Immunohistochemical differential diagnosis of granulocytic sarcomas and malignant lymphomas on formalin-fixed material.

A panel of monoclonal antibodies (anti-CD45 [common leukocyte antigen], Ki-B3, L26, MT1, UCHL1, anti-CD15 [X-hapten], anti-neutrophil granule protein elastase [NP57]), anti-lysozyme, and the naphthol-ASD-chloroacetate reaction were applied to two cases of granulocytic sarcoma (GS) for evaluation of their utility in differentiating GS from malignant lymphoma. Lysozyme and naphthol-ASD-chloroacetate esterase were found to be the most reliable markers for detection of the myeloid nature of the tumour cells. GS infiltrated solely the mucosa of the nasal cavity in one case, while in the other it involved both the nasal cavity and maxillary sinus with simultaneous eruptions on the skin of the trunk. In both cases, peripheral blood and bone marrow findings were inconspicuous at the time of diagnosis of GS.