Abstract
B-lymphoblastic leukemia/lymphoma (B-ALL) is a malignant neoplasm of immature B lymphocytes. Occasionally, B-ALL may exhibit morphological and immunophenotypic overlaps with other hematologic malignancies such as B-ALL with isolated myeloperoxidase (MPO) expression which may complicate diagnosis. BRCA1 and BRCA2 are tumor suppressor genes involved in homologous recombination and DNA repair. While germline mutations in these genes are well-established risk factors for breast and ovarian cancers, the association between BRCA1/2 mutations and hematologic malignancies remains underexplored. We present a rare case of B-ALL with isolated MPO expression, discovered incidentally in prophylactically resected ovaries of a patient with a germline BRCA1 mutation, and review the literature exploring this potential association.