[Isolated granulocytic sarcoma in the breast].

A 16-year-old female, who was diagnosed as having non-Hodgkin lymphoma following a biopsy of a tumor of her right breast, was admitted to our hospital. The diagnosis made by the referring hospital was not reconfirmed because of the pathological findings with suspicion of sarcoma. As another tumor appeared in the contralateral breast 10 days after hospitalization, a second biopsy of the tumor was performed. Touch preparations of the tumor were positive for myeloperoxidase and naphthol AS-D chloroacetate esterase staining. The diagnosis of granulocytic sarcoma (GS) was made. No abnormalities were found in the peripheral blood and bone marrow at this time. Chromosomal examination of the bone marrow was normal. The number of copies for WT-1 mRNA was high both in the bone marrow cells and the tumor cells. The expression of WT-1 mRNA in peripheral blood was not detected. She was treated with the same protocol as for acute myelogenous leukemia and the breast tumor disappeared. The titer of WT-1 mRNA in bone marrow slightly decreased but remained high. Taken together, these findings suggest that the GS seems to be bone marrow origin and the monitoring of WT-1 mRNA may be useful for early diagnosis of any relapse.