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Abstract

Hypertrophic discoid lupus erythematosus is a distinct form of chronic discoid lupus, characterized by hyperkeratotic plaques typically observed over the face, arms, and upper trunk. Lesions frequently demonstrate reactive squamous atypia of the basal layer and may show histopathologic overlap with other more common cutaneous atypical squamoproliferative lesions.

A 50-year-old female with a 24-year history of systemic lupus erythematosus/discoid lupus erythematosus, chronic abdominal wall ulcer status post bowel transplant and catastrophic antiphospholipid syndrome on warfarin presented with a 1.1 cm painful swelling on the right extensor forearm of 1 week duration. Swelling was erythematous and warm to touch. Mupirocin and clobetasol was tried without improvement.

Histologic sections of shave biopsy demonstrated marked pseudoepitheliomatous hyperplasia, acanthosis with hypergranulosis, hyperkeratosis, vacuolar interface changes with varying numbers of apoptotic keratinocytes. Hyperkeratosis with follicular plugging associated with a dense lichenoid, perivascular and periadnexal lymphocytic inflammation was noted. Many plasma cells and scattered eosinophils were identified. Mild reactive squamous atypia was present. Special stains (PAS and GMS) were negative for fungal organisms. Treponema pallidum immunostain was negative and CD123 highlighted increased number of plasmacytoid dendritic cells (Figure 1).

A high index of suspicion for hypertrophic lupus erythematosus is essential to avoid overdiagnosis of squamous neoplasia, particularly in limited cutaneous biopsies in the absence of adequate clinical information.