# Hepatic Cyst Radioiodine Uptake on Whole-Body Scan in Differentiated Thyroid Cancer: Implications for Lesion Characterization and Misdiagnosis Avoidance

## TL;DR

A case report shows how a liver lesion seen on a thyroid cancer scan can be misdiagnosed, highlighting the need for careful interpretation.

## Contribution

Highlights a rare case of hepatic cyst and arteriovenous malformation mimicking thyroid cancer metastasis on RAI scans.

## Key findings

- A hepatic cyst and arteriovenous malformation were identified in a thyroid cancer patient via RAI scan and MRI.
- These findings could be mistaken for metastatic thyroid cancer or other liver pathologies.
- Recognizing such patterns can prevent misdiagnosis and improve diagnostic accuracy in thyroid cancer management.

## Abstract

Radioactive iodine (RAI) imaging constitutes a fundamental diagnostic tool in post-operative thyroid cancer management. A diverse spectrum of uptake patterns, encompassing both physiological and pathological entities, has been reported in patients undergoing RAI studies. Particularly, a variety of non-thyroidal conditions can present with unusual patterns of RAI uptake in the liver, complicating diagnosis. This case report presents a 51-year-old female with papillary thyroid cancer who underwent a whole-body RAI scan. The study revealed an atypical pattern of increased radiotracer concentration within the liver for which subsequent radiological investigations led to the diagnosis of two liver lesions, one was a simple hepatic cyst and another was most likely to be a hepatic arteriovenous malformation (HAVM) both located in segment VII based on abdominal magnetic resonance imaging (MRI) findings, an unexpected finding that could be mistaken for other differential diagnoses, including metastatic differentiated thyroid cancer (DTC), granulomas, abscesses, hydatid cysts, biliary tract dilatation, and other benign non-thyroidal neoplasia. Recognizing these diverse entities is essential for the accurate interpretation of RAI scans and for avoiding misdiagnosis. This finding may help clinicians avoid misdiagnosing such ancillary observations as metastases, thereby improving diagnostic accuracy in thyroid cancer management.