Unusual uptake of ¹³¹iodine in bilateral ovarian endometriosis cysts in a patient with thyroid cancer

Excerpt

A 22-year-old woman with a history of differentiated thyroid cancer (DTC) previously treated with total thyroidectomy 1 month ago (histological subtype: papillary thyroid carcinoma; tumor size 2.8×2.2×1.5cm; cT₂N₀M₀, pT₂N_1bM₀, stage I, 8th Edition AJCC TNM Staging). The serum levels of thyroglobulin 1.57ng/ml (reference range, 3.5-77) and T₃1.70pg/ml (1.8-3.8) were decreased while thyroid-stimulating hormone 3.309mIU/l (0.38–5.57) and T₄1.08ng/dl (0.78–1.86) were in the normal range. The maximum percent uptake of ¹³¹iodine (¹³¹I) was 3%. Subsequently, the patient received 3.7GBq activity of ¹³¹I. We performed an ¹³¹I whole-body scan for this patient 3 days after ablation therapy (Siemens; Symbia T16; 16-slice CT, 120 mA, 130 kV; 10 cm/min; 64 × 64 matrix). The images (Fig. 1) of ¹³¹I whole-body scan showed a focal radioiodine accumulation in the region of right pelvic cavity, which corresponded to a cystic mass (~4.5 cm in size) with heterogeneous liquid density on the subsequent SPECT/CT images. In addition, there was a cystic mass (~8.5 cm in size) anterior to the uterus with homogeneous liquid density on the fusion images (the mean Hounsfield unit of 15), which had extremely mild ¹³¹I activity. Detailed history asking revealed that she had dysmenorrhea for 8 years and aggravated for 1 year. Physical examination showed local abdominal tenderness. The findings were suggestive of bilateral ovarian endometriosis cysts. Surgery was performed and the lesions were resected. The pathological examination confirmed the lesions were in keeping with bilateral ovarian endometriosis cysts.

…