title: Primary Endometrial Yolk Sac Tumor With Endodermal-Intestinal Differentiation Masquerading as Metastatic Colorectal Adenocarcinoma.
abstract: Yolk sac tumors (YSTs) with a somatic glandular pattern can be difficult to recognize histologically because they reproduce developing intestinal, hepatic, or lung tissue and can express markers such as CDX2 and TTF1. We report an unusual case of a primary endometrial YST showing florid endodermal-intestinal differentiation in a 63-yr-old woman with a history of colorectal adenocarcinoma. Histologically, the tumor exhibited a glandular and papillary architecture and showed widespread immunoreactivity for CDX2 and focal staining for CK20 and CEA, mimicking metastatic colorectal carcinoma on biopsy. The presence of subnuclear cytoplasmic clearing and positive staining for germ cell markers, however, pointed toward a diagnosis of primary endometrial YST, and this was supported by the radiologic and the subsequent pathologic finding of a primary endometrial-based lesion. YSTs in this age group usually arise in association with somatic tumors and in this case a small focus of coexistent endometrioid adenocarcinoma was identified within the uterus. Despite surgery and adjuvant chemotherapy, the patient showed disease progression with liver and lung metastases 6 mo postoperatively.
authors.affiliation: Department of Cellular Pathology (S.D.), John Radcliffe Hospital Gynaecological Oncology Unit (K.H.), Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford Department of Pathology (W.G.M.), Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Damato
authors.forename: Krishnayan
authors.initials: K
authors.lastname: Haldar
authors.forename: W Glenn
authors.initials: WG
authors.lastname: McCluggage
mesh_terms: D000230:Adenocarcinoma / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism*; D000071616:CDX2 Transcription Factor / Q000378:metabolism; D018269:Carcinoma, Endometrioid / Q000175:diagnosis* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D018450:Disease Progression; D018240:Endodermal Sinus Tumor / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D016889:Endometrial Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D004717:Endometrium / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053554:Keratin-20 / Q000378:metabolism; D008875:Middle Aged; D009362:Neoplasm Metastasis; D010051:Ovarian Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; C507499:KRT20 protein, human; D053554:Keratin-20