OBJECTIVES:: Lymphangiomas are relatively uncommon lesions of the lymphatic channels that can arise in virtually any part of the body provided by lymphatic vessels. The most common localization is the head/neck region, with only sporadic reports in other sites. The mediastinum is a rare location, with around 20 cases reported in the literature. METHODS:: We describe one case of mediastinal lymphangioma with a true intrathymic localization, which to our knowledge has never been described. RESULTS:: The gross features and microscopic findings are reported with a discussion of the clinicopathologic signatures of this pathologic entity. CONCLUSIONS:: Intrathymic lymphangioma should always be taken into consideration in the differential diagnosis of cystic mediastinal lesions in children and adult patients.