What is your diagnosis?

Discussion and answer

Plasma cell myeloma with "anaplastic" features involving the lymph nodes

Sections from the lymph node show a diffuse infiltrate of pleomorphic large cells. These cells have vesicular chromatin and one to several prominent nucleoli with fairly abundant clear to slightly amphophilic cytoplasm. There is evidence of necrosis and apoptotic bodies in the background and many mitoses are found. The neoplastic infiltrate is extending into the perinodal fat tissue.

The CD138 is strongly positive, while CD20, LCA, CD3, S100, AE1/3 cytokeratin and vimentin are negative. The histologic and immunophenotypic features consistent with plasma cell myeloma involving the lymph node.