Thyrotoxic adenoma followed by atypical hyperthyroidism due to struma ovarii: clinical and genetic studies

Abstract

Objective: Atypical forms of hyperthyroidism represent a diagnostic challenge for clinicians. Struma ovarii is an ovarian teratoma and constitutes a rare cause of ectopic thyroidal hormonal production. We describe a case of struma ovarii that combined two different sources of hyperthyroidism in the same patient and report genetic studies in order to contribute a better understanding of the autonomy and tumorigenesis of the struma ovarii. Case report: A 73-year-old nulliparous woman presented a thyroid toxic adenoma that was successfully treated with 10 mCi radioiodine. Unexpectedly, a new onset of hyperthyroidism prompted us to look for a second etiology. A whole-body scan with 123 I detected a pelvic hyperfixation suggesting struma ovarii, and a thyroid differentiated left ovarian teratoma 3 cm in size was surgically removed. We screened for mutations of thyroid-stimulating hormone receptor and Gs-a protein genes, as these mutations are common in thyroid adenomas. We did not identify any mutations. Androgen receptor study demonstrated a monoclonal status. Comparative genomic hybridization did not reveal any chromosomal abnormality. However, loss of heterozygosity analysis showed several structural abnormalities, compared with the majority of benign ovarian teratomas, which show a normal karyotype. Conclusions: This is the first well-documented report of thyrotoxic struma ovarii revealed after treatment of a single thyroid toxic adenoma. We have shown in this case that struma ovarii originates from a single germ cell, and, albeit benign, this tumor presents several chromosomal abnormalities. Struma ovarii-induced hyperthyroidism is likely to be mediated by mechanisms different from those of the classical thyroid toxic adenoma.

Ectopic thyroid tissue: anatomical, clinical, and surgical implications of a rare entity

“…Malignant transformation is relatively uncommon, reported in about 15% of patients (44). Thyroid hyperfunction develops in 5-15% of patients (45,47). Struma ovariirelated thyrotoxicosis has been reported even after treatment of a thyroid toxic adenoma (45).…”

“…Thyroid hyperfunction develops in 5-15% of patients (45,47). Struma ovariirelated thyrotoxicosis has been reported even after treatment of a thyroid toxic adenoma (45). Papillary carcinoma has also been described either as an incidental finding (48) or with metastases to the lungs and pleura (49).…”

“…In all the above cases of subdiaphragmatic locations of thyroid gland, either aberrant migration or heterotopic differentiation of uncommitted endodermal cells could be hypothesized (7). Orthotopic thyroid gland usually coexists (45,48,58). In any case, the possibility of a metastatic origin for the ectopic follicles from an occult thyroid carcinoma should always be excluded.…”

Follicular Variant of Papillary Thyroid Carcinoma Arising in a Mature Cystic Teratoma of the Ovary

“…In literature, most of the data about this condition is collected from individual case reports, case series [1,2,4]. As presented in this case, the majority of cases are incidentally diagnosed [5,[6][7][8][9]. Malignant struma ovarii often occurs in the fi fth decade of life [3].…”

“…There is no gold standard and direct comparisons between treatment approaches. Following surgical staging, some authors recommend thyroidectomy and I 131 radioablation [4,9].…”