Unusual Presentations of Gynecologic Tumors: Extragonadal Yolk Sac Tumor of the Vulva

Abstract

Extragonadal germ cell tumors are uncommon, and although they morphologically resemble their gonadal counterparts, unexpected gonadal presentation increases the potential for erroneous diagnoses. Yolk sac tumor is a malignant germ cell tumor characterized by an extraembryonic yolk sac line of differentiation, and relative to other germ cell tumors, is characterized by varied and diverse histologic patterns. When occurring outside of typical age parameters or in extragonadal locations, the histologic variability of yolk sac tumor and its tendency to mimic somatic tumors pose diagnostic challenges. Because extragonadal yolk sac tumor of the vulva is very rare, with only isolated case reports and small series in the literature, it is often not considered in the differential diagnosis. As both prognosis and management of yolk sac tumor differ significantly from those of somatic tumors, accurate diagnosis is essential. This review discusses histologic features of extragonadal yolk sac tumor, addresses somatic tumors arising in the vulva for which yolk sac tumor may be confused, and provides guidance with respect to the use of immunohistochemistry in the diagnosis of yolk sac tumor.

Vulvar Yolk Sac Tumors Are Somatically Derived SMARCB1 (INI-1)-Deficient Neoplasms

“…tumor. 5,7,9,14,[41][42][43][44] Previously, most vulvar cases were presumed to have arisen from misplaced germ cells which were deposited in the vulva during embryogenesis. 9,41 We have presented the clinicopathologic and molecular features of 3 vulvar neoplasms with yolk sac tumor-like morphology and loss of SMARCB1 immunohistochemical staining and posit that these tumors represent somatically derived tumors with yolk sac tumor-like morphology, not extragonadal germ cell neoplasia.…”

Primary Extragonadal Yolk Sac Tumor Arising from the Urachus: A Case Report with Literature Review

“…[8] Instead, a panel of IHC stains is necessary and should include a pluripotent germ cell marker (SALL4), antibodies associated with YST (AFP and glypican-3), and labels present in more differentiated yolk sac tumors (cytokeratin (CK) AE1/AE3, CK20, CDX2 and villin). [8,11] In this case, lesional cells were moderately stained with AFP; strongly postive for SALL4, CK AE1/AE3, PLAP; and focally reactive for CD117. Tumor cells were negative for OCT-4 and CD30.Due to www.pacificejournals.com/apalm eISSN: 2349-6983; pISSN: 2394-6466 its variety of histologic patterns, the differential diagnosis of extragonadal yolk sac tumors (EGYSTs) in pelvic or peritoneal locations include carcinomas primary to a specific site, such as clear cell carcinoma, endometrial cancer, or carcinosarcoma of the uterus, adnexal tissue or peritoneum; adenocarcinoma (with or without intestinal differentiation) of the urachus or bladder; and primary or metastatic gastrointestinal carcinoma.…”

“…aberrant differentiation of somatic cells, (4) derivation from pluripotent stem cells within a somatic tumor, (5) origination from residual fetal tissue following incomplete abortion (uterine-based lesions), and (6) metastases from an occult gonadal primary malignancy. [11] Given the midline tumor location, the sex of the patient and the absence of either a testicular or other occult primary, we speculate that theories 1-3 are applicable; nevertheless, a definitive characterization is not possible. YSTs comprise approximately 20% of high-grade GCTs and are the most common malignant germ cell tumors in infants and children <4 years of age and represent 3-5% of pediatric tumors.…”

Nonsquamous Lesions of the Vulvar Skin and Subcutaneous Tissue: A Review (Part 1)

“…In primary yolk sac tumor of the vulva, misplaced/ aberrant germ cell migration along the gubernaculum is the leading hypothesis. 40 Teratoma is an embryonal neoplasm consisting of the 3 germ layers. 41 EPIDEMIOLOGYAND CLINICAL PRESENTATION.…”