[A surgically treated case of capsulated thymoma with thymic cyst]

A 56-year-old woman was pointed out an abnormal shadow on chest roentgenogram. Chest CT and MRI showed a solid mass with a cyst at right anterior mediastinum. Clinical diagnosis was thymoma with cyst, and surgical excision was performed. The histopathological examination of the resected specimen demonstrated that the epithelia of the cyst wall was single cuboidal or squamous cells and contained some foci of thymic tissue. The solid mass was capsulated and predominantly composed of lymphocytes. The pathological diagnosis was a thymoma (predominantly lymphocytic type) with thymic cyst. She is doing well for 10 years postoperatively.