title: An unusual combined thymic carcinoma composed of squamous cell carcinoma and type AB thymoma: a rare case report.
abstract: BACKGROUND
  Combined thymic carcinoma is a malignant neoplasm of the thymus recently added to the 4th edition of the World Health Organization (WHO) classification of tumors of the lung, pleura, thymus and heart. It involves at least one type of thymic carcinoma and another thymic epithelial tumor. The previously used term "combined thymic epithelial tumor" has been abandoned.
  
  
  METHODS
  Here, we present an unusual case of combined thymic carcinoma of the thymus in a 44-year-old male who had suffered from fever, chest pain, chest tightness and shortness of breath. Magnetic resonance imaging (MRI) detected a mass approximately 6.4 cm × 4.2 cm in the anterior mediastinum, and a nonencapsulated tumor approximately 5.0 cm × 3.5 cm × 2.5 cm with an irregular shape was resected. The morphological features and the immunostaining pattern of the tumor revealed it to be an unusual combined thymic carcinoma consisting of type AB thymoma and squamous cell carcinoma. There were cysts of various sizes, some of which had crack-like structures, in the type AB thymoma area. A gradual transition could be seen between these structures and the squamous cell carcinoma, indicating that the carcinoma portion may have originated from the composition of the thymoma.
  
  
  CONCLUSIONS
  Combined thymic carcinoma composed of type AB thymoma and squamous cell carcinoma is rare, and the carcinoma portion may have originated from epithelial structures in the type AB thymoma.
authors.affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences of China Medical University, 110001, Shenyang, China.|97K Seven-year Program of Medicine, China Medical University, 110001, Shenyang, China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences of China Medical University, 110001, Shenyang, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences of China Medical University, 110001, Shenyang, China.
authors.forename: Xiuying
authors.initials: X
authors.lastname: Shi
authors.affiliation: Department of Breast Surgery, Department of Surgical Oncology, Research Unit of General Surgery, the First Affiliated Hospital of China Medical University, 110001, Shenyang, China.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Mao
authors.affiliation: Department of Hepatobiliary and Spleenary Surgery, The Affiliated Shengjing Hospital, China Medical University, 110004, Shenyang, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences of China Medical University, 110001, Shenyang, China. cffan@cmu.edu.cn.
authors.forename: Chuifeng
authors.initials: C
authors.lastname: Fan
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009375:Neoplasms, Glandular and Epithelial / Q000473:pathology*; D013953:Thymus Neoplasms / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor
keywords: Combined thymic carcinoma; Mediastinum; Squamous cell carcinoma; Type AB thymoma