CD5 negative, Cyclin D1-positive diffuse large B-cell lymphoma (DLBCL) presenting as ruptured spleen.

We present a case of diffuse large B-cell lymphoma CD5 negative, Cyclin D1 positive presenting as ruptured spleen in a 63-year-old man requiring emergent splenectomy. Tumor cells showed marked pleomorphism, anaplasia, and increased mitotic figures with positive Cyclin D1, BCL6, MUM1, P53, and a high MIB1 proliferative fraction. The patient received multiple therapies and ultimately died. This case raises the differential diagnoses of pleomorphic mantle cell lymphoma and other aggressive lymphomas with pleomorphic, anaplastic, and Reed-Sternberg-like cells.