Use of the bone marrow imprint in the diagnosis of leukemic reticuloendotheliosis ("hairy cell leukemia").

Leukemic reticuloendotheliosis is a distinct entity, often misdiagnosed as chronic lymphocytic leukemia or lymphoma. The neoplastic cells have a specific tartrate-resistant acid phosphatase isoenzyme by which the diagnosis may be secured. Most individuals are leukopenic, and when, as in our case, rare or no circulating cells with tartrate-resistant acid phosphatase activity are found in the peripheral blood, an alternate site must be sought. Bone marrow aspirations often result in "dry taps," however, and cryostat sections of the bone marrow biopsy necessary to demonstrate tartrate-resistant acid phosphatase activity are involved and impractical to obtain for most laboratories. This report illustrates and recommends the simple technic of imprinting the core biopsy, which yields a satisfactory sample with which the specific cytochemical activity can be demonstrated.