Adenosquamous carcinoma of the prostate.

We present an unusual variant of prostatic adenocarcinoma with obvious squamous differentiation. The squamous component is represented by cells that contain vesicular or hyperchromatic nuclei and large acidophilic cytoplasm. We could demonstrate immunohistochemically the presence of prostate specific antigen (PSA) and glial fibrillary acidic protein (GFAP) in these tumour cells. Either in adenocarcinomatous or malignant squamous components, the prostatic epithelial cells showed the two markers, namely PSA, GFAP, which may reflect the multidirectional differentiation of these cells from a pluripotent origin.

Cells in various benign and malignant conditions of the human prostate express different antigenic phenotypes.

Prostatic epithelium basically consists of secretory-luminal, basal and endocrine-paracrine cells. Immunohistochemical procedures are frequently used for showing the cells reflecting different differentiations. In this study, 40 prostatic tissue specimens submitted to the Department of Pathology of Inönü University, Research Hospital, between 1991 and 1996 were examined. Half of the cases were diagnosed as cancer and the other half had various benign lesions. Of the cases 22.5% (n = 9) were needle biopsy material whereas the remainder, 47.5% (n = 19), were from prostatectomy and 30% (n = 12) were transurethral resection of the prostate (TURP) specimens. High molecular weight anti-cytokeratin antibodies (HMW anti-cytokeratin) stained basal cells both in all normal prostatic tissue and benign prostatic lesions, but in the majority of cancers (70%, n = 14) negative immunoreactivity was seen. Nevertheless, in some of the cancer cases (30%, n = 6) basal cell anti-cytokeratin staining was shown. Negative immunoreactivity with HMW anti-cytokeratin is important in distinguishing between malignant and benign lesions, whereas positive staining is not every time in favour of benign lesions. With the usage of prostate specific antigen (PSA) it was seen that all of the malignant and benign prostatic lesions stained positively. Basal cells in hyperplastic glands were not stained with this stain. Irregular, and in some areas, intense (PSA) immunoreactivity is present in precancerous and malignant lesions. Endocrine cells, which are represented with Chromogranin-A (Chr-A) immunoreactivity and reflecting neuroendocrine differentiation, are present in 75% (n = 15) of benign lesions and in 50% (n = 10) of cancer cases. It was thought that the lesser number of these cells in neoplastic lesions in comparison to the non-tumoral lesions is correlated with the disorder of mechanism that regulates the cell growth. Both in neoplastic and non-tumoral tissues the prostatic epithelial cells showed the three markers, namely HMW anti-cytokeratin, PSA, and Chr-A, which may reflect the multidirectional differentiation of these cells from a pluripotent origin.