# Acute Thyroid Swelling After Fine-Needle Aspiration in von Willebrand Disease: Case Report and Literature Review

## TL;DR

A patient with von Willebrand disease experienced temporary thyroid swelling after a fine-needle aspiration, which resolved quickly with no blood flow detected.

## Contribution

This case report highlights a rare complication of FNAC in bleeding disorders and suggests a new mechanism involving edema rather than hematoma.

## Key findings

- Thyroid swelling in a VWD patient after FNAC resolved within 12 hours with conservative treatment.
- Ultrasound showed hypoechoic areas without blood flow, indicating interstitial edema rather than a hematoma.
- Neuropeptide and histamine release may contribute to acute thyroid swelling after FNAC.

## Abstract

Fine-needle aspiration cytology (FNAC) can cause rare complications, including acute transient thyroid swelling (ATTS). We report a 71-year-old female with von Willebrand disease (VWD) who developed rapid thyroid enlargement post-FNAC. Ultrasonography showed hypoechoic areas without blood flow, suggesting interstitial edema rather than hematoma. The swelling resolved within 12 hours with conservative management. Neuropeptide and histamine release may contribute to this phenomenon. This case highlights the importance of coagulation assessment and monitoring in FNAC for bleeding disorders. Recognizing hypoechoic areas without blood flow on ultrasound (US) may aid in distinguishing edema from hematoma. Further studies are needed to clarify the mechanism.