Abstract
We experienced an interesting case of mediastinal matured treatoma showing positive antibody titer to acetylcholine receptor which also presented difficulty in differential diagnosis from thymic tumor in imagings. A 31-year-old man was admitted to the hospital with a suspecion of mediastinal tumor found by chest roentogenogram. He had an anterior chest pain, general fatigue and fever but no clinical symptom of myasthenia gravis. Laboratory data showed liver dysfunction and positive antibody titer to acetylcholine receptor. Computed tomography and MRI revealed a heterogenous cystic lesion locating closely at the aortic arch and pulmonary artery. Under a diagnosis of thymic tumor, he underwent tumorectomy by longitudinal sternotomy. The tumor, measuring 9×6×5cm in size, had a thick capsule and contained internally red-brown fluid with pomade like jelly and a white solid mass with short hair. It was then histologically proven to be matured teratoma complicated by bleeding, which consisted of several components such as epithelium, glands, hair, cartilage and adipose tissue. Postoperative course was uneventful. Repeating biochemical examinations revealed the restored liver function and decreased antibody titer to acetylcholine receptor.
