Secretory Carcinoma Coexistent with Mucinous Carcinoma in the Breast

Secretory carcinoma and mucinous carcinoma were found to coexist in the breast of a 67 year old post menopausal woman, although the tumors were separated by a thin fibrous septum. Histochemically, intra‐ and extracellular secretory materials in both carcinomas were strongly positive for alcian blue, PAS and mucicarmine staining, but immunohistochemically negative for α‐ lactalbumin and CEA. Membrane‐bound intracytoplasmic vacuoles showing emiocytosis were observed in both the secretory and mucinous carcinomas by electron microscopy. No differences were observed between the tumor cells of secretory carcinoma and those of mucinous carcinoma by histochemistry, immunohistochemistry and electron microscopy. However, there were definite statistically significant differences in the results of morphometry of tumor cell nuclei. Secretory carcinoma is considered to be an anaplastic variant type of mucinous carcinoma. Acta Pathol Jpn 39: 593 598, 1989.