Leukemia Cutis
A 65-year-old man presented to the dermatology clinic with a 5-day history of a painful rash on his hands and elbows. He had no other symptoms. Physical examination showed erythematous and purplish plaques on the dorsa of both hands and elbows in a symmetric distribution. Laboratory examinations showed a white-cell count of 16,000 per cubic millimeter (reference range, 4200 to 10,200) and a platelet count of 70,000 per cubic millimeter (reference range, 145,00 to 348,000). Skin biopsy of a lesion on the left elbow revealed a perivascular lymphocytic infiltrate in the dermis, with positive staining for myeloperoxidase, CD123, Ki67, and CD68. A diagnosis of leukemia cutis was made, and the patient was urgently referred to the oncology clinic. A bone marrow biopsy revealed 15 to 20% blasts and molecular mutations in ASXL1, NRAS, SRSF2, and TET2. The patient received a diagnosis of chronic myelomonocytic leukemia and underwent stem-cell transplantation. Two weeks after the transplantation, the patient’s skin changes had resolved, and the cancer has been in remission since.