Abstract:

Background and purpose: Solid papillary carcinoma (SPC) is an uncommon histological pattern accounting for <1% of breast carcinomas. It is a distinctive form of papillary carcinoma characterized by closely apposed expansile, cellar nodules. The present study aimed to investigate the clinicopathologic features, immunophenotype and prognosis of SPC of breast. Methods: We retrieved the data of 32 cases of SPC of the breast from pathology files, and determined the expressions of ER, PR, C-erbB-2, p63, Calponin, CK5/6, Ki-67, Syn and CgA by pathohistological observation and immunohistochemical examination. Results: All the patients were females with a mean age of 67.3 years. The clinical features were a palpable mass or bloody nipple discharge. The tumor was observed as a whitish-grey or yellowish-brown, fleshy firm or soft, nodular circumscribed mass on gross examination. Microscopy showed solid and papillary area inside the capsule wall and that fine delicate fibrovascular septa were discovered amid the solid proliferation. The tumor cells were oval, polygonal, spindled or signet ring-like with abundant eosinophilic cytoplasm and contained mildly to moderately pleomorphic nuclei. Immunohistochemically, all tumor cells were strongly positive for ER and PR (++-+++), negative for C-erbB-2 and all cases were negative for CK5/6, p63 and Calponin in the cellular nodules. The positive expression rates of Syn and CgA were 68.8% and 78.2%, respectively. The average positive rate of Ki-67 in tumor cells was 7.5% (2%-20%). Twenty-seven patients were available for followup examination from 6 to 84 months and 25 patients were alive and disease free. One patient had tumor recurrence, and was alive after reoperation. Another patient died of the tumor metastasis. Conclusion: SPC is predominantly found in elderly females with distinctive pathological features and immunophenotype. SPC often carries an indolent clinical behavior, and even if accompanied by infiltration, very rare cases have recurrence and metastasis after resection, so its prognosis is better.

Key words: Breast neoplasms, Solid papillary carcinoma, Neuroendocrine carcinoma, Pathologic diagnosis