Prostate Carcinoma with Amphicrine Features: Further Refining the Spectrum of Neuroendocrine Differentiation in Tumours of Primary Prostatic Origin?

Abstract

Objective

The current WHO classification categorises high grade neuroendocrine (NE) carcinomas of the prostate into small cell and large cell types. A distinct form of carcinoma demonstrating synchronous dual exocrine and NE differentiation, termed amphicrine carcinoma, has been described at various other sites, primarily within the gastrointestinal tract. In this study, we describe the clinicopathologic features of a series of metastatic prostatic carcinomas with amphicrine features.

Methods

Five cases of high grade prostatic carcinoma (PCa) demonstrating an amphicrine immunohistochemical phenotype were prospectively collected.

Results

Serum prostate specific antigen (PSA) level at diagnosis ranged from 38-992ng/ml (median 200ng/ml). All 5 patients had metastatic disease; 4 at initial presentation. Microscopically, the tumours demonstrated a solid/nested growth pattern composed of cells with amphophilic cytoplasm, vesicular nuclei and macronucleoli. Morphologic features of small cell or large cell NE carcinoma were absent. Compared with conventional high grade PCa, the tumour cells displayed greater nuclear pleomorphism, brisk mitotic activity and a high Ki67 proliferation index (median 50%). All cases demonstrated immunohistochemical positivity for PSA, androgen receptor (AR) and prostatic specific acid phosphatase (PSAP) combined with diffuse or confluent/non-focal positivity for chromogranin-A and synaptophysin. Two hormone-naive cases showed a clinical response to androgen deprivation therapy.

Conclusion

This series highlights a previously undefined, clinically aggressive variant of PCa exhibiting dual exocrine and NE differentiation, for which we are proposing the term PCa with amphicrine features. Increased recognition of these tumours may lead to a better understanding of their biology and ultimately improve their clinical management.

This article is protected by copyright. All rights reserved.

http://ift.tt/2u9ePDs