A Case of Chronic Lymphocytic Leukemia with Intramammary Infiltration Requiring Differentiation from Ductal Carcinoma in Situ

Abstract

A 76-year-old woman with a 7-year history of chronic lymphocytic leukemia (CLL) was asymptomatic and was therefore only followed-up. However, an increased white blood cell count, particularly the percentage of lymphocytes, as well as systemic lymph node enlargement necessitated the initiation of chemotherapy. Screening mammography revealed focal asymmetrical densities in the right breast, and the patient was referred to our department for further evaluation. Ultrasonography revealed a geographic hypoechoic lesion (22 mm) in the C area of the right breast, suggesting ductal carcinoma in situ. We observed bilateral axillary lymph node enlargement ; however, the hilum of lymph nodes was preserved. Histopathological evaluation of a needle biopsy specimen revealed lymphocytic infiltration, and immunohistochemical analysis of lymphocytic surface markers revealed cells showing immunopositivity for CD20, CD5, and CD23, leading to a diagnosis of CLL with intramammary infiltration. Chemotherapy was initiated for CLL progression. The white blood cell count (specifically the percentage of lymphocytes) decreased together with disappearance of the intramammary lesion, 3 months after treatment initiation. The differential diagnosis should include extramedullary infiltration in patients with hematopoietic malignancy, who present with intramammary lesions.