SAN FRANCISCO A rare case of relapsing leukemia cutis appeared only in the skin, in a patient with no evidence of circulating leukemia whose bone marrow appeared to have responded completely to previous treatment.
A 45-year-old patient had undergone chemotherapy in 2007 for myeloid leukemia, Dr. George Elgart and his associates wrote in a poster presented at the annual meeting of the American Society of Dermatopathology. Although he responded initially, he was lost to follow-up before completing therapy. After he returned to care and resumed chemotherapy, remission was confirmed by peripheral blood and bone marrow analyses.
He subsequently developed multiple skin lesions that were nonspecific on clinical exam but that suggested a systemic process. The lesions increased rapidly in number and size. Because of the patient's history, "the diagnosis was not challenging," reported Dr. Elgart, professor of dermatology and cutaneous surgery at the University of Miami.
The lesions first presented as subcutaneous nodules, some in bizarre shapes, such as a plaque shaped like a question mark. Many of the lesions eventually ulcerated or developed an adherent thick crust. A punch biopsy of one of the lesions showed a dramatic infiltrate to all margins of the specimen.
Immunopathology can be helpful but is highly variable in the skin manifestations of hematologic processes and is complicated by the inconsistency of myeloid leukemia immunohistochemistry, Dr. Elgart noted. In this case, review of the primary histology helped to direct the immunohistochemical evaluation.
The punch biopsy specimen was positive on immunostaining for CD56 and CD177 but negative for myeloperoxidase and CD34. The cells had a decidedly geometric configuration and appreciable cytoplasm. They appeared unconstrained by the surrounding dermal anatomy and extended to track among the collagen bundles in a manner parallel to that of metastatic carcinoma. In contrast, a recent review by other investigators reported the most sensitive markers to be lysozyme and CD68.