Clinicopathologic Discordance in Atypical Unilateral Dorsolateral Lichen Simplex Chronicus Mimicking Kaposi Sarcoma

A Diagnostic Challenge

Abstract

Background: Lichen simplex chronicus (LSC) is a chronic inflammatory dermatosis arising from repetitive mechanical trauma that sustains an itch-scratch cycle and leads to epidermal hyperplasia and dermal fibrosis. Although frequently encountered in dermatologic practice, dorsolateral involvement is rare and may assume exaggerated morphologic features that simulate infectious or malignant processes.

Objective: To report an unusual case of unilateral dorsolateral LSC clinically mimicking Kaposi sarcoma and to emphasize the indispensable role of clinicopathologic correlation in atypical acral dermatoses.

Methods: Comprehensive clinical evaluation with histopathologic examination and repeat biopsy confirmation.

Results: Histopathology demonstrated irregular acanthosis, compact orthokeratotic hyperkeratosis, hypergranulosis, pseudoepitheliomatous hyperplasia, papillary dermal fibrosis with vertically oriented collagen bundles, and dense lymphocytic infiltrates. These findings confirmed LSC. Due to persistent clinical concern for neoplasia, repeat biopsy was performed and reconfirmed the diagnosis. Combination corticosteroid-based therapy led to marked clinical improvement.

Conclusion: This case underscores how atypical anatomic presentations of otherwise common inflammatory dermatoses can create substantial diagnostic ambiguity and clinical uncertainty. When lesions arise in unusual locations or exhibit overlapping morphologic features, reliance on clinical impression alone may be misleading. In such scenarios, histopathologic evaluation serves as the definitive diagnostic anchor. Moreover, when clinicopathologic discordance persists, repeat biopsy and careful correlation between clinical findings and microscopic features are essential to establishing an accurate diagnosis.