An extragonadal yolk sac tumor presumed to be of postmeiotic germ cell origin by genetic zygosity analysis via single nucleotide polymorphism array

Abstract

An extragonadal yolk sac tumor (YST) is a rare malignant germ cell tumor that usually occurs in childhood. The pathogenesis of extragonadal YST remains largely unknown, especially with regards to its cell of origin. Herein, we report a case of extragonadal YST arising in the uterine round ligament. A 31‐year‐old Japanese woman, para 2, underwent partial resection of a left‐sided, 5‐cm, solid inguinal mass. Intraoperative findings showed enlargement of the uterine round ligament in the inguinal canal. Pathological evaluation diagnosed the mass as YST with a mature teratoma (MT) component. The preoperative α‐fetoprotein level was markedly elevated, at 24 790 ng/mL. Postoperative magnetic resonance imaging revealed a right ovarian MT and a 3‐cm mass remaining in the left lower abdominal wall. The patient underwent total abdominal hysterectomy, bilateral adnexectomy, and left inguinal mass resection. We sampled three frozen tissues (YST, right ovarian MT, and left normal ovary) and performed a single nucleotide polymorphism (SNP) array. Pathological evaluation revealed remnant extragonadal YST in the left inguinal region. The SNP array demonstrated a completely homozygous YST genotype. Copy number variations were gains of 1p, 1q, 2p, 3p, 7p, 8p, 10q, 14q, 18p, 20q, Xp, and Xq and losses of 12q, 20p, and Xq. The right ovarian MT and left normal ovary were partially homozygous and heterozygous, respectively. The evidence suggests that this neoplasm is presumed to be a postmeiotic germ cell origin.

Single nucleotide polymorphism array and cytogenetic analyses of ovarian teratomas in children

“…These markers sample dozens loci of the genome and they are limited in reflecting the zygosity status of the entire genome. More recently, whole genome single nucleotide polymorphism (SNP) array has been used in studies of ovarian teratomas, 14‐16 and whole exome sequencing was also used to look at mutation and zygosity in teratomas 17 . Both of them have high resolution and can identify zygosity reliably.…”

Yolk Sac Tumor of the Omentum: A Case Report and Literature Review

“…One of the distinguishing features between somatic and germline origin is zygosity. Complete homozygosity suggests postmeiotic germ cell origin even in adult patients [ 13 ].…”

Clinical characteristics and risk factors analysis for the recurrence of pelvic endodermal sinus tumors

“…The sites of occurrence can be divided into gonads (ovaries, testes) and non-gonads (sacrococcygeal, mediastinal, retroperitoneal, lung, oral cavity, pineal gland and vagina) [2][3][4]. According to literature reports, extragonadal germ cell tumors account for approximately 1%-5% of all germ cell tumors [1,5,6].…”