Epidemiology: Carcinoids of thymus can occur as sporadic tumors, may be associated with carcinoid tumors of other locations such as ileum and bronchus, or occur as a component of multiple endocrine neoplasia (MEN) 1 or 2a. About 25% of thymic carcinoid cases have family history of MEN1. Conversely, about 8% of MEN1 patients have thymic carcinoids. Rare cases have occurred in patients with Neurofibromatosis type 1. The image shows a uniform population of polygonal tumor cells with small round regular nuclei, finely granular chromatin and eosinophilic cytoplasm. There is a delicate vascular stroma between the cells nests and trabeculae.