Ectopic Pelvic Kidney Mimicking Sacral Metastasis on Post-Therapy Iodine-131 Scan of a Thyroid Cancer Patient

Radioiodine whole body scan pitfalls in differentiated thyroid cancer

PURPOSE

whole body scan (WBS) performed following diagnostic or therapeutic administration of I-131 is useful in patients with differentiated thyroid carcinoma. However, it can be falsely positive in various circumstances. We aimed to report a series of pitfalls in a clinical perspective.

METHODS

A search in the database PubMed utilizing the following terms: "false radioiodine uptake" and "false positive iodine 131 scan" has been made in January 2023. Among the 346 studies screened, 230 were included in this review, with a total of 370 cases collected. Physiological uptakes were excluded. For each patient, sex, age, dose of I-131 administered, region and specific organ of uptake and cause of false uptake were evaluated.

RESULTS

370 cases of false radioiodine uptake were reported, 19.1% in the head-neck region, 34.2% in the chest, 14.8% in the abdomen, 20.8% in the pelvis, and 11.1% in the soft tissues and skeletal system. The origin of false radioiodine uptake was referred to non-tumoral diseases in 205/370 cases (55.1%), benign tumors in 108/370 cases (29.5%), malignant tumors in 25/370 cases (6.7%), and other causes in 32/370 cases (8.7%).

CONCLUSIONS

WBS is useful in the follow-up of patients with differentiated thyroid carcinoma, however it can be falsely positive in various circumstances. For this reason, it is critically important to correlate the scintigraphic result with patient's medical history, serum thyroglobulin levels, additional imaging studies and cytologic and/or histologic result.

Bilateral subdiaphragmatic renal ectopia with associated congenital anomalies: a case report and systematic review of cases

Background

Cephalad renal ectopia is rare. Ectopic kidneys besides being prone to various pathologies are occasionally associated with other congenital abnormalities. To the best our knowledge, at the time of this writing, only ten cases of bilateral subdiaphragmatic renal ectopia had been reported.

Case presentation: We present a rare case of bilateral subdiaphragmatic ectopic kidneys incidentally discovered during evaluation of the abdominal pain. In addition, our patient had associated anomalies of the liver, spleen and mesocardia.

Conclusions

Recognition of this condition is important for accurate diagnosis, surgical and/or intervention planning, as well as identifying other associated anomalies.

Variable 131I Activity in Renal Stone in a Patient With Thyroid Cancer

ABSTRACT

A 42-year-old woman underwent 131I radiotherapy for thyroid papillary cancer. A focal elevated 131I activity in the right kidney was revealed on the initial whole-body posttherapeutic images, which was located in the region of a renal stone. However, on the follow-up 131I images acquired 6 months later, there was no longer any increased activity in the region of this stone, which had moved into right ureter. Our case indicates that the 131I activity accumulated in the region of urinary stone is due to stagnated radioactive urine rather than due to the stone per se.