Lymphoma is a common cause of proptosis in patients older than 50.

• A. True
• B. False
• C. Not sure
• D. Not applicable

Answer: (A)

In older patients, a new unilateral, painless proptosis is most often due to an orbital tumor, and lymphoma is the most common cause in this age group. Orbital lymphomas, especially extranodal marginal zone B-cell lymphomas (MALT type), are the leading primary orbital malignancies in adults and commonly present as slow-growing, painless proptosis with possible lacrimal gland involvement. Because imaging alone can’t distinguish lymphoma from other orbital processes, a biopsy is essential for a definitive diagnosis. While other conditions like thyroid eye disease can cause proptosis, they typically have different patterns (often bilateral and with prominent motility or lid findings) and occur with different systemic contexts, making lymphoma the most frequent culprit in patients over 50.