Case Of The Month -September 2006

Biopsy Prostate:
The biopsy of the prostate shows necrotic material, focal calcification and a tumour. The tumour shows considerable biopsy artifact and a trabecular structure with crude collagenous trabeculae with squashed small cells in between. This is a malignant small blue cell tumour and is consistent with small cell carcinoma. Special stains show some positivity with Synaptophysin and necrotic material is positive and provides a background causing difficulty with interpretation. However, the tumour cells where clearly demonstrated shows some dot positivity adjacent to the nuclei. This is a malignant tumour, endocrine carcinoma.

Histology Diagnosis:" Neuroendocrine Carcinoma not otherwise specified."

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Synaptophysin is an excellent marker for neuroendocrine tumours and it is positive in this case. It is a glycoprotein and present in neuronal cells (Bibbo). CEA is also positive and it marks glycoproteins in embryonic endodermal tissue and most colonic carcinomas. The remaining markers used; S100, EMA, Chromogranin, CK20 and PSA are negative. S100 is positive in melanomas and sarcomas. EMA is positive in carcinomas (Koss). Chromogranin are secretory granules in neuroendocrine cells. CK20 is a marker for Transitional cell carcinomas (Rotem). NSE is another excellent marker for neuroendocrine carcinomas especially in situations where there is difficulty in diagnosing neuroendocrine tumours when lymphomas are suspected but this marker has not been used in this case. PSA (prostate specific antigen) reacts with benign and malignant prostate cells so it would be negative in neuroendocrine carcinomas.

Neuroendocrine carcinomas appear in different forms and they can be carcinoid tumours, large cell neuroendocrine carcinoma, small cell carcinomas or merkel cell tumours. Primary small cell and carcinoid tumours have been described in the prostate (De May).

No more than 5% of prostatic cancers are neuroendocrine carcinomas and they are more aggressive than adenocarcinoma of the prostate and they tend to metastasise rapidly to other organs. Some prostatic adenocarcinomas may have focal neuroendocrine differentiation. Small cell carcinomas can occur in the lung (oat cell carcinoma), cervix, bladder, thyroid, breast, skin, gastro-intestinal tract as well as the prostate.

Cytologically, small cell carcinomas are small pleomorphic cells with scanty cytoplasm, hyperchromatic nuclei and these cells are very fragile. Nucleoli are inconspicuous, nuclear molding occurs in high grade tumours and malignant cells are singly dispersed (Nicholson). Speckled or dusty chromatin patterns are often seen in small cell carcinomas. A bloody and necrotic background is often seen (Bui).