Abstract
Extramedullary relapses of acute lymphoblastic leukemia (ALL) are rare and usually localized in the central nervous system. We describe such an uncommon case of extramedullary relapse of ALL in the breast of a 44 year old female. The patient, who had been diagnosed with precursor B cell, Philadelphia positive (Ph+) acute lymphoblastic leukemia (ALL) 5 years before and had been in complete molecular remission for the last 19 months, was admitted to the hospital for investigation of a hard, non-tender lump in her right breast. Mammography detected a dense, ill-defined mass, whereas on grey-scale and power Doppler sonography, the appearance of the lesion was consistent with malignancy. Histopathologic and immunohistochemical examination of the specimen demonstrated a similar immunophenotype (CD20+, CD10+, Tdt+, CD3-) as this of the onset ALL cell population in the bone marrow.