title: Metaplastic thymoma: report of an unusual thymic epithelial neoplasm arising in the wall of a thymic cyst.
abstract: In this report, a case of metaplastic thymoma arising in a thymic cyst wall is discussed. The patient was a 61-year-old male whose chief complaint was sweating and chest pain. Imaging study revealed a mediastinal mass with right hemithoracic extension. He underwent surgical resection of the mass and remnants of the thymus. Histologic studies showed a primary thymic neoplasm with a biphasic histologic pattern composed of 2 distinct epithelial and stromal components arising in a thymic cyst wall. Immunohistochemically, the epithelial component was cytokeratin positive and focally reactive for EMA. Marked expression of EMA and vimentin was seen in spindle cells. Metaplastic thymoma is an extremely rare variant of primary thymic epithelial neoplasms with only a few cases reported in the literature.
authors.affiliation: Department of Surgical Pathology, National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Science and Health Services, Tehran, Iran.
authors.forename: Mihan
authors.initials: M
authors.lastname: Poorabdollah
authors.forename: Ehsan
authors.initials: E
authors.lastname: Mehdizadeh
authors.forename: Foruzan
authors.initials: F
authors.lastname: Mohammadi
authors.forename: Shahram
authors.initials: S
authors.lastname: Sabeti
mesh_terms: D006801:Humans; D008297:Male; D008476:Mediastinal Cyst / Q000150:complications*; D008875:Middle Aged; D018396:Mucin-1 / Q000378:metabolism; D009375:Neoplasms, Glandular and Epithelial / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D013945:Thymoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D013953:Thymus Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D014746:Vimentin / Q000378:metabolism
chemical_list: D018396:Mucin-1; D014746:Vimentin