Abstract
BACKGROUND: Relapse of acute lymphoblastic leukemia (ALL) occurring in the breast after allografting is extremely rare, with only 22 reported cases in the literature thus far. Further, the lack of a systemic analysis provides little information about this entity. We present a case of isolated extramedullary relapse from acute T lymphoblastic leukemia (ATLL) after allogeneic hematopoietic stem cell transplantation (HSCT). CASE PRESENTATION: A 32-year-old Chinese woman diagnosed with ATLL with myeloid antigen expression received HSCT from her human leukocyte antigen (HLA)-matched sister and presented with two lesions in her right breast 6 months later. Pathology investigation revealed breast relapse, with complete remission on the basis of bone marrow findings. Combined modality treatment including chemotherapy and local radiotherapy helped achieve complete remission with mild side effects. CONCLUSION: The findings from this case indicate that the breast is a potentially involved extramedullary site of relapse for ALL patients after HSCT. In the case of a newly developed breast lump in such patients, clinicians consider local relapse even if the bone marrow findings indicate remission. Combined modality treatment will contribute to better local control and improve prognosis.