From legs to abdomen: Navigating the uncharted territory of pigmented purpuric dermatosis in a middle-aged female

Introduction

Pigmented purpuric dermatoses encompass a range of conditions identifiable by a unique purpuric rash predominantly observed on the lower extremities. Although these disorders display morphological variations, their histopathological characteristics are shared, rendering them indistinguishable. ¹ The condition is marked by capillary inflammation, involving the extravasation of erythrocytes and haemosiderin-laden macrophages into the skin. Clinically, it presents as petechiae or ecchymosis, manifesting as papules or plaques with hues ranging from red and purple to yellow or brown, reflecting the deposition of hemosiderin within the dermis. ²

The clinical presentation of PPD encompasses five primary categories: progressive pigmentary dermatosis, commonly known as Schamberg disease (the most prevalent type); pigmented purpuric lichenoid dermatosis of Gougerot and Blum; purpura annularis telangiectodes of Majocchi; eczematid-like purpura of Doucas and Kapetanakis; and lichen aureus. ³

PPD is a benign skin condition linked to exposure to various medications and chemicals. While different mechanisms have been suggested, the precise aetiology remains unidentified. ⁴

Case report

A 40-year old woman presented with multiple flat, asymptomatic red lesions on both lower limbs and abdomen persisting for the previous 15 days. The lesions, initially appearing on the legs, progressed to involve the thighs and later the abdomen. She denied any preceding febrile episodes, drug intake, or pre-existing illness, and there was no similar complaint in her family.

Upon physical examination, nonblanchable erythematous macules of 0.5–2 mm size were observed, coalescing into patches on the lower limbs and abdomen (Fig. 1). A few ill-defined light brown and orange-brown colored patches were also seen. No oedema was noted. Differential diagnoses of generalized pigmented purpuric dermatosis, cutaneous vasculitis, thrombocytopenic purpurae, maculopapular viral exanthema and maculopapular drug rash were kept in mind. Dermatoscopy revealed red spots and globules arranged on a coppery-red pigmented background. Intervening irregular brown pigmented network, annular and comma-like vessels were also noted (Fig. 2). A provisional diagnosis of generalized pigmented purpuric dermatosis was therefore made. Blood investigations including platelet counts and coagulation profile were unhelpful. The diagnosis was confirmed by histopathological examination of punch samples from the lesions, which showed acanthosis and focal parakeratosis in the epidermis, non-homogenous melanin deposition in the rete ridges, along with diffuse and perivascular lymphocytic infiltration in the papillary dermis. Dilated and tortuous blood vessels were observed with extravasation of red blood cells. Lymphocytes exhibited exocytosis into the epidermis (Fig. 3). The features were consistent with generalized pigmented purpuric dermatosis. The clinico-dermoscopic and histopathological correlation in PPD has been tabulated in Table 1. ⁵

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Figure 1.

Multiple nonblanchable erythematous macules of 0.5–2 mm size, coalescing into patches on the lower limbs (1a) and abdomen (1b).

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Figure 2.

Dermoscopy revealed reddish-brown patches (black arrow), red dots and globules (yellow circle) and comma shaped vessels (blue circle) over a coppery-red background (Hiene Delta 20T dermatoscope, 10x).

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Figure 3.

Histopathological analysis revealed acanthosis and focal parakeratosis in the epidermis. The dermis shows diffuse as well as perivascular infiltration by lymphocytes along with extravasation of red blood cells (Hematoxylin and Eosin, 40x).

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Table 1.

Clinical-dermoscopic and histopathological correlation in Pigmented Purpuric Dermatosis (PPD)[5].

Clinical	Dermoscopy	Histopathology
Erythematous macules and patches	Red dots and globules	Vertically aligned or tortuous and engorged capillaries
Light brown patches	Irregular brown pigment network	Non-homogenous presence of melanin in rete ridges
Not appreciable clinically	Annular and comma-like vessels	Perivascular pattern of lymphocytic infiltration
Orange-brown colored patches	Coppery-red pigmentation	Diffuse lymphocytic infiltration in the upper dermis

Oral vitamin C and other antioxidants (hesperidin and diosmin) were administered twice daily, with emollients and narrow-band UVB phototherapy three times a week for 15 days. Slow improvement in erythema was observed, so the same treatment was continued for an additional 15 days, with gradual but complete clearance of the lesions.

Discussion

In Schamberg disease, distinct cayenne pepper-like lesions localized to the lower extremities are evident. Majocchi purpura, also known as purpura annularis telangiectodes, is characterized by clinical features such as reddish annular patches or plaques observed on the buttocks, trunk, and proximal extremities. The Gougerot-Blum variant is identified by lichen planus-like papules with superimposed purpura. Lichen aureus presents as golden, slightly indurated scaly solitary plaques over the medial malleolus, usually affecting young to middle-aged adult males. Eczematous changes within a context of purpura characterize the condition known as eczematoid pigmented purpuric dermatosis of Doucas and Kapetanakis. ⁶

Several associations have been noted with venous stasis, diabetes mellitus, and rheumatoid arthritis. Certain drugs including non-steroidal anti-inflammatory agents, sedatives, antihypertensives, antihistaminics, and lipid-lowering agents may be trigger factors, leading to lymphoid atypia. ⁶

Differentiating between generalized PPD and potential mimics such as vasculitis, and thrombocytopenic purpura is crucial. Skin biopsy plays a pivotal role. Leucocytoclastic vasculitis often manifests with dermatologic symptoms, emphasizing the importance of systemic symptom evaluation. Thrombocytopenic purpura, identified by a platelet count < 100–150 × 10⁹/L, is another vital differential.

Currently, PPD lacks a standardized treatment. Discontinuation of implicated drugs may lead to spontaneous improvement. ⁴ The following complications are associated: (a) persistent or recurrent, leading to chronicity and discomfort; (b) scratching may lead to infection, which warrant additional treatment; (c) psychosocial impact if lesions are widespread or persistent, may lead to emotional distress, and heightened self-consciousness.