A 50-year-old man with transformed marginal zone lymphoma presented with intensely painful lesions on his left foot for 2 days. He noted a childhood history of plantar warts and believed these lesions to be identical in appearance. He did not recall any injury or unusual exposure. He had received his third cycle of R-CHOP (rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, prednisone) 2 weeks prior to presentation as well as an injection of granulocyte-colony stimulating factor. He was anticipating his fourth cycle of treatment the day of his presentation. He also complained of a pruritic rash on his left thigh that had started several days before the appearance of his plantar foot lesions. The patient was afebrile, and his vital signs were within normal limits. Physical examination revealed grouped, brown, flat-topped papules on his distal plantar left foot (Figure). It was exquisitely tender to palpation, and the patient was visibly uncomfortable when walking. He also demonstrated erythematous papules and plaques on his posterolateral thigh. A few areas had shallow erosions. Laboratory studies revealed pancytopenia, with a white blood cell count of 2800/μL, hemoglobin level of 11.6 g/dL, and a platelet count of 81 × 10 3 /μL. His lactate dehydrogenase level was elevated at 914 U/L, and results of his comprehensive metabolic panel were unremarkable.(To convert white blood cell count to ×10 9 /L, multiply by 0.001; to convert hemoglobin to grams per liter, multiply by 10; to convert lactate dehydrogenase to microkatals per liter, multiply by 0.0167.)Quiz at jamaoncology.com