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PUPPURA

Classification

Tiny lesions of purpura are termed petechiae (lesions of up to a few millimeters), while large areas are termed ecchymosis (bruise). Causes overlap, but the pattern can be clinically useful; for example, abnormalities of clotting factors are most likely to cause bruising, whereas platelet defects often cause petechiae. A classification of purpura with examples of specific causes is provided in Table 14.1.

Capillary leakage

Bruises and purpura

This chapter is primarily a discussion of inflammatory disorders that affect blood vessels and that are likely to present to dermatologists or internists. However, extravasation of blood may occur in other settings (Table 14.1), including the following.

    Knowledge of colors in a bruise may be important, particularly in instances of suspected child abuse. Red color may be present at any age of bruise, although it usually disappears by the end of the first week (Fig. 14.3). Yellow color takes at least 24 h to appear and green 48 h, these colors therefore indicating that the bruise is not fresh (delayed presentation is one feature of abuse).

Figure 14.2 Purpura on the eyelids. This child had an upper respiratory illness 2 weeks previously, with severe coughing. This pattern of purpura is essentially the result of increased pressure due to the Valsalva maneuver, and mainly affects the poorly supported, thin skin of the eyelids. This process also occurs in systemic amyloidosis.

Figure 14.3 An ecchymosis (bruise), showing mixed colors about 24 h after the injury.

Talon noir

This disorder is specifically discussed due to the diagnostic confusion it may cause. The lesions are multiple small, hemorrhagic, and thrombosed capillaries, which typically occur on the border of the heel in teenaged and young adult sportsmen due to shearing injury (Fig.14.4). Similar lesions may occur on the sole of the foot over areas of irregularity in the soles of shoes, or on the hands if there is a frictional injury.

    The lesions may be black and confused with melanoma, but close examination reveals the typical discrete, small spots of the damaged vessels. Some are diagnosed as warts. Less commonly, if they occur at sites on the foot other than the typical distribution on the heel, the differential diagnosis may include some forms of vascular occlusion, such as cholesterol emboli.

    No treatment is required. The punctuate hemorrhages are gradually shed as the plantar epidermal turnover occurs.

Figure 14.4 Talon noir. (a) Shear forces in this soccer player caused extravasation of blood at the lateral margins of the heel. (b) A similar change may occur on the hand.

Capillaritis (capillaropathy)

This term is applied to a group of disorders that share the common feature of erythrocyte extravasation and mild inflammatory changes around capillaries, sometimes with endothelial cell swelling but without frank vasculitis. In some cases, capillaritis occurs as a generalized self-limiting tendency following a viral infection or may be drug-triggered; some cases on the lower leg are clearly related to varicose veins.

    Most types of capillaritis are idiopathic; the commonest variants occur mainly in children and young adults, and are often limited to the legs. A variety of eponymous names are applied, the commonest patterns being considered to be variants of disorders described by Majocchi or Schamberg. The main patterns are localized versions (with either prominent purpura or with predominantly golden-brown staining) and a generalized version (Figs 14.5 – 14.9).

Figure 14.5 Lichen aureus, all lesions on the leg in different patients. This pattern of golden-brown lesion is most frequent in children, and is usually asymptomatic or mildly itchy when it first appears. (a) Typical morphology and site; (b) the golden-brown color of an older lesion; (c) a close-up view of early lichen aureus, demonstrating fresh pinpoint spots of capillary leakage, with a ‘cayenne pepper’ pattern.

Figure 14.6 Purpura annularis telangiectoides (Majocchi disease) demonstrating annular and arciform lesions with a prominent purpuric component, on the leg of an otherwise well child.

Figure 14.7 A more inflammatory and widespread capillaritis, in which there would be suspicion of true vasculitis features.

Figure 14.8 Capillaropathy on the neck of a child. He also had accentuation of lesions at sites of pressure from clothing and from a car seat belt. This presumably had a viral trigger, as the lesions faded over a few weeks.

Figure 14.9 Older lesions of capillaropathy (Schamberg type) may look darker, probably because of some stimulation of overlying melanocytes, as occurs in venous stasis disease.

Lichen aureus

This is probably the most common idiopathic capillaropathy, usually occurring in children. Lesions, which are generally solitary or few in number, are usually fairly well but not sharply circumscribed, and consist of multiple tiny red (‘cayenne pepper') spots that gradually turn yellowish orange as iron pigment is deposited by breakdown of erythrocytes in the tissues (Fig.14.5).

Schamberg disease

This also occurs in children, or in young adults. There are generally multiple lesions, mainly on the legs but sometimes extensive (Fig.14.9). They have the purpuric component described for lichen aureus, but this is generally less intense and the overall color of the lesions is brownish. There may be mild irritation of the skin and overlying fine scaling.

Purpura annularis telangiectatica (Majocchi disease)

This is a more florid disorder, in which the lesions are more overtly purpuric and usually arciform or annular, and hence may be confused with a vasculitis (Fig.14.6). There is some overlap with the features of lichen aureus in older lesions.

Generalized capillaropathy

This can occur as a transient phenomenon, often lasting a few weeks then gradually fading (Figs 14.7 and 14.8). This sequence suggests that it may just be a type of viral exanthem, but no specific cause is usually identified, and systemic involvement is not clinically apparent.

Differential diagnosis

The lesions of Schamberg disease can be confused with eczema, particularly of discoid type, although the latter is much more pruritic. Vasculitis may need to be excluded. In younger children especially, the purpuric bruise-like appearance of some lesions may raise concerns about abuse.

Treatment

No treatment is very useful. Topical corticosteroids may be used if itch is a feature. Support stockings are felt to be useful if the lesions are particularly on the lower legs, and especially if there is any evidence of venous disease.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.