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ONCOCYTIC VARIANT OF PROSTATIC ADENOCARCINOMA - A CASE REPORT.

Byline: Muhammad Tahir Khadim, Usman Hassan, Ammara Ejaz and Nadira Mamoon

Article

INTRODUCTION

Prostatic adenocarcinoma has many histological variants including atrophic, pseudohyperplastic, foamy gland, colloid, signet ring, lymphoepithelioma like and sarcomatoid variant. Four additional variants have also been reported in isolated case reports1,2. These variants include oncocytic, giant cell carcinoma, neuroendocrine, prostatic intraepithelial neoplasia like variant, clear cell variant etc. As these variants are rare, prognosis and long term follow up is not studied enough3-5.

One such case of oncocytic variant of prostatic adenocarcinoma, a very rare variant is reported.

CASE REPORT

A 57 years old male presented in urology OPD with complaints of urgency, hesitancy, increased frequency and poor stream. His digital rectal examination was done, which revealed hard enlarged prostate. PSA levels were done which turned out to be more than ten times the normal value (40ng/ml). Transurethral resection of prostate (TURP) was planned. We received 30 grams of prostatic chips. All of the tissue was embedded. On microscopy, we found a tumour composed of large cells with granular and eosinophilic cytoplasm (Fig1, 2). Oncoytic cells comprised 100% of tumour cells. Cells had round to ovoid hyperchromatic nuclei arranged in solid sheets. Primary Gleason's grade was 5 and secondary grade was 4 with a total score of 9/10. About 80% of the chips were involved by tumour. No perineural invasion or lymphovascular invasion was seen. Immunohistochemistry marker for Prostate Specific Acidic Phosphatase (PSAP) (Fig 3) was applied by using Avidin Biotin Complex (ABC) method which revealed positive result.

DISCUSSION

Oncocytic variant of prostatic adenocarcinoma is a very rare variant and to date very few cases have been reported4,5. No prognostic significance has been associated with it because there are not enough cases to be followed up. Oncocytes are large cells with abundant eosinophilic granular cytoplasm. Oncocytes can be seen in benign as well as malignant conditions. In the parathyroids these are called as oxyphilic cells, hurthle cells in thyroid and oncocytes in pituitary, salivary glands, breast and kidney. Benign oncocytic tumours are common in salivary glands, endocrine organs and kidneys6. Malignant oncocytic tumours are rare, but they occur in thyroid as hurthle cell carcinoma. They can also occur in endocrine glands and salivary glands as well but there is no specific association proved for oncocytic tumours for either benign or malignant tumours7.

Oncocytic change can be seen in carcinomas showing some neuroendocrine differentiation4 . The reason for this granularity is the presence of neuroendocrine granules whereas in oncocytic variant of prostate and other oncocytic tumours of other site, it is due to increased mitochondria. In the past these oncocytes were considered as degenerated cells but now the finding that this change is due to increase mitochondria has proved that they are not degenerated cells. However ultrastructural and biochemical analysis have shown that these mitochondria are often abnormal and frequently show morphological alteration, by appearing swollen and abnormally shaped. This may be due to overcompensation by mitochondria to deal with oxidative stress8. Although this variant has been seen associated with higher gleason grade and metastasis, long term follow-up and detailed studies are still required to evaluate the prognostic significance of oncocytic variant of prostatic adenocarcinoma.

Whenever the oncocytic tumour in prostate is encountered, differential diagnosis should also include metastatic oncocytic tumours from other sites. Immunohistochemistry can be very helpful as PSA and PSAP are specific markers for carcinomas of prostatic origin.

Reference

1. Henderson JA, Espey DK, Jim MA, German RR, Shaw KM, Hoffman RM. Prostate cancer incidence among American Indian and Alaska Native men, US, 1999-2004. Cancer 2008; 113(5 Suppl):1203-12.

2. Ahmed Z, Azad NS, Rauf F, Yaqoob N, Husain A, Ahsan A et al. Frequency of primary solid malignant neoplasms in different age groups as seen in our practice. J Ayub Med Coll 2007; 19(3):56-63

3. Grignon DJ. Unusual subtypes of prostate cancer. Mod Pathol 2004;17(3):316-27.

4. Ordonez NG, Ro YG, Ayala AG. Metastatic prostatic carcinoma presenting as an oncocytic tumour.AM J Surg Pathol 1992;16:1007-12

5. Pinto JA, Gonzalez JE, Granadillo MA, Primary carcinoma of the prostate with diffuse oncocytic changes. Histopathology 1994;25:286-8.

6. Tahar GT, Nejib KN, Sadok SS, Rachid LM. Adrenocortical oncocytoma: a case report and review of literature. J Pediatr Surg 2008;43(5):E1-3.

7. Mai KT, Bicamumpaka C, Robertson SJ, Marginean CE, Belanger EC. Oncocytic renal cell carcinoma with immunohistochemical properties of renal oncocytoma. Pathol Res Pract 2009;205(2):119-24.

8. Elliott DD, Pitman MB, Bloom L, Faquin WC. Fine-needle aspiration biopsy of Hurthle cell lesions of the thyroid gland: a cytomorphologic study of 139 cases with statistical analysis. Cancer 2006;108(2):102-9.
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Author:Khadim, Muhammad Tahir; Hassan, Usman; Ejaz, Ammara; Mamoon, Nadira
Publication:Pakistan Armed Forces Medical Journal
Article Type:Clinical report
Geographic Code:9PAKI
Date:Jun 30, 2012
Words:778
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