Interdigitating reticulum cell (IRC) tumor is a rare tumor arising from the antigen-presenting cell - interdigitating reticulum cell. A 41-year-old male presented with lumps in the left neck and bone pain. Further investigations revealed multiple left neck and para-aortic lymphadenopathy, and multiple bony lesions. Histological examination of the lymph node showed proliferation of unusual, large, round neoplastic cells mimicking large cell lymphoma. Immunophenotypic and ultrastructural studies confirmed this tumor to be arising from an interdigitating reticulum cell. A review of reported IRC tumors illustrates the variability of this tumor in clinical and pathological features, which differ from other dendritic reticulum cell tumors.
