Primary Anaplastic Lymphoma Kinase-Negative Breast Anaplastic Large Cell Lymphoma Without Breast Implant Association: A Case Report

BackgroundPrimary breast lymphomas are rare neoplasms, the majority of which are of B cell origin. Anaplastic large cell lymphoma of the breast is most commonly associated with breast implants; however, implant-unrelated tumors have also been reported. This case report describes a young patient diagnosed with primary anaplastic lymphoma kinase (ALK)-negative breast anaplastic large cell lymphoma in the absence of any history of breast implantation.Case ReportA 26-year-old woman presented with right breast pain and a palpable mass that had persisted for 3 months. Radiological evaluation revealed a complex cystic lesion suspicious for malignancy. Histopathological examination of the core biopsy specimen demonstrated diffuse neoplastic infiltration composed of large atypical cells with marked nuclear pleomorphism and increased mitotic activity. Immunohistochemical analysis showed strong CD30 positivity and focal epithelial membrane antigen expression, while ALK, keratin AE1/AE3, CD20, and Epstein-Barr virus (EBV) were negative. Following breast-conserving surgery, the final diagnosis was ALK-negative anaplastic large cell lymphoma.ConclusionThis report highlights that the development of anaplastic large cell lymphoma in the breast is not exclusively dependent on the presence of an implant and may occur in patients without any history of breast implantation. Given the nonspecific clinical and radiological findings, anaplastic large cell lymphoma should be considered in the differential diagnosis of breast masses, particularly those associated with cystic changes or chronic inflammatory processes. Definitive diagnosis requires thorough histopathological and immunophenotypic evaluation.