mucinous carcinoma of the breast mucinous carcinoma of the breast mucinous carcinoma of the breast is a form of mucinous carcinoma and a breast cancer type. rare cases of this carcinoma have been diagnosed in men (see male breast cancer). mucinous carcinoma of the breastother namescolloid carcinoma of the breastgross pathology (upper left) of biopsies of mucinous carcinoma shows gelatinous areas. histopathology shows clusters or nests of tumor cells floating in pools of extracellular mucin.specialtyoncology, breast surgerysymptomscolloid carcinoma, gelatinous carcinoma, mucoid carcinoma, mucinous adenocarcinoma histopathologic types of breast cancer, with relative incidences and prognoses, with "mucinous (colloid) carcinoma" at right.