Lessons From the Friday Unknowns The patient is an 18 years old man with neck lymphadenopathy. Histologic sections of the left neck biopsy specimen show extensive involvement by lymphoma. One small area in the specimen appears to represent residual lymph node. The neoplasm has a diffuse pattern and a prominent starry sky appearance. The neoplastic…

Lessons From the Friday Unknowns Histologic sections show lymphoma involving adipose tissue. No evidence of lymph node is identified. The neoplasm has two components. There is a prominent plasmacytic component between follicles and there is a smaller lymphoid component with a partial marginal zone distribution. The neoplastic plasma cells are generally small without marked atypia…

Lessons From the Friday Unknowns Histologic sections show fragments of salivary gland involved by lymphoma. The lymphoma cells are monotonous and small to intermediate-size with open to stippled chromatin with usually one nucleolus (blastoid appearance). Numerous mitotic figures and apoptotic bodies are present. Surrounding adipose tissue is also involved by the lymphoma. The lymphoma cells…

Lessons From the Friday Unknowns Histologic sections demonstrate two processes: One process affects lymphoid tissue and shows characteristic features of hyaline vascular type of Castleman disease. Specifically, lymphoid follicles are markedly increased and scattered throughout the cortex and medulla. Some follicles contain two or more small germinal centers (so-called “twinning”). Many germinal centers are…

Lessons From the Friday Unknowns Sections show needle-shaped fragments of lymphoma with large areas of necrosis.

Lessons From the Friday Unknowns Histologic sections show lymphoma associated with extensive sclerosis involving adipose tissue. No evidence of lymph node is identified.

Lessons from the Friday Unknowns Histologic sections show needle-shaped fragments of lymph node extensively replaced by lymphoma. Uninvolved lymph node shows follicles with germinal centers. The neoplasm has a diffuse pattern and is composed of scattered large neoplastic cells in a background of many eosinophils, small lymphocytes, histiocytes, and scattered plasma cells. Dense fibrous bands…