Cyclin D1 Negative Mantle Cell Lymphoma

From the Friday Unknowns

The patient presented in 2020 with diffuse lymphadenopathy and massive splenomegaly. Flow cytometry immunophenotyping of peripheral blood showed a CD5-positive lambda-positive B-cell population. FISH on this blood specimen showed ATM deletion and loss of chromosome 13.

The lymph node biopsy specimen shows extensive replacement by lymphoma. The neoplasm is mostly diffuse with minor nodular areas. The neoplastic cells have mostly classic cytologic features but there is some pleomorphism.