Pleomorphic Carcinoma in Transition to Papillary Carcinoma and Independent Mucinous Carcinoma of the Breast; A Report of the Rare Association

We report here a rare case of the breast of an elderly Japanese woman. The patient developed two nodules (A and B) in the left breast. The A nodule with a fibrous capsule constituted a pleomorphic carcinoma with bizarre giant cells and a well differentiated papillary carcinoma. The pleomorphic carcinoma was in transition to the papillary carcinoma suggesting that the pleomorphic carcinoma was transferred from the papillary carcinoma, possibly an encapsulated papillary carcinoma. Labelling index of Ki-67 of tumor cells of the pleomorphic carcinoma which consisted of a number of polyploid cells was much lower than the cells of the papillary carcinoma implying that some unknown etiology affecting cell cycle function such as through RB or p53 gene in the papillary carcinoma is an onset of the emergence of pleomorphic carcinoma in A nodule. The B nodule displayed the morphology of mucinous carcinoma with a large amount of extracellular mucin. At the periphery of the nodule, was also present another papillary carcinoma resembling that in A nodule. The mucinous carcinoma was also adjacent to the papillary carcinoma. It is assumed that development of the pleomorphic carcinoma and mucinous carcinoma is related to the papillary carcinoma in the two nodules. To the best of our knowledge, such case with three characteristic features of the breast carcinomas is extremely rare. Possible association and pathogenesis of these neoplasms is discussed.