Histiocytic lymphoma: a report of a case with an unusual phenotype

A 41-year-old female underwent a supraclavicular lymph node biopsy. Light microscopy showed a tumour with morphology suggestive of a malignant lymphoma arising from interdigitating reticulum cells (IDRC). Immunohistochemistry and enzyme histochemistry revealed the tumour cells not only to possess differentiation markers found on IDRCs but also markers characteristic of monocyte derived histiocytes. The implications of a neoplasm expressing this unusual phenotype are discussed in relation to the origin of histiocytes and their subsets.