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.

Yolk sac tumours of the female genital tract in older adults derive commonly from somatic epithelial neoplasms: somatically derived yolk sac tumours

“…A review of the literature identified 11 previously reported cases of primary endometrial YSTs, four of which were associated with a somatic epithelial neoplasm. 44 In two of our cases, the YST component was a purely hepatoid variant; one of these was a pure YST and the other was admixed with a HGSC. These cases were reported originally as a pure ovarian hepatoid carcinoma and a combined HGSC and hepatoid carcinoma.…”

“…[35][36][37][38][39][40][41][42][43] These are thought to have a similar histogenesis to the corresponding ovarian neoplasms. We recently reported one such case (case 18 in this series 44 ). This occurred in a 63-yearold woman with a history of colorectal carcinoma.…”

“…Positive staining for germ cell markers (SALL4, AFP, glypican 3), however, pointed towards a diagnosis of primary endometrial YST, and a small component of endometrioid adenocarcinoma was identified in the subsequent hysterectomy. A review of the literature identified 11 previously reported cases of primary endometrial YSTs, four of which were associated with a somatic epithelial neoplasm …”

Intestinal differentiated mucinous adenocarcinoma of the endometrium with sporadic MSI high status: a case report

“…Regarding the age of our patient, the possibility of yolk sac tumour seems to be implausible [20]. Nevertheless, some authors argue for the existence of yolk sac tumour of the endometrium in postmenopausal patients based on AFP expression [17, 21]. However, it has been shown that gastric and colorectal cancers can express AFP as well, which can be used as serological biomarker [22, 23].…”

Endometrial Yolk Sac Tumor with Omental Metastasis

“…We have identified only a few published reports of endometrial YSTs in PubMed, affecting patients aged 17 to 65 years. [ 1 2 ] Among the cases, the most frequent symptom was abnormal vaginal bleeding, but presurgical endometrial biopsy allowed correct diagnosis of YST in only five cases. YSTs can show variable presentation under a microscope, and pathologists may have difficulty in differentiating microcystic or endodermal sinus-like structures from clear-cell carcinoma.…”