Inflammatory pseudotumor of the thymus.

A 44-year-old man with inflammatory pseudotumor of the thymus is reported. The patient was seen with fever, myalgia, and dyspnea and was found to have an anterior mediastinal mass and bilateral pleural effusions. The resected lesion consisted of a well-circumscribed mass of chronic inflammatory and fibrous tissue that virtually replaced the thymus. There was no morphological evidence of neoplasia. The patient's symptoms and roentgenographic abnormalities resolved with excision of most of the mass. To our knowledge, this report is the first instance of inflammatory pseudotumor of the thymus.