Papillary thyroid carcinoma mistaken for malignant melanoma: pitfalls in diagnosis.
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.
Orloff
L A
LA
Department of Otolaryngology/Head and Neck Surgery, University of Washington School of Medicine, Seattle, USA.
Weymuller
E A
EA
Flaherty
M J
MJ
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
D000951:Antigens, Neoplasm; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins