Granulocytic sarcoma presenting as a solitary nodule of skin in a patient with Waldenstrom's macroglobulinemia. An immunohistochemical and electron-microscopic study.

While he was being treated for Waldenstrom's macroglobulinemia, a 75-year-old man developed an enlarging forearm skin nodule. On biopsy, the lesion appeared to be a malignant lymphoma. The tumor cells were negative for immunoglobulins but positive for lysozyme and alpha-1-antitrypsin. Therefore, the lesion was diagnosed as histiocytic lymphoma. Nine months later, an ipsilateral axillary lymph node biopsy revealed a small focus of tumor identical to that of the skin lesion. Three months after the lymph node biopsy, the patient developed acute myeloid leukemia. A reevaluation of the electron micrographs of the skin and lymph node lesion showed primary lysosomal granules within the tumor cell cytoplasm consistent with a diagnosis of leukemic infiltrates (granulocytic sarcoma); additionally, the naphthol AS-D chloracetate esterase activity of the skin lesion was positive, supporting the diagnosis of granulocytic sarcoma. This report shows that if not suspected, granulocytic sarcoma is difficult to diagnose in nonleukemia patients.