A Rare False-Positive Whole-Body Scan in a Patient With Differentiated Thyroid Cancer: Unilateral Conjunctival...

Area of Science:

• Nuclear Medicine
• Oncology
• Ophthalmology

Background:

• Radioactive iodine (131 I) is a standard diagnostic and therapeutic agent for differentiated thyroid cancer (DTC).
• Whole-body scans using 131 I are sensitive for detecting thyroid tissue and metastases but lack specificity.
• False-positive findings on 131 I scans can complicate patient management by mimicking metastatic disease.

Purpose of the Study:

• To report a rare instance of false-positive radioactive iodine uptake in a patient with differentiated thyroid cancer.
• To highlight the potential for conjunctival concretions to cause misinterpretation on 131 I whole-body scans.
• To emphasize the importance of recognizing unusual causes of false-positive uptake in DTC management.

Main Methods:

• Case presentation of a patient with differentiated thyroid cancer undergoing 131 I whole-body scanning.
• Analysis of imaging findings to identify unexpected sites of radioactive iodine uptake.
• Histopathological examination or further investigation to determine the cause of false-positive uptake.

Main Results:

• A patient with DTC exhibited unexpected 131 I uptake on a whole-body scan.
• The uptake was identified as originating from conjunctival concretions, not metastatic DTC.
• This represents the first reported case of 131 I uptake by conjunctival concretions.

Conclusions:

• Conjunctival concretions can present as a rare cause of false-positive findings on 131 I whole-body scans in DTC patients.
• Careful evaluation and recognition of such benign conditions are crucial to avoid misdiagnosis of metastatic disease.
• This case underscores the need for comprehensive interpretation of 131 I scans, considering potential non-malignant sources of uptake.