Primary cutaneous B-cell lymphoblastic lymphoma in an elderly man.

Precursor B-cell lymphoblastic lymphoma (B-LBL) is an uncommon high-grade neoplasm of immature B cells. It occurs predominantly in childhood with extranodal involvement such as skin and bone. Therefore, primary cutaneous involvement in elderly adults is a very rare manifestation of B-LBL. Here, we report a 78-year-old man with B-LBL presenting as a single cutaneous lesion which was immunohistochemically positive for leukocyte common antigen (LCA), CD79a, paired box 5 (PAX5), B cell lymphoma-2 (bcl-2), and terminal deoxynucleotidyl transferase (TdT) staining, but was without systemic involvement. The patient was treated using cyclophosphamide, adriamycin, vincristine, and prednisolone (CHOP), and achieved complete response (CR) at the first response assessment conducted after 3 CHOP cycles. After an additional cycle of CHOP treatment, radiotherapy was administered at a total dose of 3,600 cGy over 4 weeks. At the 21-month follow-up, he had maintained CR.