Extramedullary Relapse of B Cell Acute Lymphoblastic Leukemia in Bilateral Breasts Treated with Whole Breast Radiotherapy.

Isolated extramedullary relapse of acute lymphoblastic leukemia (ALL) in the breast is extremely rare. We herein report a case of a 38-year-old female with B cell ALL, who had isolated extramedullary relapse initially in the left breast and subsequently in the right breast, 3 and 4 years, respectively, after hematopoietic allogenic stem cell transplantation. She was successfully salvaged with bilateral whole breast radiotherapy, 24 Gy/12 fractions/2.5 weeks. This brief report highlights the importance of awareness of extramedullary leukemic relapse in the breast as one of the differential diagnoses of breast masses in the context of ALL. Since these tumors are extremely radioresponsive, radiation therapy is a safe and effective treatment option for isolated extramedullary relapse of ALL in the breast.