Myeloid sarcoma involving the breast

Abstract

Context: Myeloid sarcoma is a neoplasm of myeloid cells that can arise before, concurrent with, or following acute myeloid leukemia. Rarely, it can also occur as an isolated mass.

Objective: To describe the clinicopathologic features of 6 patients with myeloid sarcoma involving the breast.

Design: Clinical information for all 6 patients was obtained from the medical record. Routine hematoxylin-eosin-stained slides; naphthol AS-D chloroacetate stain; and immunohistochemical stains for myeloid, B-cell, and T-cell antigens were prepared.

Results: There were 6 women with a median age of 52 years (range, 31-73 years). Two patients presented with isolated tumors of the breast, with no history or subsequent development of acute myeloid leukemia. In 3 patients, the breast tumors represented relapse of acute myeloid leukemia. One patient who presented initially with myeloid sarcoma involving the breast, skin, and spleen was lost to follow-up. Histologically, these tumors were classified as well differentiated (n = 3), poorly differentiated (n = 2), and blastic (n = 1). Naphthol AS-D chloroacetate esterase was positive in all 3 cases assessed. Immunohistochemistry showed that myeloperoxidase (n = 5) and CD43 (n = 3) were positive, and CD3 (n = 5) and CD20 (n = 5) were negative in all cases assessed. Lysozyme was positive in 4 (80%) of 5; CD117 was positive in 2 (67%) of 3; and single cases were positive for CD45 (1/3), TdT (1/2), CD79a, and the PAX5 gene product.

Conclusions: Myeloid sarcoma involving the breast is uncommon. In the literature, as in this study, these tumors most often represent relapse or the initial presentation of acute myeloid leukemia. However, 2 of the cases we report presented with isolated masses, without a history or subsequent development of acute myeloid leukemia at last follow-up. Immunohistochemical studies are extremely helpful for recognizing isolated myeloid sarcoma.