Chapter 168. Pigmented Purpuric Dermatoses

The pigmented purpuric eruptions are a group of dermatoses characterized by petechiae, pigmentation, and, occasionally, telangiectasia in the absence of associated venous insufficiency or hematologic disorders (Table 168-1). Synonyms include persistent pigmented purpuric dermatitis, purpura simplex, and purpura pigmentosa chronica. They are found most commonly on the lower extremities; however, the lesions may involve the upper body and rarely become generalized. There are reports of palm, sole, genital, and oral mucosal involvement. These benign, generally asymptomatic eruptions tend to be chronic, with remissions and flares. They share common histopathology features, including capillaritis, erythrocyte extravasation, and hemosiderin deposition.

Pigmented purpuric eruptions are rare. There seems to be no ethnic or gender predisposition, and most patients are in their 30s and 40s (see Table 168-1), but children may be affected.

There are three different views of the pathogenesis of pigmented purpuric eruptions. The first is that they are due to a disturbance or weakness of the cutaneous blood vessels, leading to capillary fragility and erythrocyte extravasation. However, this does not account for the inflammatory infiltrate common to these disorders. The second proposed mechanism is humoral immunity. This suggested pathogenesis is supported by direct immunofluorescent studies showing vascular deposition of C3, C1q, immunoglobulin M, or immunoglobulin A. However, several cases have not shown these deposits. The third proposed mechanism is cellular immunity.1,2 The infiltrate in pigmented purpuric dermatoses consists of lymphocytes, macrophages, and Langerhans cells. This inflammatory infiltrate leads to vascular fragility and subsequent leakage of erythrocytes. Aiba and Tagami used immunohistologic studies in eight cases of Schamberg disease to demonstrate that the dermal infiltrate was predominantly composed of helper–inducer T cells and OKT6-reactive cells,3 whereas the epidermis showed intercellular staining with human leukocyte antigen (HLA)-DR antibody and OKT6 antibody. Based on this study, they concluded that a cellular immune reaction, specifically the Langerhans cell, likely plays an important role in the pathogenesis.

Pigmented purpuric dermatoses may be induced by drugs (Table 168-2),4–17 but other causes have also been implicated (Table 168-3).18–25 The mechanism behind drug-induced or other causes may be immune-mediated; however, this is unproven. There could be familial involvement, as was shown in a handful of cases, with one report consistent with an autosomal dominant inheritance pattern.26 Gravity and increased venous pressure may account for the lesions localizing to the lower extremities.

Progressive Pigmentary Dermatosis (Schamberg Disease)

Schamberg first described in 1901 a pigmented eruption on the legs of a 15-year-old boy that consisted of irregularly shaped reddish-brown patches with “pin head sized reddish puncta, closely resembling grains of cayenne pepper.”27

Although described in children and adolescents, the average age of onset of Schamberg disease is in the fifth decade.28 The lesions tend to develop insidiously on either or both lower legs. Lesions can involve the trunk or the upper extremities (Figs. 168-1 and 168-2). Schamberg disease is generally asymptomatic and persistent. Remissions and flares can occur indefinitely.

Purpura Annularis Telangiectodes (Majocchi Purpura)

The original case of purpura annularis telangiectodes, described by Majocchi in 1896, was a 21-year-old man with annular patches of follicular and punctate reddish-brown macules, with telangiectasias and purpura on the lower extremities.29 The annular pattern is the distinctive characteristic of this subtype (Fig. 168-3). The individual lesions may have central hypopigmentation and slight atrophy, with peripheral telangiectasias. Linear and irregularly shaped patterns may also occur. The lesions most often present symmetrically on the lower extremities; however, the upper extremities and trunk may be involved. The lesions are asymptomatic and usually last several months with relapses and remissions. This subtype occurs more commonly in young adult females.

Pigmented Purpuric Lichenoid Dermatosis (Gougerot and Blum)

In 1925, Gougerot and Blum reported a pigmented eruption on the lower extremity of a 41-year-old man.30 The distinguishing feature of this subtype is the primary lesion, a reddish-brown polygonal or round lichenoid papule, in association with purpura or telangiectasia. Individual papules frequently coalesce into plaques with or without overlying scale. The term lichenoid describes the clinical appearance rather than a histologic feature. The color and morphology of the lesions can be mistaken clinically for Kaposi sarcoma (Fig. 168-4). Like the other subtypes, this eruption is found on the lower extremities and, occasionally, the arms. It occurs in males more often than females and has a chronic course.

Eczematid-Like Purpura of Doucas and Kapetanakis

Doucas and Kapetanakis reported a group of patients with an asymptomatic seasonal eruption occurring in the spring and summer.31 Its distinguishing quality is the mild scale overlying the typical patches and pinpoint erythematous macules. These spread rapidly over a period of 15–30 days, involving the legs and, occasionally, the upper body. This eruption fades without treatment over several months to years.

Itching Purpura (Disseminated Pruriginous Angiodermatitis)

The acute onset and widespread involvement of orange–brown to purpuric macules with severe pruritus distinguishes itching purpura (Fig. 168-5).32,33 It usually appears first on the lower extremities and may become generalized. This disorder also has a chronic course, but there can be spontaneous remissions. Middle-aged men are most commonly affected.

Lichen Aureus (Lichen Purpuricus)

Marten first coined the term “lichen purpuricus” in 1958,34 and Calnan later termed the same eruption “lichen aureus.”35 In this condition, lichen refers to the clinical and histopathologic descriptions. A dense, band-like, dermal, inflammatory infiltrate differentiates lichen aureus from the other pigmented purpuric dermatoses. Clinically, there are circumscribed areas of confluent gold to copper-orange to, less commonly, purple macules or papules (Fig. 168-6). Although these lesions may be intensely pruritic, they are typically asymptomatic. They are most commonly unilateral and localized on the lower extremities, but they can affect the forearms and trunk. This disorder has a predilection for young adults, with a peak incidence in the second and third decades. The lesions tend to be chronic, remaining stable or progressing slowly. Spontaneous resolution rarely occurs in adults, but in children the eruption may be self-limited.

Unilateral Linear Capillaritis (Segmental Pigmented Purpura)

Riordan et al reported a linear and pseudodermatomal distribution of pigmented purpura in four young men (average age, 22 years), which they called “unilateral linear capillaritis.”36 Both “segmental pigmented purpura” and “quadrantic capillaropathy” are considered variants of this linear pigmented purpura.37 The patients all had a macular, pigmented, unilateral eruption involving the foot, leg, or buttock. Clinically, the lesions most closely represented lichen aureus; however, the pathology did not show a lichenoid infiltrate. Furthermore, all four cases resolved spontaneously in approximately 2 years, unlike the typically chronic course of lichen aureus. Two more cases were reported in a young woman and man, both in their 20s and both with involvement of their arms. The lesion in the male was self-resolving, similar to previously reported cases, and the female's lesion resolved with PUVA.39 There are also several reported cases of segmental or zosteriform lichen aureus and Schamberg disease. Two cases have been associated with trauma, and one case preceded the development of localized morphea.40–51

Granulomatous Pigmented Purpura

Saito and Matsuoka first reported a granulomatous variant of pigmented purpuric dermatosis in 1996,52 and Wong reported two additional cases.53 The mean age of onset was 59 years; all patients were of Asian descent, and all occurred only on the dorsum of the feet. Additional cases have been reported in a Caucasian female with lesions on her lateral ankles54 and four more patients of Asian descent with involvement of the hands and wrists.55 The scope of this variant appears to be expanding. Histopathologic examination showed a dense mononuclear cell infiltrate with granulomas in the papillary dermis, thickened capillaries, vascular proliferation, melanophages, and hemosiderin deposits. The duration of the lesions ranged from 2 months to 20 years.

Pigmented Purpuric Dermatosis/Mycosis Fungoides Overlap

The first cases of pigmented purpura-like eruptions progressing to mycosis fungoides were reported in 1988 by Barnhill and Braverman.56 Further, the first patient diagnosed with lichen aureus in the United States was later diagnosed with mycosis fungoides. Some evidence supports the idea that lichenoid variants of pigmented purpuric dermatoses may be precursors of mycosis fungoides, with similar histologic findings and clonal populations of lymphocytes.57–64 Is there a relationship between the two disorders, or are these cases of mycosis fungoides merely mimicking pigmented purpura clinically? Although there is no clear connection between the two diseases, three different relationships have been reported: mycosis fungoides presenting as pigmented purpura, pigmented purpura evolving into mycosis fungoides, and pigmented purpura that simulates mycosis fungoides histologically. The latter may explain why similar treatments are used for both.65 In a study of T-cell clonality and markers, T-cell monoclonality of PPD was most likely to predict a progression to mycosis fungoides. The absence of certain T-cell markers was less reliable predictor. Histologic clues were subtle, including greater lymphoid atypia in the intraepidermal lymphocytes as opposed to the dermal lymphocytes, but both subsets of PPD had a degree of lymphoid atypia, lichenoid infiltrates, and epidermotropism.66 Differentiating between the two can be difficult, and clinical and histologic information, as well as immunophenotypic and genetic studies may be necessary.65,67 Pigmented purpuric dermatoses with large areas of confluence, reticular arrangements, a superimposed violaceous hue, or pruritus that have been present or relapsing for several years are suspicious for mycosis fungoides. There is predominance for adult males as well.56,68 Long-term follow-up of these patients is needed to determine if their lesions will evolve into mycosis fungoides.

The pigmented purpuric dermatoses share similar histopathology. In early lesions, a lymphocytic perivascular infiltrate is found in the papillary dermis with extravasated erythrocytes (Fig. 168-7). The epidermis may show spongiosis and parakeratosis, especially in the pigmented purpuric lichenoid dermatitis of Gougerot–Blum and in the eczematid-like purpura of Doucas and Kapetanakis. In older lesions, there is less inflammation, and extravasated red cells may no longer be present. Hemosiderin is deposited primarily in macrophages. In lichen aureus, the mononuclear infiltrate in the upper dermis is distributed in a band-like fashion with a grenz zone.

Diagnosis is generally made clinically and supported by histopathologic examination. No consistent laboratory abnormalities have been identified. The clinical measurement of capillary fragility by application of a sphygmomanometer (Hess test) does not appear to be reliable, because some reports show an increased capillary fragility in pigmented purpuric eruptions, and others were normal. Review of the patient's medical history, medications, and potential contact allergens is advised. Skin biopsy may be indicated to rule out vasculitis, especially if the lesions are papular. Mycosis fungoides should be considered if the lesions are chronic and unremitting.

(Box 168-1)

Treatment is often ineffective, and most treatments are anecdotal. If the eruption is induced by a drug or contact allergen, discontinuation of the causative drug or contact allergen can lead to complete resolution. However, residual pigmentation may persist for years. Oral bioflavonoid (rutoside, 50 mg bid) and ascorbic acid (500 mg bid) given to three patients with chronic pigmented purpura in an open trial led to clearance in all three patients within 4 weeks.69 Corticosteroids have been reported to be successful; in particular, triamcinolone spray or potent topical (fluorinated) steroids. Systemic corticosteroids and cyclosporine are often effective but are not indicated due to the benign nature of the disorder.70 With both topical and systemic steroids, recurrence of the lesions is the rule when steroids are discontinued. Treatment with topical pimecrolimus twice daily cleared lichen aureus lesions in a 10-year-old boy.71 In a pilot study, calcium dobesilate, 500 mg twice daily, was given to nine patients for 3 months.72 Seven patients had some mild-to-moderate improvement that was sustained at 1 year after cessation of therapy. Griseofulvin, 500 mg to 750 mg daily, improved existing lesions within a week and stopped new lesions within a mean of 33 days in an open trial of six patients.73 Colchicine, 0.5 mg twice daily, cleared a 28-year-old woman with recalcitrant Schamberg disease.74 Minocycline has also been reported to be beneficial. Methotrexate was reported to clear a patient with Majocchi purpura with just 15 mg weekly dosing for 4 weeks, although she had recurrence when the medication was stopped. Again, aggressive therapy is not often warranted for this benign condition, but this patient was treated for her severe burning and pruritus.75

Pentoxifylline, which inhibits T-cell adherence to endothelial cells and keratinocytes, may be helpful. A randomized, investigator-blinded trial compared pentoxifylline, 400 mg thrice daily, with topical betamethasone dipropionate cream, 0.05 percent twice daily, for 2 months. Patients treated with pentoxifylline had significantly greater improvement than those treated with the topical steroid. However, the response was not sustained after discontinuation of the medication.76 Psoralen and ultraviolet A light and narrow band ultraviolet B have both been reported to clear lesions.77–80 In one case, phototherapy was used to maintain disease suppression while tapering oral prednisolone. The patient remained clear on once every 2-week dosing, but had recurrence when UVB was completely stopped.81 In the second case, the patient cleared completely with just 30 UVB treatments and remained clear 8 months after stopping.82 The phototherapy-induced immunosuppression of cell-mediated response is the proposed mechanism.75 Photodynamic therapy has been reported as beneficial as it affects both immunomodulation and vascular destruction.83 Supportive stockings should be worn when lesions are on lower extremities.