Ductal Carcinoma in situ and Lobular Carcinoma in situ Arising in a Phyllodes Tumor

Abstract

A 44-year-old woman was admitted to the hospital because of a rapidly enlarging mass in the right breast. A well-demarcated tumor measuring 9.0×7.0 cm was noted, mainly in the outer quadrants of the right breast. A core needle biopsy revealed findings suggestive of a borderline phyllodes tumor. Simple mastectomy and axillary lymph node sampling were performed under the tentative diagnosis of phyllodes tumor. Histopathological examination of the resected specimen revealed that the tumor was a borderline phyllodes tumor, with coexisting ductal carcinoma in situ and lobular carcinoma in situ. Ours is the first case report from Japan of ductal carcinoma in situ and lobular carcinoma in situ arising in a phyllodes tumor. While it is an extremely rare occurrence, phyllodes tumor can be associated with breast carcinoma, therefore, serial sectioning of the specimen is recommended.