Background: The CD30 (Ki-1)-positive lymphoproliferative disorders show a non-epidermotropic infiltrate of large-sized pleomorphic T cells, being extremely rare those that develop from B cells.
Clinical case: A 51-year-old white man presented with a 8×10 cm lobulated scalp tumor that had developed during the previous 8 months. Histopathology demonstrated a proliferation of medium and large-sized non-anaplasic lymphocytes. The tumor cells (CD45+) expressed B phenotype (CD20+, CD3) and were CD30 (Ki-1) positive. The extension study revealed no extracutaneous involvement and the lesion resolved following chemotherapy. Two years later, after six cycles of chemotherapy that followed the CHOP protocol the patient remained asymptomatic.
Conclusions: We report a patient with a diffuse lymphoma of medium and large-sized B phenotype cells on the scalp that showed the unusual characteristic of being both non-anaplastic and CD30 (Ki-1) positive.