪Lichen Planus
Epidemiology
Lichen planus occurs most commonly in patients between 30 and 60 years of age. Women are affected more frequently than men and tend to be somewhat older at the onset of disease. The prevalence in the general population is about 1%.
Pathobiology
Histologically, lichen planus is characterized by dense lymphocytic infiltrate at the dermal-epidermal junction. The infiltrates consist of predominantly T cells, a finding suggesting the pathogenic role of cell-mediated immunity. Because lichen planus or lichen planus–like eruptions can occur after exposure to drugs or chemicals (e.g., color film developer), the role of drugs and chemicals in inducing a T-cell–mediated response against the epidermis has been postulated. Lichen planus may be associated with hepatitis C infection (Chapter 152).
Clinical Manifestations
Clinically, patients usually present with erythematous to violaceous flat-topped papules, often with white lacy lines (Wickham's striae) on the wrists, forearms, and genitalia (Fig. 464-12). Oral lichen planus occurs as white papules and plaques with a reticulated appearance, most commonly along the bite line on the buccal mucosa. Occasionally, erosion may occur. Hypertrophic lichen planus usually occurs on the lower extremities as lichenified, violaceous plaques, probably secondary to chronic rubbing and scratching of the lichen planus lesions. Erosive lichen planus occurs as erosion usually surrounded by violaceous discoloration at the periphery; this variant tends to occur more commonly on the feet. Bullous lichen planus occurs as vesicles or bullae arising from a preexisting lesion of lichen planus. Lichen planopilaris occurs as violaceous papules and plaques involving the scalp, most prominently surrounding the hair follicles; it progresses to scarring alopecia. Lichen planus actinicus, a variant of lichen planus occurring most commonly in the Middle East, tends to occur on the sun-exposed areas such as the forehead; it occurs as papules or plaques with minimally elevated rolled edges. Atrophic lichen planus resembles typical lichen planus lesion but with a central area of superficial atrophy. Lichen planus of the nails occurs as thinning of the nail with longitudinal ridges; it may progress to complete loss of the nail plate (pterygium formation).
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| FIGURE 464-12 Erythematous papules on the wrist of a patient with lichen planus. |
Diagnosis
The diagnosis can be made by clinical appearance. It is confirmed by the characteristic histologic findings of infiltration by lymphocytes at the dermal-epidermal junction.
Treatment
Several treatment options are available. Topical corticosteroids (e.g., triamcinolone ointment, 0.1% twice daily for 1 to 2 weeks) are helpful in patients with limited disease. Hypertrophic lichen planus can be treated with topical corticosteroids (fluocinonide 0.05% ointment twice daily for 2 to 3 weeks), with occlusion at night, or with interlesional corticosteroid injections (triamcinolone suspension, 3 to 5 mg/mL). A 6- to 8-week course of oral corticosteroid is helpful in patients with widespread lichen planus. NB-UVB phototherapy or PUVA is helpful for widespread conditions. Oral acitretin (25 to 50 mg/day) or systemic cyclosporine (3 to 5 mg/kg/day) has been used with good success in some patients. Oral lesions can be treated with topical corticosteroids (triamcinolone 0.1% paste, twice daily for 2 to 3 weeks), topical retinoids (tretinoin gel 0.01% twice daily for 3 to 4 weeks), or cyclosporine solution (100 mg/mL, 1 mL, twice daily, swish and swallow). Without treatment, cutaneous lesions resolve in approximately 1 year, whereas oral and hypertrophic lesions tend to be much more chronic, persisting for 4.5 years and 8.5 years, respectively.
▪Lichen Nitidus
Lichen nitidus is a rather uncommon condition that usually occurs in children or young adults. The incidence has been estimated to be 3.4 cases per 10,000 population. It is more commonly observed in dark-skinned individuals. The cause is unclear, and no infectious agent has been identified.
The lesions are 1- to 2-mm, shiny, skin-colored discrete papules, sometimes with fine scales on their surface, occurring most commonly on the genitalia or forearms and occasionally on the trunk. A generalized form has rarely been reported. Lesions are usually asymptomatic. Histologically, one sees a dense lymphocytic infiltrate in the superficial dermis and at the dermal epidermal junction. In contrast to lichen planus, in which the infiltrate tends to involve the entire section of the skin, the infiltrate in lichen nitidus tends to be much more focal and localized.
The diagnosis usually can be confirmed from the typical clinical appearance and the characteristic histologic changes. The condition tends to remit spontaneously in a few years, so therapy, with topical corticosteroids (e.g., triamcinolone ointment, 0.1% twice daily for 2 weeks) and oral antihistamines (e.g., fexofenadine, 180 mg every morning, and hydroxyzine, 25 to 50 mg at bedtime, as needed) should be reserved for symptomatic cases only.
▪Secondary Syphilis
Lesions of secondary syphilis typically occur 1 to 2 months after the development of a primary chancre lesion (Chapter 340). However, up to 25% of patients may not remember having a chancre. Once the eruption occurs, it lasts for 1 to 3 months.
Clinically, secondary syphilis may appear as erythematous macules (“roseola syphilitica”), erythematous to hyperpigmented oval or circular papules and plaques covered with scales, or a maculopapular eruption. Nodular eruption may also occur occasionally. The lesions tend to be widespread, and the palms and soles are very frequently involved (Fig. 464-13). The diagnosis is made based on the history, physical examination, and a positive rapid plasma reagin test. Skin biopsy shows the proliferation of endothelial cells in the dermis and a dense dermal infiltrate containing many plasma cells. Intramuscular penicillin is the treatment of choice.
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| FIGURE 464-13 Scaly papules and plaques on the palm of a patient with secondary syphilis. |
▪Pityriasis Lichenoides
Pityriasis lichenoides occurs as erythematous papules that may be minimally pruritic and covered with scales, scattered on all parts of the body. In the acute form (pityriasis lichenoides et varioliformis acuta [PLEVA]), the central part of the lesions develops vesicles, pustules, and hemorrhages, with eventual crusting of the lesions. The patient may have mild constitutional symptoms of fever and malaise. The chronic form (pityriasis lichenoides chronica [PLC]) occurs as asymptomatic erythematous to hyperpigmented papules and plaques covered with fine scales; the trunk and extremities are common sites. Histologically, both PLEVA and PLC are characterized by dense lymphocytic infiltrates in the dermis, with CD8 lymphocytes predominating in PLEVA and CD4 lymphocytes in PLC.
PLEVA usually resolves in a few months, although it can persist. PLC usually lasts for a few years. PLEVA is less common than PLC, although both disorders affect patients of all ages, with a slight male predominance.
Treatment generally follows a sequential order: (1) topical corticosteroids (e.g., triamcinolone ointment, 0.1% twice daily for 1 to 2 weeks) and antihistamines, (2) tetracycline (1 to 2 g/day), or erythromycin (1 to 2 g/day), (3) NB-UVB phototherapy (three times weekly for 8 to 10 weeks with increasing doses of NB-UVB) or PUVA, and (4) methotrexate (7.5 to 15 mg/week).
▪Parapsoriasis
The two common variants of parapsoriasis are large plaque parapsoriasis and small plaque parapsoriasis. The peak incidence is in the fifth decade, although rare cases may begin in childhood. Large plaque parapsoriasis appears as oval to circular, erythematous to hyperpigmented macules and patches with fine scales and superficial atrophy (crinkling atrophy) scattered on all parts of the body (Fig. 464-14). These lesions are usually larger than 5 cm. Although lesions may be minimally pruritic, they are usually asymptomatic. Large plaque parapsoriasis is considered by some to be a less aggressive variant of mycosis fungoides (see later). Small plaque parapsoriasis appears as circular to oval erythematous to hyperpigmented patches or minimally elevated plaques, with lesions less than 5 cm in diameter and usually covered with fine scales. Digitate dermatosis is a distinct variant of small plaque parapsoriasis in which lesions appear along the line of cleavage, usually on the lateral aspect of the trunk in the shape of fingerprints. Histologically, large plaque parapsoriasis is characterized by a dermal lymphocytic infiltrate, which may extend into the epidermis, whereas small plaque parapsoriasis is characterized by spongiotic dermatitis, with a mild superficial lymphocytic infiltrate in the dermis. In up to one third of patients, large plaque parapsoriasis may evolve into mycosis fungoides. As a result, treatment of large plaque parapsoriasis is similar to that of early-stage mycosis fungoides: high-potency topical corticosteroids, topical nitrogen mustard, NB-UVB phototherapy, and PUVA. By comparison, patients with small plaque parapsoriasis have a benign course, and management of small plaque parapsoriasis should be symptomatic only, with emollients, topical corticosteroids, and NB-UVB phototherapy.
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| FIGURE 464-14 Erythematous patches with fine scales in a patient with large plaque parapsoriasis. |
▪Mycosis Fungoides
Mycosis fungoides is a variant of cutaneous T-cell lymphoma (Chapter 196). The four types of cutaneous manifestations are patch, plaque, tumor, and erythrodermic. The patch stage of mycosis fungoides manifests as patches with fine “cigarette paper” wrinkling of the epidermis. The patches can be skin colored or minimally erythematous; hyperpigmented or hypopigmented lesions are frequently seen in dark-skinned patients. The patches can vary from a few millimeters to a few centimeters in diameter; they are more common on sun-protected areas such as the buttocks (Fig. 464-15). The patches are usually asymptomatic, although they occasionally may be mildly pruritic. Lesions may be present for years. As the disease progresses, some of the patches may become more indurated and may evolve into more elevated plaques. Nodular lesions may occur in patients without any patch or plaque lesions, although more commonly these lesions occur in conjunction with patches and plaques. Erythrodermic mycosis fungoides occurs as a generalized erythroderma with significant scaling and pruritus. Hyperkeratosis of the palms and soles, as well as fissuring of hands and feet, are quite common. In dark-skinned patients, mycosis fungoides may appear as hypopigmented patches.
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| FIGURE 464-15 Hyperpigmented patches in a patient with mycosis fungoides. |
The diagnosis is confirmed by histologic demonstration of atypical mononuclear cells both in the epidermis and in the dermis, as well as immunophenotypic markers showing predominance of CD4 cells in the infiltrate. Therapy for mycosis fungoides generally follows a sequential order: (1) topical nitrogen mustard (i.e., mechlorethamine, 10 mg in 60 mL of water, applied daily until lesions resolve, then taper), or NB-UVB, each of which can be combined with topical corticosteroids (e.g., triamcinolone ointment, 0.1% twice daily for 1 to 2 months); (2) PUVA; (3) topical retinoids (e.g., bexarotene gel, 1% once to four times daily, until lesions resolve); and (4) one of the following: oral bexarotene (300 mg/m2/day for 2 to 4 months) or interferon-α (3 to 9 million U subcutaneously 3 times weekly for 2 to 4 months). Erythrodermic disease is most effectively treated with extracorporeal photopheresis.
▪Dermatophytoses
Fungal infections that occur as papulosquamous eruptions include tinea corporis, tinea manuum, tinea cruris, and tinea pedis. Tinea corporis causes a polycyclic erythematous scaly patch that has elevated borders and consists of papules and sometimes pustules. As the lesion progresses, the border advances centrifugally. The trunk is the most common site. Tinea cruris has similar morphologic features, except it is located in the inguinal folds and expands centrifugally from the folds. In men, the scrotum is usually spared. Tinea manuum presents as an erythematous scaly patch with an advancing active border, usually located on the dorsum of the hands, or it may occur as diffuse scaly patches with mild hyperkeratosis involving part or the entire surface of the palm and palmar aspect of the fingers. Tinea pedis also has two clinical manifestations: it can occur as scaly macerated lesions with erythema in the toe webs or as patchy or diffuse scaliness on the sole extending to the medial and lateral aspect of the foot (moccasin distribution). The latter presentation can be associated with diffuse scaliness of one but not both palms, a condition known as the “one-hand, two-feet syndrome.” The diagnosis can be confirmed by examination of skin scrapings using 10% potassium hydroxide preparation and/or by fungal culture. Treatment consists of topical or oral antifungal medications (e.g., clotrimazole cream, 1%, twice daily for 2 to 4 weeks, or terbinafine, 250 mg for 2 to 12 weeks, depending on the site involved).
▪ Tinea Versicolor
Tinea versicolor is a fungal infection of the skin caused by Malassezia furfur. It occurs in otherwise healthy young individuals, especially in warm and moist environments during the summer. Clinically, it appears as macules and patches with very fine scales; the color can be hypopigmented, skin colored, minimally erythematous, or light brown (Fig. 464-16). The patches start as perifollicular macules, with the midchest and midback the most common sites. As the lesions progress, hypopigmentation of the skin may also occur. The lesion usually is asymptomatic. The diagnosis is confirmed by the characteristic appearance of the fungal elements on a 10% potassium hydroxide preparation: grapelike clusters of yeast and short, septate branching hyphae (“spaghetti and meatballs” appearance). Treatment is with 2.5% selenium sulfide shampoo (applied for 10 minutes then wash off, 5 times weekly for 4 to 6 weeks), topical antifungal preparations (e.g., clotrimazole cream, 1% twice daily for 4 weeks), or a 1- to 3-day course of oral ketoconazole (200 mg/day) or itraconazole (200 mg/day).
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| FIGURE 464-16 Hypopigmented patches of tinea versicolor. |
▪FIGURATE ERYTHEMAS
These conditions appear as erythematous circular or polycyclic plaques with central clearing and, frequently, centrifugally migrating border (Table 464-5). Occasionally, fine scaling may also be observed. The extremities are the most common sites. The diagnosis can frequently be made by the typical history and morphologic features.
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Erythema annulare centrifugum is most commonly idiopathic; however, it can also be a manifestation of a hypersensitivity response to medications. Management includes identification of a precipitating agent (if possible) and treatment with topical or systemic corticosteroids. Erythema gyratum repens occurs as concentric erythematous plaques with fine scales, resembling a “wood-grain” pattern. This unusual form of figurate erythema has been associated with malignant hematologic diseases and with carcinomas of the breast, lung, gastrointestinal tract, prostate, and cervix. Treatment of the underlying malignant disease results in the resolution of the skin lesion in a few months. Erythema chronicum migrans, which is a cutaneous manifestation of Lyme disease and is caused by the spirochete Borrelia burgdorferi (Chapter 342), appears as a concentric ring of erythema that progresses centrifugally from the site of a tick bite. Occasionally, it may appear as a circular erythematous patch. The diagnosis is made by a history of a tick bite, the characteristic cutaneous lesion, and/or elevated serum antibodies to B. burgdorferi. Management is the same as for Lyme disease.
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