Mucinous (colloid) breast cancer: clinical and mammographic findings in 10 patients

The purpose of this study was to review the clinical and mammographic findings in patients with mucinous (colloid) breast cancer.

We retrospectively reviewed the pathology reports of 444 women with breast cancers diagnosed between May 1988 and October 1993 after mammographic evaluation. Of these, 10 women 31-88 years old (mean, 67 years) had pure mucinous adenocarcinoma of the breast. We reviewed the clinical and mammographic findings in these 10 patients.

Three patients (30%) had palpable masses. Mammographic abnormalities were detected on screening studies in the seven patients (70%) who were asymptomatic. The mammographic findings included poorly defined, lobulated, solitary masses in seven patients, poorly defined, clustered masses in two patients, and a well-circumscribed mass in one patient. No tumors had calcifications as the primary finding, and only one tumor had a few scattered, round, calcifications associated with clustered masses. Two patients had areas of noncomedo ductal carcinoma in situ without calcifications adjacent to the invasive mucinous adenocarcinoma. The tumors were 7-35 mm in diameter. No metastases were found in the axillary lymph nodes in the eight patients in whom biopsies of these nodes were done.

The most common and distinctive mammographic feature of mucinous breast carcinoma is a poorly defined, lobulated mass. The absence of axillary nodal metastases, even in patients with large palpable tumors, supports the notion that biologically, mucinous carcinomas are slower growing, less aggressive tumors than infiltrating ductal carcinomas not otherwise specified.