title: Concomitant pulmonary and thyroid tumors identified by FDG PET/CT and immunohistochemical techniques.
abstract: BACKGROUND
  The exact diagnosis of double primary papillary adenocarcinoma of thyroid and lung is even rarer, to our knowledge no report in the literature by [¹⁸F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography/X-ray CT(FDG PET/CT) with surgical specimens immunohistochemistry(IHC). We report a patient with abnormal FDG PET/CT in thyroid and lung, this unusual presentation may lead to misdiagnosis without surgical specimens IHC.
  
  
  METHODS
  A 56-year-old man with coughing three months. FDG PET/CT was performed, and resection specimens of lung and thyroid were detected by hematoxylin eosin staining (HE) and IHC. PET/CT: lung tumor SUVmax: 3.69, delay: 5.17; and thyroid tumor SUVmax 19.97. HE reveal papillary adenocarcinoma, but histological differentiation of primary pulmonary adenocarcinoma from metastatic adenocarcinoma is sometimes difficult because of their phenotypic similarities. So IHC was performed, the IHC of lung tumor: cytokeratin 20 (CK20)⁻, thyroglobulin(Tg)⁻, cytokeratin7(CK7)+, thyroid transcription factor-1 (TTF-1)+; thyroid tumor: CK7+, TTF-1+, thyroglobulin+, CK20⁻. Therefore, the final diagnosis was double primary adenocarcinomas of thyroid and lung.
  
  
  CONCLUSIONS
  FDG PET/CT has preliminary diagnostic capacity of multiple primary tumors; the final diagnosis should be adopted for specimens after tumor-specific markers IHC to obtain. Consequently, effective therapeutic approaches can be designed and conducted.
authors.affiliation: Liaoning Laboratory of Cancer Genomics and Department of Cell Biology, Dalian Medical University, Dalian, China.
authors.forename: Guangwen
authors.initials: G
authors.lastname: Zhu
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yaming
authors.initials: Y
authors.lastname: Li
authors.forename: Shujun
authors.initials: S
authors.lastname: Liang
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
mesh_terms: D000231:Adenocarcinoma, Papillary / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007124:Immunoenzyme Techniques; D008175:Lung Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000175:diagnosis* / Q000628:therapy; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18