Does a case report show myeloid sarcoma relapse appearing in the breast for Acute Myeloid Leukemia?

Myeloid sarcoma is a rare solid tumor that can occur outside the bone marrow in people with acute myeloid leukemia (AML). It can appear in many parts of the body, including the breast. A recent case report describes a patient who had myeloid sarcoma in the nasal cavity, was treated successfully, and then developed a new myeloid sarcoma in the breast 6 years later. This shows that breast relapse is possible, even after a long disease-free period.

What the research says

A 2025 case report describes a 68-year-old woman who initially presented with a nasal mass that was diagnosed as myeloid sarcoma ³. She achieved complete remission after radiotherapy and chemotherapy. Six years later, she developed a painful right breast nodule. Initial imaging suggested a primary breast cancer, but after surgical removal, immunohistochemical analysis showed the tumor was actually a relapse of myeloid sarcoma ³. This case highlights that myeloid sarcoma can mimic other cancers and that breast relapse can occur years after initial treatment. Other case reports also describe rare sites of myeloid sarcoma relapse, such as the conjunctiva of the eye ¹⁰ and the testicles ¹¹, but the breast is an uncommon location. The case emphasizes the importance of using specific markers (like myeloperoxidase) to correctly diagnose myeloid sarcoma when it appears in unusual sites ³.

What to ask your doctor

• Could a new breast lump in someone with a history of AML be a sign of myeloid sarcoma relapse?
• What tests (such as biopsy with immunohistochemistry) are needed to distinguish myeloid sarcoma from primary breast cancer?
• How often should patients with a history of myeloid sarcoma have follow-up imaging or exams to check for relapse?
• What treatment options are available if myeloid sarcoma relapse occurs in the breast or other extramedullary sites?