Systemic follicular lymphoma in a patient with a history of thyroid eye disease: a case report.

The most common cause of both unilateral and bilateral proptosis in adults is thyroid eye disease (TED), and the diagnosis in typical cases is made without imaging. However, many other orbital diseases, including inflammatory, infectious, and neoplastic processes, can mimic the symptoms of thyroid eye disease, highlighting the importance of imaging and biopsy in challenging cases. There are limited reports in the literature of orbital lymphoma being diagnosed in patients with a history of thyroid eye disease. Here, we present the case of a patient with long-standing TED who developed new asymmetric proptosis and was subsequently diagnosed with systemic follicular lymphoma.