Apalutamide‐associated skin rash in patients with prostate cancer: Histological evaluation by skin biopsy

Abstract

Introduction Apalutamide‐associated skin rash is a more common adverse event in the Japanese population than in the global population. However, its mechanism remains elusive, and limited histopathological information hampers further understanding. Case presentation Case 1: a 71‐year‐old man with metastatic castration‐sensitive prostate cancer developed a skin rash after 70 days of apalutamide treatment. Case 2: a 71‐year‐old man with non‐metastatic castration‐resistant prostate cancer developed a skin rash after 71 days of apalutamide treatment. In both cases, the skin rash presented as a slightly exudative erythema. The histology showed spongiosis of the epidermis and perivascular and interstitial infiltration of lymphocytes and eosinophils in the upper dermis without necrotic keratinocytes. Conclusion Apalutamide‐induced skin rashes can involve an eczematous reaction clinically and histologically.

Keywords

• adverse event
• apalutamide
• eczematous drug eruption
• prostate cancer
• skin rash