Hairy cell leukemia with bone marrow hypoplasia.

This article reviews the authors' experience with hairy cell leukemia to determine the incidence of hypoplastic marrows in this disease and the utiity of embedding marrow biopsy specimens in plastic, which allows the sections to be stained for tartrate-resistant acid phosphatase (TRAP). It was found that the presence of hairy cells in the peripheral blood, marrow aspirate, or both established the diagnosis in eight of 11 patients; in the remaining three patients, the marrow biopsy specimen was necessary for definitive diagnosis. The bone marrow was markedly hypocellular in three patients, including one in whom the marrow morphologic results were essential for diagnosis. Embedding the marrow biopsy specimen in plastic and staining the sections for TRAP was noted to be a useful technique in establishing the diagnosis of hairy cell leukemia. In all cases in which this was performed, the authors found abundant TRAP-positive cells in the marrow biopsy specimen; even in those cases with markedly hypocellular marrows, this technique revealed the presence of hairy cells. In one patient, TRAP staining of the marrow biopsy specimen proved essential for definitive diagnosis. The authors concluded that the occurrence of marrow hypocellularity is not rare in patients with hairy cell leukemia and that TRAP-staining of plastic-embedded marrow biopsy specimens is a helpful and sometimes essential technique in diagnosing hairy cell leukemia.