Serous Carcinomas Initially Diagnosed on Colon Biopsies: A Case Series Highlighting the Role of p53 to Guide Management

Le résumé fourni par la source

This case series highlights the diagnostic challenge of Müllerian carcinoma presenting as colonic metastasis. The morphology, immunohistochemical work-up, and the utility of p53 immunohistochemistry in delineating between high-grade serous carcinoma and low-grade serous carcinomas are reviewed. Four patients initially presented with metastatic tubo-ovarian carcinoma in a colon biopsy between 2012 and 2023. Specimens and immunohistochemical stains were processed following routine clinical workflows. Colon biopsies in all patients showed a malignancy exhibiting papillary morphology (+/-psammomatous calcifications and "bottom-heavy" architecture) or poorly differentiated morphology. All patients were evaluated for metastasis by immunohistochemistry to include keratins (KRT7 and KRT20 or AE1/AE3), CDX2 or SATB2 (for gastrointestinal origin), and PAX8 (for Müllerian origin). Once Müllerian origin was established, further interrogation of the tumor with WT1, p53, and KI67 was essential to establish a diagnosis of high-grade serous carcinoma or low-grade serous carcinoma. Differing clinical management between high-grade serous carcinoma and low-grade serous carcinoma is summarized. Papillary morphology, "bottom-heavy" architecture, and psammomatous calcifications should prompt a metastatic work-up in colon biopsies. When a Müllerian site of origin is identified, a follow-up panel of markers-to include p53-should be used to distinguish between high-grade serous carcinoma and low-grade serous carcinoma to guide initial management options.

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