Granulocytic sarcoma (chloroma), two years preceding myelogenous leukemia

Granulocytic sarcoma may develop during the course of, or as a presenting sign of, myelogenous leukemia. Rarely, an extramedullary neoplasm composed of poorly differentiated myelogenous cells occurs in patients without peripheral blood or bone marrow evidence of leukemia. A patient is described with granulocytic sarcoma who was 2 years from the time of initial diagnosis without evidence of leukemia, when the granulocytic sarcoma recurred. One month after this recurrence, the patient developed acute myelogenous leukemia. The literature is reviewed with emphasis on reports of granulocytic sarcomas occurring in the absence of myelogenous leukemia. A discussion of the differential diagnosis of granulocytic sarcoma and histiocytic lymphoma, based upon identification or exclusion of granulocytic differentiation in neoplastic cells, is presented. Granulocytic differentiation is indicated by the presence of eosinophilic myelocytes in the neoplasm, identification of an esterase in the cytoplasm of the malignant cells which is specific for neutrophilic precursors, or ultrastructural evidence of neutrophilic granulogenesis.