Microscopic description:

Resembles lung small cell carcinoma

Typical features of small cell carcinoma, including high mitotic rate, frequent apoptotic bodies, crush artifact and DNA encrustation of blood vessel walls (Azzopardi phenomenon) are present

IHC: positive synaptophysin, Ki67 (90%), negative chromogranin 

Discussion:

Pure or combined with ordinary ductal adenocarcinoma

Diagnosis restricted to cases having either pure or mixed with an adenocarcinoma component, where the cells resemble small-cell carcinoma of the lung (and elsewhere) histologically

Very aggressive, cannot monitor with PSA (unreliable)

Serum PSA levels are often not elevated

Survival usually less than 1 year

Positive IHC stains: Synaptophysin, NSE, TTF1, CD56

Chromogranin may be +/-

Negative IHC: PSA, PSAP

References:

Bleichner, J. C., Chun, B., & Klappenbach, R. S. (1986). Pure small-cell carcinoma of the prostate with fatal liver metastasis. Archives of pathology & laboratory medicine, 110(11), 1041–1044. https://pubmed.ncbi.nlm.nih.gov/3022668

Agoff, S. N., Lamps, L. W., Philip, A. T., Amin, M. B., Schmidt, R. A., True, L. D., & Folpe, A. L. (2000). Thyroid transcription factor-1 is expressed in extrapulmonary small cell carcinomas but not in other extrapulmonary neuroendocrine tumors. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc, 13(3), 238–242. https://doi.org/10.1038/modpathol.3880044

Wang, W., & Epstein, J. I. (2008). Small cell carcinoma of the prostate. A morphologic and immunohistochemical study of 95 cases. The American journal of surgical pathology, 32(1), 65–71. https://doi.org/10.1097/PAS.0b013e318058a96b

Hiroshima, K., Iyoda, A., Shida, T., Shibuya, K., Iizasa, T., Kishi, H., Tanizawa, T., Fujisawa, T., & Nakatani, Y. (2006). Distinction of pulmonary large cell neuroendocrine carcinoma from small cell lung carcinoma: a morphological, immunohistochemical, and molecular analysis. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc, 19(10), 1358–1368. https://doi.org/10.1038/modpathol.3800659

CASE IMAGES