title: Papillary thyroid carcinoma mistaken for malignant melanoma: pitfalls in diagnosis.
abstract: BACKGROUND
  Immunohistochemical methods and aspiration cytology are used with increasing frequency in the diagnosis of head and neck histopathology. Magnetic resonance imaging is also gaining popularity as a diagnostic tool.
  
  
  METHODS
  We report a case of papillary thyroid carcinoma which was initially misdiagnosed as malignant melanoma due to several confounding diagnostic test results.
  
  
  RESULTS
  False-positive immunostaining of a cytologic preparation with a commercial preparation of HMB45 melanoma stain and characteristic MRI findings contributed to the erroneous diagnosis of malignant melanoma.
  
  
  CONCLUSIONS
  Potential pitfalls in test interpretation are discussed, and recommendations for the judicious use of immunostaining, MRI, and other diagnostic studies are presented.
authors.affiliation: Department of Otolaryngology/Head and Neck Surgery, University of Washington School of Medicine, Seattle, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Orloff
authors.forename: E A
authors.initials: EA
authors.lastname: Weymuller
authors.forename: M J
authors.initials: MJ
authors.lastname: Flaherty
mesh_terms: D000293:Adolescent; D000951:Antigens, Neoplasm / Q000032:analysis; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000276:immunology / Q000601:surgery; D003951:Diagnostic Errors; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D008545:Melanoma / Q000175:diagnosis* / Q000276:immunology; D058950:Melanoma-Specific Antigens; D009333:Neck; D009363:Neoplasm Proteins / Q000032:analysis; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000276:immunology / Q000601:surgery
chemical_list: D000951:Antigens, Neoplasm; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins