Intraductal (intracystic) papillary carcinoma of the breast and its variants: a clinicopathological study of 77 cases.

The clinical and pathological features of 77 cases of intraductal (intracystic) papillary carcinoma (IPC) of the breast are reported. It should be recognized as an intraductal carcinoma variant and distinguished from invasive papillary carcinoma. Intraductal papillary carcinoma remains a difficult diagnosis as there are four different epithelial growth patterns any of which may predominate. Low grade nuclear features occur in one third of cases, a so-called "stratified spindled cell" epithelial proliferation with bland morphology occurs in one quarter of cases, and a dimorphic population of malignant cells, which may in part be confused with myoepithelial cells, occurs in one quarter of cases. The 77 cases studied were from the 10-year interval 1970 to 1979. The effect on prognosis of cytoarchitectural features, duct wall and stromal invasion, and associated intraductal carcinoma were evaluated. The contribution of immunohistochemistry to the diagnosis using antibodies to smooth muscle actin, S-100 protein, and CAM 5.2 was examined. The 10-year survival rate was 100%, and the 10-year disease-free survival rate was 91%. Mastectomy had been performed in 72% of patients. Three of the patients developed metastases; two were alive with tumor and one died of other causes. Six patients had local recurrence in the chest wall; one was alive without disease, two were alive with tumor, and three died of other causes. An associated intraductal carcinoma of usual nonnecrotic or comedo type was present in 40% of all cases. When IPC recurred or metastasized, it did so as invasive papillary carcinoma in six of seven cases. Stromal invasion was found in 13 patients. Local recurrence developed in two of these. Invasion was not seen in any of the three patients who developed metastases. However, this may be a function of sampling as there was an average of 5.2 tumor sections per case. Patients with low grade tumors had no recurrence or metastasis, and in the absence of invasion may be treated by local excision. Patients with higher grade tumors have an increased risk of recurrence and metastasis.