Clinical and pathologic features of invasive micropapillary carcinoma

Invasive micropapillary carcinoma(IMC)of the breast is a rare subtype of breast carcinoma that has an extremely high incidence of lymph node metastases and poor clinical outcome. This histological subtype of breast carcinoma has remained unclear due to the rarity of cases. Many questions exist on the clinicopathological significance of this subtype, especially regarding prognosis.

We reviewed all 671 cases of primary breast carcinoma that were surgically resected at our institute between 1990 and 2004. Of these, 27 cases of invasive ductal carcinoma of the breast with a pure or partial micropapillary component were reported. The cases were analyzed using various parameters, including age at presentation, tumor size, tumor grade, presence of lymphatic invasion, and axially lymph node status.

The patients' age at presentation ranged from 31 to 74 years (mean 52.4 years). Tumor size ranged from 0.7 to 10 cm (mean 4 cm). 88.9% (24 of 27) of the cases had lymphatic invasion. Of cases who underwent with axillary dissection, 66.6% (18 of 27) had positive lymph nodes. Clinical follow up data were available for 17 cases with IMC for 1 to 72 months. Among these, 10 patients died from breast carcinoma within 5 years.

While our series is too small to make conclusions about the behavior of IMC, the difference in 6-year survival rate between the patients with IMC and those with breast carcinoma in general was statistically significant. Recognition of this distinctive and aggressive variant of infiltrating carcinoma is important because of its poor prognosis and high incidence of lymph node metastases.