Myeloid Sarcoma : Breast
Myeloid sarcoma rarely involves the breast, even though breast and testis are the two most commonly reported sites for acute myeloid leukemia (AML) relapse. The mere presence of a leukemic infiltrate in the breast does not qualify for the diagnosis of myeloid sarcoma. There needs to be effacement of tissue architecture. Most patients are premenopausal (below age 50).
In one metanalysis of 107 patients with myeloid sarcoma of the breast, 25% had no evidence of bone marrow involvement at the time of diagnosis, 22% had concurrent AML, 29% cases represented relapse of previously treated AML, and 24% represented relapse post-stem cell transplant.
The image shows diffuse infiltrate of medium to large mononuclear cells with effacement of the normal architecture.