CASE STUDY #2
CLINICAL PRESENTATION:
Fifty-Eight year-old male presenting with nausea and weight loss starting a few weeks ago. His total weight loss was 30 pounds. The patient was scheduled for EGD and colonoscopy. His EGD was unremarkable. The colonoscopy showed localized area of nodular mucosa in the distal rectum. Biopsies were obtained and sent to the lab.
HISTOLOGICAL FINDINGS:
Sections showed benign colonic mucosa with hyperplastic changes. The lamina propria was infiltrated by nest of malignant cells with occasional signet ring forms and increased mitotic activity.
IMMUNOHISTOCHEMICAL STAINS:
CDX2: positive in the colonic crypt epithelium but negative in the tumor cells.
NKX3.1 and PSA: positive in the tumor cells.
DIAGNOSIS:
Poorly differentiated adenocarcinoma with signet ring features.
Primary origin: Prostate (by direct extension or metastasis).
DISCUSSION:
Clinical and endoscopic correlation play an important role in the evaluation of GI biopsies. When evaluating malignant tumors in colonic biopsies, the pathologist looks for in-situ component to confirm that the tumor is arising from the colon. This is frequently noted in colonic adenocarcinoma arising in tubular or tubulovillous adenomas. In this case, a non-colonic primary was suspected when no adenomatous tissue was seen. The endoscopic impression of “nodular” mucosa suggested a submucosal process. Efficient immunohistochemistry work-up was helpful in ruling out colonic origin by the negative CDX2 stain and confirming the prostatic origin with the positive prostatic markers NKX3.1 and PSA.
REFERENCES:
1- Warner JN, Nakamura LY, Pacelli A, Humphreys MR, Castle EP. Primary signet ring cell carcinoma of the prostate. Mayo Clin Proc. 2010;85(12):1130–1136. doi:10.4065/mcp.2010.0463
2- Gök A, Tuygun C, Akmansu M, et al. Primary Signet Ring Cell Carcinoma of the Prostate: A Rare Case Report. J Clin Med. 2018;7(8):218. Published 2018 Aug 15. doi:10.3390/jcm7080218
