A Pilot Exploration of Clinicopathologic Features with Solid Papillary Carcinoma of the Breast.

e13056 Background: Solid papillary carcinoma of the breast (SPC) is classified as a special entity intraductal papillary tumor of breast tumors. Because of its rarity and specificity, its clinical behavior and its optimal treatment still remain controversial. The aim of this study is to analyze the clinicopathogical and immunophenotypic features of SPC, and to explore the choice of treatment options. Methods: A retrospective study of 56 cases of SPC was performed to analyze the clinicopathogical, immunophenotypic features and survival in these cases. All patients were followed up. Results: All cases were female with mean age of 65.36±14.06 years (range from 28 to 89 years), 85.7% of them were post-menopausal. There were 12 cases of in situ SPC, 9 cases of SPC with micro-invasion, 18 cases with invasive SPC, and 3 cases were accompanied by mucinous adenocarcinoma, 14 cases were accompanied with invasive ductal carcinoma. T1 accounted for 62.5% and the others were T2 (37.5%). 3 cases were found with lymph node metastasis. Approximately 62.5% of them were stage Ia, 33.9% were stage IIa, and 3.6% were stage IIb. Immunohistochemical analysis showed that most of the tumor cells expressed ER (96.4%) and PR (94.6%), all cases were CK5/6 negative. HER2 oncoprotein was positive in only 1 case. The average positive index of Ki-67 was 12.5%. About 78.6% of SPC were luminal A, and luminal B, HER-2 enriched and triple negative breast cancer were 17.9%,1.8% and 1.8%, respectively. The positive rates of Syn and CgA were 64.7% and 39.2%, respectively. The positive expression of P63, Calponin were 42.9% and 39.3% in the myoepithelial cells around tumor cell nests. All cases had follow-up data, the time of follow-up ranged from 6 to 61 months (average 18.6 months), 9 cases underwent chemotherapy, 7 cases underwent radiotherapy, 1 case underwent HER2 targeting therapy, and 47 cases underwent endocrine therapy (SERM,11; AI, 35; AI+OFS,1), all patients were disease-free so far. Conclusions: SPC of breast is a rare pathologic type of breast cancer, usually occurs in elderly females, with distinctive pathological features and immunophenotype. SPC often carries an indolent clinical behavior and its prognosis is better.