Diagnosis of granulocytic sarcoma facilitated by monoclonal antibodies.

A 36 year old woman presented with a nasopharyngeal tumour which was diagnosed and treated as diffuse large cell lymphoma. Twelve mth later the patient developed acute myeloid leukemia. At this stage, the original biopsies were reviewed and considered in retrospect to be granulocytic sarcoma on the basis of staining for chloracetate esterase and lysozyme. She achieved and maintained marrow and peripheral blood remission with chemotherapy, but developed several cutaneous nodules and 2 breast lumps. One breast lump was excised and was found, by the use of monoclonal antibodies, to carry myeloid markers. Thus monoclonal antibodies provided additional confirmatory evidence for the diagnosis of granulocytic sarcoma.