Yolk Sac Tumor in Extragonadal Pelvic Sites

Abstract

We present the clinicopathologic features of 15 cases of extragonadal yolk sac tumor (EGYST) detected in female patients and reviewed at our institution from 1988 to 2016. We recorded: patient age, clinical presentation, tumor location, FIGO stage (where applicable), histologic patterns including presence/absence of Schiller-Duval bodies, other germ cell or somatic components, immunoperoxidase results, treatment, and outcome. Patients' ages ranged from 17 to 87 (median, 62) years and presentation included: abnormal uterine bleeding, 12; hematuria, 1; labial mass, 1; abdominal pain, 1. Primary sites were as follows: uterus (11), vagina (1), vulva (1), bladder (1), and peritoneum (1). Seven patients presented at FIGO stage III or IV. The following histologic patterns were observed: microcystic/reticular (7), glandular (8), solid (8), papillary (5), and hepatoid (1). An admixture of histologic patterns was present in 10 cases. Schiller-Duval bodies were seen in only 3 (23%) cases. Eight cases (46%), all uterine primaries, had associated somatic components, and 2 (15%) had a second germ cell component. In 13/14 (93%) cases, the yolk sac tumor component was either missed or misclassified as adenocarcinoma. Immunoperoxidase studies facilitated the diagnosis in all cases as follows: SALL4, 12/12; CDX2, 10/12; α fetoprotein, 7/14; glypican-3, 9/10; cytokeratin 20, 5/9 (rare cells); cytokeratin 7, 3/12 (nondiffuse); PAX8, 2/9 (variable expression). All patients received chemotherapy and all except 1 underwent surgical resection. Follow-up from 5 to 86 months was available for 13 patients: 5 died of disease, 6 are alive with disease, and 2 have no evidence of disease. EGYST arising in the female pelvis of peri/postmenopausal patients may be associated with a somatic component and represent either somatically derived YST or YST differentiation within a somatic carcinoma. EGYST in younger patients is likely a true germ cell neoplasm, and may respond to germ cell appropriate chemotherapy. The benefit of germ cell appropriate chemotherapy in somatically derived EGYST is less clear. Awareness that the presence of glandular or microcystic patterns may lead to under-recognition or misdiagnosis of EGYST in combination with immunomarkers for germ cell and yolk sac differentiation will facilitate the diagnosis.

Endometriosis‐related pathology: a discussion of selected uncommon benign, premalignant and malignant lesions

“…They are uncommon in individuals aged >40 years, although a second smaller peak occurs in postmenopausal patients. Uncommonly, ovarian YSTs occur in older adults, mostly associated with a somatic epithelial neoplasm . The somatic epithelial neoplasm may be of serous, endometrioid, mucinous or clear cell type, and the YST component is typically a glandular variant.…”

“…The somatic epithelial neoplasm may be of serous, endometrioid, mucinous or clear cell type, and the YST component is typically a glandular variant. Such neoplasms also, more uncommonly, occur in the uterine corpus . In the ovary, the most common somatic epithelial neoplasm is an endometrioid or clear cell carcinoma, often with associated endometriosis; sometimes only endometriosis is present (Figure A), and it is likely in such cases that a component of endometrioid or clear cell carcinoma has been present and totally overgrown.…”

“…Pathologists require a high index of suspicion to diagnose the YST component, because the morphology is typically that of a glandular variant with significant morphological overlap with various types of ovarian carcinoma (Figure B–D). There is also often significant immunophenotypic overlap with ovarian carcinomas, as the YST component may be positive for EMA, BerEP4, PAX8, and CK7, as well as the YST markers SALL4, α‐fetoprotein, glypican 3, CDX2, and villin; positivity for CDX2 and villin may result in an erroneous diagnosis of a metastatic colorectal adenocarcinoma . Particular diagnostic difficulties may arise when there is an admixture of clear cell carcinoma and YST, given the well‐known morphological overlap between these two tumour types …”

“…Uncommonly, ovarian YSTs occur in older adults, mostly associated with a somatic epithelial neoplasm. [49][50][51][52] The somatic epithelial neoplasm may be of serous, endometrioid, mucinous or clear cell type, and the YST component is typically a glandular variant. Such neoplasms also, more uncommonly, occur in the uterine corpus.…”

“…There is also often significant immunophenotypic overlap with ovarian carcinomas, as the YST component may be positive for EMA, BerEP4, PAX8, and CK7, as well as the YST markers SALL4, a-fetoprotein, glypican 3, CDX2, and villin; positivity for CDX2 and villin may result in an erroneous diagnosis of a metastatic colorectal adenocarcinoma. 49,50,52 Particular diagnostic difficulties may arise when there is an admixture of clear cell carcinoma and YST, given the well-known morphological overlap between these two tumour types. 50 These combined somatic epithelial carcinomas and YSTs should be distinguished from glandular variants of pure YST in which there is close morphological mimicry of an endometrioid carcinoma (sometimes with supranuclear or subnuclear vacuolation mimicking a secretory endometrioid carcinoma) or an intestinal-type adenocarcinoma.…”