Primary Myeloid Sarcoma of the Breast: A Case Report and Review of Literature.

Myeloid sarcoma (MS) of the breast is uncommon. We report this case of a 29-year-old female presented with a breast lump that was diagnosed as hamartoma by radiology. The lump was removed surgically. Pathological examination revealed a malignant tumor composed of immature cells with eosinophilic cytoplasm and single or multiple nucleoli, diffusely infiltrating the mammary parenchyma and sparing a few ducts and lobules. Immunostaining revealed positivity for leukocytic common antigen, myeloperoxidase, and CD68, and focally positive for CD34 and CD117. The final diagnosis was released as primary MS of the breast. The patient was treated with radiotherapy and chemotherapy. Three consecutive bone marrow biopsies were negative for neoplastic infiltration.