Thymolipoma. A report of nine cases, with emphasis on its association with myasthenia gravis

Thymolipomas are rare tumors of the anterior mediastinum accounting for up to 9% of all thymic tumors. These tumors are associated with autoimmune diseases in up to 50% of the patients, including myasthenia gravis, aplastic anemia, hypogammaglobulinemia, lichen planus, and Graves' disease. These tumors with a fatty appearance also can arise in older patients with autoimmune disease.

This retrospective study evaluated the thymolipomas from nine patients at a single institution, which were resected between 2002 and 2007. The clinical data as well as radiologic findings were evaluated, together with the follow-up.

Seven patients initially presented with myasthenia gravis, and therefore they underwent a resection of the thymus, even though imaging techniques did not reveal a tumor in any of the cases. Another patient showed no symptoms of autoimmune disease for 20 years, and though cardiomegaly was suspected, further investigation revealed a thymolipoma. The symptoms of myasthenia gravis improved following the surgery in one patient. During follow-up, one patient died due to esophageal cancer, and the remaining patients are alive without recurrence.

Thymolipomas are benign tumors that show an excellent outcome. Patients with autoimmune disease symptoms occasionally show an improvement of the symptoms after a resection of the tumors.