Thymic mucosa-associated lymphoid tissue lymphoma associated with bilateral orbital pseudotumor.

Mucosa-associated lymphoid tissue (MALT) lymphoma of the thymus is a rare condition, often characterized by its occurrence in a context of autoimmunity. We reported a first case of thymic MALT lymphoma following bilateral orbital pseudotumor. A 48-year-old man presented with bilateral exophthalmos diagnosed as orbital pseudotumor. His symptoms were relieved by an oral corticosteroid. Eleven years later, a mediastinal tumor was incidentally discovered. A thymectomy was performed, and histological examination revealed that the mass was a MALT lymphoma. There was no recurrence with no further treatment.