# Massive Thymic Hyperplasia in Graves Disease

## TL;DR

A rare case of a large thymic mass in a patient with Graves disease is reported, which regressed with treatment, highlighting the importance of recognizing this association.

## Contribution

This case report adds to the literature by describing an unusually large thymic hyperplasia in Graves disease without severe thyrotoxicosis.

## Key findings

- A 70 mm × 21 mm × 121 mm thymic mass was observed in a patient with newly diagnosed Graves disease.
- The mass regressed with antithyroid medication, supporting a diagnosis of thymic hyperplasia.
- The case emphasizes the need to consider thymic hyperplasia in Graves disease to avoid unnecessary interventions.

## Abstract

Thymic hyperplasia (TH) is a rare but established complication of Graves disease (GD). It is a benign phenomenon that regresses with appropriate treatment of GD. We report the case of a Burmese refugee with newly diagnosed GD, who had an incidental thymic mass measuring 70 mm × 21 mm × 121 mm. The size of the mass exceeded typical reports in the literature but was not accompanied by a substantial thyrotoxicosis. As the mass receded with antithyroid medication, a presumptive diagnosis of TH was ultimately made. Recognition of this association is vital to prevent unnecessary biopsy and surgical intervention.