Lymphocytic lymphoma simulating hairy cell leukemia: a consideration of reliable and unreliable diagnostic features.

Morphologic, immunologic and functional characteristics of an unusual poorly differentiated diffuse lymphocytic lymphoma closely resembling hairy cell leukemia are presented and the diagnostic features of the latter disease are reviewed. The malignant cells morphologically resembled hairy cells at the light as well as electron microscopic level. They had surface characteristics of both T and B lymphocytes, were phagocytic, and adhered to glass. The spleen was smooth and resembled that seen in hairy cell leukemia. Although there was a predilection for the red pulp of the spleen, there was a lack of characteristic pseudosinus formation, and areas of predominantly white pulp involvement considered characteristic of lymphocytic lymphoma were found after extensive examination.