MLT students

Hairy cell leukemia
Definition, histopathology and peripheral smear

Definition
Hairy cell leukemia (HCL) is a rare, indolent lymphoproliferative neoplasm of mature B cells with a distinct clinical presentation that includes peripheral blood cytopenias, splenomegaly and a small number of circulating neoplastic cells with hair-like cytoplasmic projections.

Histopathology
Extensive marrow fibrosis as demonstrable by reticulin stain; however, neoplastic hairy cells, as described in the peripheral blood description, can be seen. (first image)

Peripheral smear
Pancytopenia with rare hairy cells that are medium in size with moderately abundant pale blue cytoplasm, reniform nuclei, open chromatin, absent nucleoli and a characteristic serrated cytoplasmic border. (last three images)