title: Clinicopathological analysis of 21 thymic neuroendocrine tumors.
abstract: BACKGROUND
  Thymic neuroendocrine carcinomas (NECs) are uncommon, for which there is no established information available because of a limited number of epidemiological study in Asia.
  
  
  METHODS
  We reviewed 21 cases of surgically resected thymic NECs, and evaluated their pathological and clinical features.
  
  
  RESULTS
  It showed male predominance (male/female ratio, 15/6) with wide age range from 20 to 72 years (mean age, 49 years). All 21 cases were divided into two types according to the World Health Organization criteria: atypical carcinoid (n=18) and large cell NEC (n=3). Three cases of atypical carcinoid (AC) were associated with ectopic Cushing's syndrome. All the patients (3/3) with large cell NEC (3/3) and 16.7% (3/18) of those with AC died of tumor progression. Common sites of metastasis included lung, lymph node, brain, lumbar spine, mediastinum, bone, and liver.
  
  
  CONCLUSIONS
  In conclusion, thymic neuroendocrine tumors carry a poor prognosis. Regarding the tumor classification, our results showed that a vast majority of carcinoids in the thymus correspond to ACs. In addition, our results also indicate that typical carcinoid is a very rare entity. Some cases of AC exhibited a large size, solid pattern and they showed aggressive clinical behavior, which highlights the spectrum of histologic appearances of thymic NECs.
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Soomin
authors.initials: S
authors.lastname: Ahn
authors.forename: Jae Jun
authors.initials: JJ
authors.lastname: Lee
authors.forename: Sang Yun
authors.initials: SY
authors.lastname: Ha
authors.forename: Chang Ohk
authors.initials: CO
authors.lastname: Sung
authors.forename: Jhingook
authors.initials: J
authors.lastname: Kim
authors.forename: Joungho
authors.initials: J
authors.lastname: Han
keywords: Carcinoid tumor; Carcinoma, neuroendocrine; Thymus gland