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Case Reports

Abstract

Taxanes are chemotherapeutic agents that may cause phototoxic dermatitis (PD) and subacute cutaneous lupus erythematosus (SCLE), both of which may show interface dermatitis on histopathology, posing a diagnostic challenge. Here, we present a case where numerous epidermal ring mitoses serve as a clue leading to the correct diagnosis.

A 70-year-old female with breast carcinoma on paclitaxel presented with scattered erythematous, scaly and pruritic papules on sun-exposed areas of the face, arms and legs after 2 months of paclitaxel therapy. The clinical impression was taxane-induced PD versus taxane-induced SCLE.  Punch biopsy showed focal vacuolar degeneration of basal keratinocytes with scattered necrotic cells associated with a mild perivascular lymphocytic inflammatory infiltrate. There was no significant deep inflammation or dermal mucin deposition. Notably, numerous ring mitoses were present within keratinocytes in the lower half of the epidermis. Laboratory studies were negative for anti-SSA/RO antibodies. With clinicopathologic correlation, the diagnosis of taxane-induced PD was made.

Taxanes promote apoptosis of cancerous and other proliferative cells by binding to and disrupting microtubule assembly, resulting in atypical mitoses.¹ Atypical starburst-like or ring-like mitoses in basal and suprabasal keratinocytes have been reported as a direct cytotoxic effect by taxanes in PD as well as incidentally in benign neoplasms.^1,2 Both taxane-induced PD and SCLE may show interface dermatitis. However, taxane-induced SCLE does not typically show atypical mitotic figures, and is almost always associated with positive anti-SSA/RO antibodies.³ Awareness of epidermal ring mitoses may serve as a valuable clue for dermatopathologists to aid in distinguishing taxane-induced PD from taxane-induced SCLE.