Incidental finding of ovarian teratoma on post-therapy scan for papillary thyroid cancer and impact of SPECT/CT imaging

Abstract

A 41-year old woman post thyroidectomy and neck dissection is presented in this case. She initially presented goiter and an enlarged cervical lymph node. She had no family history of cancer or radiation therapy. She had total thyroidectomy and found to have papillary thyroid cancer (T4N1M0). Histopathology report revealed multifocal classical papillary thyroid carcinoma with lympho-vascular invasion, extra-thyroidal extension, and positive lymph nodes. She was treated with 6.5 Gigabecquerel (GBq) of 131Iodine. Whole-body scan showed uptake in the neck and large focus in the left lower abdomen. Single-photon emission computed tomography SPECT/CT demonstrated a round shaped mass in the left pelvis. Pathology revealed cystic teratoma with benign thyroid tissue (struma ovarii), and no malignancy. Two months later, she had the second treatment with 5.5 GBq 131Iodine. Her follow-up stimulated and non-stimulated thyroglobulin levels were significantly lower, and there was no abnormal uptake in the follow-up scan.

Endocrine Scintigraphy with Hybrid SPECT/CT

“…While these variants are usually recognized on planar imaging, SPECT/CT resolves diagnostic uncertainty with greater confidence and improved accuracy (120,121). Numerous case reports have demonstrated the utility of SPECT/CT for confirmation of benign "mimics" of disease; eg, blocked nasolacrimal duct, lingual thyroid, thymus, struma ovarii, ovarian teratoma, menstruating uterus, and radioiodine accumulation in simple renal cysts (93,(102)(103)(104)(105)(106)(107)(108)(109)(110)(122)(123)(124)(125)(126).…”

Incidental Findings of Intense Radioiodine Uptake in Struma Ovarii and Bilateral Nonlactating Breasts Simultaneously on Postablation 131I SPECT/CT for Papillary Thyroid Cancer

“…One of these reports concerned a benign functioning struma ovarii with hyperthyroidism, provisionally diagnosed by clinical and radiologic findings and confirmed on total hysterectomy and bilateral salpingo-oophorectomy [1]. There are two reports of nonfunctioning struma ovaries diagnosed incidentally after iodine therapy for which oophorectomy was performed immediately [2,3]. A very rare case was reported of cystic ovarian metastasis from papillary thyroid cancer that was diagnosed on a post-therapy whole-body scan with increasing thyroglobulin, and also confirmed on pelvic surgery [4].…”

Abnormal radioiodine uptake on post-therapy whole body scan and sodium/iodine symporter expression in a dermoid cyst of the ovary: report of a case and review of the literature

“…As shown in the literature (18), up to 20% of ovarian teratomas contain thyroid tissue, and 5% of them are struma ovarii, defined as the tumour being more than half thyroid tissue (18,19). Struma ovarii represent an uncommon but well known false-positive localization of 131 I (20)(21)(22), because it is mainly or exclusively composed of well-differentiated and functioning thyroid tissue, able to trap iodine as well as to produce thyroid hormones and thyroglobylin (18)(19)(20)(21)(22). Up to date, there are only four reports in the literature of radioiodine uptake by ovarian dermoid cysts, not be classified as struma ovarii (23)(24)(25)(26).…”