White : Diseases of the Skin - Pediatric Dermatology

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Gary M. White & Neil H. Cox

Diseases of the Skin

19	Pediatric Dermatology

MISCELLANEOUS

Juvenile xanthogranuloma

The juvenile xanthogranuloma (JXG) is a relatively common growth on the skin of a child. Most are either congenital or arise in the first year of life, although adults may be affected. A yellowish red papulonodule in a newborn or young child is characteristic (Figs 19.78 and 19.79). Micronodular or macronodular (giant) forms (Fig.19.80) occur. The cutaneous lesions may be multiple and, rarely, are associated with systemic disease. Ocular hemorrhage, glaucoma, pulmonary effusion, testicular swelling, central nervous system involvement, and hepatosplenomegaly have all been reported. Death may rarely occur. The triad of JXGs, neurofibromatosis, and myelogenous leukemia has been reported (see under earlier heading Neurofibromatosis).

The yellowish color is usually characteristic, but the differential diagnosis of a solitary nodule in an infant may include the following.

•	Solitary mastocytoma.
•	Fibrous hamartoma of infancy.
•	Tumor—for example rhabdomyosarcoma.
•	Infantile myofibromatosis.
•	Langerhans cell histiocytosis.

No treatment is usually needed, as spontaneous resolution usually takes place over months to years. Any patient with ocular symptoms or multiple lesions should undergo an ophthalmologic examination. Intralesional triamcinolone has been used.

Figure 19.76 Thick, hyperkeratotic skin. Tremendous hyperkeratosis may occur. The woman pictured here donned four pairs of stockings before going to work.

Figure 19.77 Epidermolytic hyperkeratosis. (a) Areas of thick, verrucous hyperkeratosis surrounding islands of normal skin. (b) The cause of the islands of normal skin is erosions that result from shedding of the thick, hyperkeratotic layer.

Figure 19.78 Juvenile xanthogranuloma (see also Fig. 8.90). Note the characteristic orange color of this papule in a child.

Figure 19.79 Juvenile xanthogranuloma (JXG). (a,b) This young boy had multiple JXG and neuro?bromatosis.

Figure 19.80 Giant juvenile xanthogranuloma. (Courtesy of O. Dale Collins III, M.D., Ph.D.)

Figure 19.81 This benign adnexal tumor is a common cause of a dermal or subcutaneous papulonodule on the face of a child.

Pilomatricoma

The pilomatricoma is a common tumor on the face of children (Fig.19.81). See Chapter 23 for a complete discussion.

Juvenile plantar dermatosis

Juvenile plantar dermatosis (JPD) is a dermatitis of the balls of the feet that affects young children. Some have hypothesized that it is caused by the constant cycle of wet feet drying. Shiny, cracked, erythematous areas, most prominent over the toes and ball of the foot, are characteristic (Fig.19.82). It occurs typically in prepubertal children during the winter and may be associated with atopic dermatitis. Tinea pedis and shoe dermatitis should be excluded, especially in older children (most idiopathic cases are in children aged 5–10 years). Fingers may also be affected in about 10% of patients.Many patients get benefit from applying a low- to medium-potency steroid ointment immediately after removing the shoes. This locks in the moisture and prevents the constant wet to dry cycle.

Keratosis pilaris

Etiology and pathogenesis

Keratosis pilaris (KP) is caused by the formation of an orthokeratotic plug that blocks and dilates the orifice and upper portion of the follicular infundibulum. One study found KP to be associated with high body mass index, leg skin dryness, and atopy. In one study, the onset was in the first decade in 51% of cases, the second in 35%, the third in 12%, and the fourth in 2%. (Some have reported a postpregnancy flare.) KP is usually better in the summer and worse in the winter.

Figure 19.82 Juvenile plantar dermatosis.

Clinical

Clinically, there are tiny (1mm), follicular, hyperkeratotic papules, with or without erythema, on the upper, outer arms (Fig.19.83). The anterior thighs, buttocks, and cheeks may also be affected, and a diffuse truncal eruption may rarely occur. Tiny follicular pustules may be seen.

Differential diagnosis

Keratosis pilaris is usually easily recognized, but more inflammatory cases may be confused with eczema or folliculitis.

Treatment

No treatment is consistently effective. Daily use of an abrasive pad may smooth the skin somewhat. A medium-potency topical steroid for the erythema, 20% urea cream once to twice daily, lactic acid (12% twice a day), or tretinoin (0.1% cream every day) are alternatives. Other anecdotal reports of improvement include those due to sun, 30% glycolic acid in an ointment base, or tetracycline. Calcipotriene has been reported as ineffective. One report has recommended, for very motivated patients, monthly light chemical peels using 15–20% trichloroacetic acid (TCA) for several months followed by 20% glycolic acid compounded in a cream or lotion (e.g. Shepherd's lotion).

Keratosis rubra pilaris

A term used when the redness of KP is marked. Sometimes, there is just follicular erythema without plugging. Sometimes the term keratosis pilaris atrophicans is used. Both the tunable dye laser and the potassium titanyl phosphate laser have been used successfully to treat the erythema.

Keratosis pilaris atrophicans

Scarring, inflammatory KP of the face, extremities, and trunk, with some patients having scarring alopecia of the scalp, is characteristic of keratosis pilaris atrophicans (KPA). Variable erythema and follicular papules may be seen in the eyebrows, cheeks, extensor aspects of the extremities, and trunk (Fig.19.84). Partial alopecia may occur, especially prominent in the eyebrows. This general category encompasses ulerythema ophryogenes, atrophoderma vermiculatum, and keratosis follicularis spinulosa decalvans.

Keratolytics, such as salicylic acid gel or ammonium lactate lotion, may give the skin a smoother feel. Topical steroid lotions or creams should also be tried and may help some. Tretinoin and isotretinoin helped little in one study.

Proteus syndrome

A congenital, lobulated, cerebriform mass on the sole of the foot is characteristic of the Proteus syndrome (Fig.19.85) and was found in 83% in a recent study of 24 patients. Other features include hemihypertrophy, macrodactyly, macrocephaly and other skull abnormalities, mesodermal hamartomas (e.g. lipoma [90%], fibroma, and lymphatic and capillary vascular malformations), exostoses, epidermal nevi (67%), patchy dermal hypoplasia, and scoliosis. The patchy dermal hypoplasia is characterized by a large area of slight dermal hypoplasia with an irregular outline. A sharp midline demarcation or prominent venous vasculature may be noted. Despite the fact that skull abnormalities are common, mental retardation is rare.

Figure 19.83 Keratosis pilaris: (a) tiny follicular keratotic papules on the outer arm of a child—the most common location; (b) perifollicular erythema.

Figure 19.84 Keratosis pilaris atrophicans (KPA): (a) KPA of the eyebrows; (b) KPA of the cheeks. This erythematous appearance of the cheeks is frequent, the individual keratosis pilaris lesions usually being most apparent at the margins. The erythema is very refractory to treatment, but topical retinoids may improve the follicular keratosis. Sparse lateral eyebrows are also apparent in this case, a variant known as ulerythema ophryogenes.

The cerebriform collagenoma may also occur as an isolated plantar or palmar lesion.

Subepidermal calcified nodule

The subepidermal calcified nodule (SCN) is made up of calcium deposited just below the skin. It has been theorized that this represents dystrophic calcification after dermal injury. Many have a warty architecture and thus may have originally been verrucas. A solitary congenital papulonodule of the ear, often with crusting, is characteristic (Fig.19.86). Alternatively, the SCN may occur on the face, finger, knee, or palm. The surface may be hyperkeratotic or verrucous, and there may be multiple lesions. One case was associated histologically with a hair follicle nevus. No treatment is needed, but simple shave excision may be done.

Langerhans cell histiocytosis

Etiology and pathogenesis

Langerhans cell histiocytosis (LCH), formerly histiocytosis X, represents a proliferation of Langerhans cells in the skin. In the past, LCH has been separated into Letterer–Siwe disease (infants, aggressive, internal involvement), Hand–Schüller–Christian disease (children; bony defects, especially of the skull; diabetes insipidus; and exophthalmos), and eosinophilic granuloma (children and adults, granulomas of the skin and bones, benign, chronic). (Other histiocytoses are discussed in Ch.11.) Human herpesvirus 6 has been found in a significant number of cases and may be etiologically significant.

Clinical

Langerhans cell histiocytosis in an infant may present as a red, scaly, seborrheic dermatitis-like rash of the scalp (Fig.19.87). It has been often said that LCH resembles seborrheic dermatitis, but this is not very accurate, as the eruption usually consists of discrete papules. Dermatophytes may coexist. Other cutaneous presentations include a persistent intertrigo of the groin, otitis externa along with otitis media, yellowish brown xanthomatous lesions, petechiae, erythematous papules, eczematous areas, or vesicopustular lesions. The oral mucosa may be involved, with gingival or dental lesions. Nail involvement may occur.

Figure 19.85 An isolated cerebriform collagenoma often seen in Proteus syndrome.

Figure 19.86 Subepidermal calci?ed nodule on the upper eyelid.

Langerhans cell histiocytosis seems to represent a clonal proliferation of Langerhans cells. Immunohistochemistry stains the histiocytes with S100 and CD1a. Electron microscopy shows a significant number of the cells to contain Birbeck granules, which resemble racquets. Tzanck preparation can be diagnostic, showing multiple histocytic cells with reniform nuclei.

History and physical examination (including ear examination to exclude otitis and abdominal examination to exclude hepatosplenomegaly), skin biopsy, complete blood count, liver function tests, creatinine, skeletal survey (e.g. of the skull, long bones, and thorax), bone marrow biopsy, CT scan of the body, and MRI of the hypothalamic region may be performed.

Differential diagnosis

This depends on the clinical subtype, age group, and morphology in the individual patient. In children, the main differential diagnoses are the various causes of napkin rash (Table 19.1) or intertrigo, seborrheic dermatitis, otitis externa, and skin infections.

Treatment

The evaluation and treatment of the patient should involve a specialist in the field. The condition often resolves spontaneously in 1–3 months (previously termed congenital self-healing histiocytosis). Thus a period of initial observation is appropriate in mild to moderate cases. For aggressive disease, therapies that have been used include prednisone, radiation therapy, chemotherapy, and nitrogen mustard. Etoposide, a semisynthetic derivative of podophyllotoxin, has been effective in both children and adults. Thalidomide (100mg/day followed by 50mg/day) has been used effectively in adults.

Spontaneous resolution of skin lesions may be followed by relapse (e.g. bony lesion at 6 months of age, diabetes insipidus at 4 years of age, cutaneous relapse at 3 months, and scalp nodule at 3 years). Therefore long-term follow-up is recommended.

Infantile acropustulosis

Recurrent crops of pruritic pustules on the palms and soles of a child, usually less than 2 months to 10 years of age, is characteristic (Fig.19.88). Bacterial culture and scabies preparations should be done. The relationship to scabies remains unclear. Some cases may represent a hypersensitivity to the mite, while others seem unrelated. The clinical situation is confused
by the fact that many patients are treated empirically with antiscabetic preparations. Thus a hypersensitivity reaction to persistent mite antigen(s) is difficult to exclude completely in some patients.

Figure 19.87 Langerhans cell histiocytosis (formerly called histiocytosis X) in an infant may present as a red, scaly, seborrheic dermatitis–like rash of the scalp. (Courtesy of Michael O. Murphy, M.D.)

Betamethasone dipropionate applied and occluded for 1–2 days has been recommended. Dapsone is an oral medication that has been used successfully. However, its significant side effect profile limits its usefulness in infants and young children.

PRACTICE POINTS

•	Scabies must be carefully excluded before the diagnosis of infantile acropustulosis is made.

Infantile digital fibromatosis

Solitary or multiple nodules slowly enlarging and limited to an infant's fingers or toes are characteristic of this rare disease. The thumb and great toe are not involved. Onset is typically in the first years of life, often in the first month. Approximately one-third of cases are congenital. The lesions may recur but never metastasize. Histologically, one sees characteristic small, round, eosinophilic inclusion bodies in the cytoplasm of some of the fibroblasts. Deviation deformities and contractures may develop in the absence of surgery.

Biopsy is usually needed to confirm the diagnosis. Observation is appropriate, as these lesions resolve over several years. Surgery may be performed to correct any functional problems.

Pseudoainhum

Circumferential constriction of a digit (finger or toe) may occur in a variety of disorders, including many of the keratodermas, leprosy, erythropoietic protoporphyria, Olmsted syndrome, and porokeratosis of Mibelli, and from strangulation by hair or string (Fig.19.89). True ainhum describes the progressive amputation of the fifth toe that occurs in certain African countries.

Child abuse

Acute skin changes that are asymmetric, or have unusual shapes suggesting an external cause, should prompt the consideration of abuse. Scalding burns or unusual bruising are typical (Fig. 19.90).

Figure 19.88 (a,b) Infantile acropustulosis. Recurrent crops of pruritic pustules on the palms and soles of an infant or young child are characteristic.

Figure 19.89 Pseudoainhum secondary to a hair in a young child. (Courtesy of O. Dale Collins III, M.D., Ph.D.)

Figure 19.90 Child abuse. (a) Purpuric lesions with a shape suggestive of an external cause. (b) Acute bullous lesions in a child should prompt consideration of a burn. (Panel a courtesy of O. Dale Collins III, M.D., Ph.D.) .

Recurrent palmoplantar hidradenitis in children

Recurrent episodes of tender, erythematous, inflammatory nodules on the soles and/or palms are characteristic. Involvement of both soles or only one sole may occur. Low-grade fever may be associated. Individual episodes usually resolve within 12 days. Histologically, one sees a neutrophilic infiltrate surrounding the eccrine apparatus, particularly the coils. It is theorized that obstruction of the sweat duct and subsequent inflammation and/or rupture causes this disease. Several patients have been noted to have performed heavy physical activity before the onset. In two children, use of cotton tights with a Gore-Tex membrane while wearing boots during cold weather was associated; stopping use of the cotton tights cured the patients.Treatment is conservative and symptomatic, as the condition is self-limited.