Atypical Bilateral Hyperpigmented Macules on the Lower Legs Possibly Due to Cyclophosphamide

This case report discusses a 65-year-old Japanese man who developed atypical bilateral hyperpigmented macules on his lower legs, potentially linked to cyclophosphamide, a chemotherapeutic agent used in his lymphoma treatment. The pigmentation, characterized by brownish discoloration and black scales, appeared 3 weeks after starting the regimen and partially resolved after discontinuation, only to reappear with a similar treatment. Dermoscopic findings showed black dots consistent with hair follicles, and a biopsy indicated increased melanin. The exact mechanism is unclear, but it may involve direct stimulation of hair follicles by cyclophosphamide, warranting further investigation into this side effect.