Early Bilateral Gonadoblastoma in a Young Child with Mosaicism for Turner Syndrome and Trisomy 18 with Y Chromosome

Abstract

Mosaic Turner syndrome (TSM) commonly occurs in the form of 45,X/46,XX and 45,X/46,X,i(X)(q10). Mosaicism for a Y chromosome, 45,X/46,XY, has been well documented and is associated with increased risk of gonadoblastoma (GB). To date, there are only six reported cases of TSM with a trisomy 18 karyotype, and only two of these were phenotypically female with 45,X/47,XY,+18 karyotype. We present the case of a phenotypically female infant born with dysmorphic features. G-banded karyotype and interphase FISH of blood showed 45,X in 95% and 47,XY,+18 (trisomy 18) in 5% of cells analysed. However, interphase FISH of buccal cells showed only the presence of the 45,X cell line. Due to the presence of Y chromosome material, elective gonadectomy was performed at 13 months of age. There were bilateral streak ovaries with early evidence of GB bilaterally, a rudimentary uterus and bilateral fallopian tubes with unilateral ectopic adrenal tissue identified histologically. Interphase FISH of the gonadal tissue was similar to the blood findings with 45,X in 86% of cells and 47,XY,+18 in 14% of cells analysed. This case highlights a rare karyotype of TSM and trisomy 18 in the same patient and is the first reporting the associated finding of bilateral GB.

Gonadectomy in conditions affecting sex development: a registry-based cohort study

“…In some of these conditions that are associated with a disorder of androgen synthesis, the indication for early gonadectomy was the avoidance of pubertal virilisation in an XY girl. Given that more children with XY DSD are being raised as boys ( 12), there is a greater prospect of preserving gonadal function and fertility (16,17) and there is a greater emphasis on the patient's own views on gonadectomy (4,18,19), there has been an increased emphasis on retaining gonads until the age when patients with DSD can decide for themselves (20). Mitigation of tumour risk was the commonest reported indication for performing gonadectomy and therefore as expected, in the current study, the number of cases that actually had any evidence of tumour development was very small.…”

Genitourinary manifestations of hereditary cancer predisposition syndromes in children

“…Mosaicism in Turner syndrome with presence of Y chromosome material-estimated to occur in 6-9% of patients with Turner syndrome (89)-increases the risk of developing gonadoblastoma and dysgerminoma (90). The overall risk of developing gonadoblastoma is estimated to be 15-33% in patients with these Turner syndrome features (91). Gonadoblastoma tends to be diagnosed early in life in such patients, so it is recommended that patients with 45X/46XY karyotypes undergo prophylactic gonadectomy (92).…”