Primary carcinomas of the thymus are rare. A variety of histologic patterns have been reported, and the most common are squamous cell carcinoma, lymphoepithelioma-like carcinoma, and basaloid carcinoma. Adenocarcinomas of the thymus are extremely rare. As determined from a literature search, a pure tubular adenocarcinoma has never been previously described, and thus, this is first case report of tubular adenocarcinoma of the thymus. A combined resection of the superior vena cava and pencardium was performed. Immunohistochemically, the tumor cells were positive for CD5. [ABSTRACT FROM AUTHOR]