[Adult T-cell leukemia/lymphoma, histologically presenting Ki-1 positive anaplastic large cell lymphoma]

A 48-year-old woman was admitted with neck tumors and cutaneous nodules. On the histological basis of the skin nodule biopsy, a metastatic anaplastic carcinoma was suspected. Immunohistochemical studies showed the presence of Ki-1 antigen, IL-2 receptor antigen, leukocyte common antigen (LCA), CD3 and CD4 on the tumor cells compatible with Ki-1 positive anaplastic large-cell lymphoma. This case was, however, finally diagnosed as adult T cell lymphoma (ATL) of a helper/inducer phenotype. She was born in Kagoshima. The serum anti-ATL associated antigen (ATLA) was positive. Southern blot analysis on the DNA extracted from the skin tumor cells showed a monoclonal integration of HTLV-1 proviral DNA. The results suggested that Ki-1 positive lymphomas may include a subset of ATL with a large-cell histology.