Pitfall of I-131 whole body scan: a mucinous adenocarcinoma of the ovary

Abstract

False positive radioiodine uptake following thyroidectomy for differentiated thyroid cancer has been reported in some cases. A 57-year-old female patient was referred for ablative radioiodine treatment four weeks after undergoing total thyroidectomy for papillary thyroid carcinoma. Posttherapeutic I-131 scintigraphy showed uptake in the neck and large focus in the lower abdomen and pelvis. Pathology revealed a mucinous adenocarcinoma of the right ovary.

False-positive radioiodine uptake after radioiodine treatment in differentiated thyroid cancer

“…Overall, the literature showed 145 case reports and two series regarding false-positive 131 uptake after RIT For the reasons stated above, we excluded 129 papers, considering only those in which SPECT/CT was performed. A total of 18 papers were thus included: 1 series [17] and 17 case reports [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The series reported 23 cases of falsepositive results: 15 in the chest, six in the pelvis, one in the cranium, and one in the abdomen.…”

“…Overall, 20 cases regarded radioiodine uptake in the chest: 11 in the lung (mainly inflammatory), four on the chest bones or on soft tissue due to inflammation/trauma, one in the thymus, one mesenchymal tumor and the rest in not well-characterized sites [17][18][19][20][21]34]. A total of 15 cases regarded uptake in the abdomen/pelvis: six in the kidney (cysts), five in the ovary (teratoma, benign cysts and malignant disease), two in the uterus and the others in not well-characterized sites [22][23][24][25][26][27][28][29]. Three cases reported uptake in the head: two surgical clips, and one on one eye [30,31,33].…”

“…Three cases reported uptake in the head: two surgical clips, and one on one eye [30,31,33]. A few other cases were in other sites [24,32]. In many cases, accumulation of radioiodine and the cause was simply classified as "undetermined".…”

“…However in all cases, diagnosis was possible by SPECT/CT and other imaging techniques. In four cases [17,[22][23][24], all were in the pelvis, diagnosis was virtually impossible, and surgery had to be performed to clarify the histology. Table 1 reports the possible causes of false-positive imaging, possible sites in SPECT/CT, and possible actions for reaching a diagnosis.…”

Orbital Radioiodine Uptake in Epithelial Conjunctival Inclusion Cyst on Scintigraphy in a Patient With Differentiated Thyroid Cancer

“…11 In case of a cyst containing mucus, this process could take longer as reported in some cases of ovarian mucinous tumors accumulating 131 I. 15,16…”