Author(s): Tameem Afroz1, Sistla Radha2

Prostate needle biopsies can pose a major diagnostic challenge when it comes to differentiating adenocarcinoma and its variants from its benign mimics. In needle biopsies, when the suspicious focus is small, morphological features may not suffice to differentiate it from its morphologic mimics like atrophy, basal cell hyperplasia, reactive inflammatory changes, seminal vesicles and adenosis. Immunohistochemical marker for basal cells, p63 and prostate cancer specific marker, Alpha-Methylacyl-CoA Racemase (AMACR) help in overcoming such diagnostic dilemmas.
We analysed 157 prostate core needle biopsies over a period of 2 years. Routine Hematoxylin and Eosin (H and E) sections and immunohistochemical markers for basal cells (p63) and prostate cancer specific marker (AMACR) were used. Prospective study was done on prostate needle core biopsies. Biopsy was done under ultrasound guidance with an 18-gauge needle. Biopsy was done in patients with raised serum PSA levels for exclusion of prostate carcinoma.
Over a period of two years, 157 prostate core needle biopsies were studied. 83 were benign lesions comprising 69 benign prostatic hyperplasias, five basal cell hyperplasias, four granulomatous lesions and three showed atrophic changes. Two biopsies morphologically resembled seminal vesicles. Prostate cancer specific marker, AMACR was negative in all, but two lesions. In these two lesions, it showed weak nonspecific staining. Basal cell marker p63 showed a continuous staining pattern highlighting the basal cells in all the 69 cases of benign prostatic hyperplasia, 5 cases of basal hyperplasia showed positivity in all the hyperplastic basal cells. In the two cases of seminal vesicles, it showed intense basal cell positivity. It showed a discontinuous pattern in two of the four granulomatous lesions and showed a weak, but a continuous staining pattern in the atrophic lesions. 74 were adenocarcinomas; the predominant Gleasons grade was (3+3). AMACR showed a sensitivity of 93% and a specificity of 97%. It had a positive predictive value of 0.97 and a negative predictive value of 0.94. Basal cell marker, p63 showed absent staining in all the 74 cases.
With the advent of prostate specific antigen serum screening and routine use of transrectal ultrasonography, there is a manifold increase in early detection of prostate adenocarcinomas. 18-gauge needle prostate biopsy under transrectal ultrasound guidance is a preferred method for detection of adenocarcinoma because it is associated with low morbidity and it provides information regarding the grade and extent of carcinoma. However, prostate adenocarcinoma has a number of morphological mimics with various architectural patterns. Immunohistochemistry plays a major role in overcoming diagnostic dilemmas encountered due to the presence of morphological and cytological equivocal features in small volume biopsies. To conclude, in morphologically equivocal glandular architectural patterns and cytological features, combination of immunostains highlighting the basal cells and prostate cancer associated marker can help the pathologist to arrive to a diagnosis on the limited amount of tissue available at his disposal. However, applications of both the immunostains have their inherent limitations.

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