Pure mucinous carcinoma of the breast: A clinicopathologic correlation study

Background: Pure mucinous carcinoma (PMC) of the breast has a better prognosis than does invasive ductal carcinoma not otherwise specified and is more prevalent in older patients. We investigated the correlation between prognostic indices and clinical outcome in this histologic subset. Methods: A retrospective review was done of patients with PMC treated between 1989 and 1996. Demographic data, pathologic indices of prognosis, axillary nodal status, and outcome were assessed. Results: Out of 6083 cases of breast carcinoma, 30 were PMC. Only 3 of 25 (12%) axillary dissections were positive. The average age of the group with positive nodes was 57 years, as compared to 69.5 years (95% CI; 63.24-75.76) in the group with negative nodes. All the tumors with positive nodes were aneuploid and had a high nuclear grade, compared to a 31.25% aneuploidy rate in the group without nodal disease (P = .058). Negative ER receptors were found in only 2 of 20 (10%) of the patients tested. Both had axillary disease (P = .016). Tumor size did not correlate with axillary metastasis. Two of the 29 patients died from unrelated diseases. The other 27 patients are alive with no evidence of disease. Conclusions: Axillary nodal disease is rare in PMC and correlates with a younger age, aneuploidy, high nuclear grade, or a negative ER receptor status. Sentinel lymph node biopsy may help identify the need for axillary dissection.