PAPILLARY THYROID-CARCINOMA MISTAKEN FOR MALIGNANT-MELANOMA - PITFALLS IN DIAGNOSIS

Background. Immunohistochemical methods and aspiration cytology are us ed with increasing frequency in the diagnosis of head and neck histopa thology. Magnetic resonance imaging is also gaining popularity as a di agnostic tool. Methods. We report a case of papillary thyroid carcinom a which was initially misdiagnosed as malignant melanoma due to severa l confounding diagnostic test results. Results. False-positive immunos taining of a cytologic preparation with a commercial preparation of HM B45 melanoma stain and characteristic MRI findings contributed to the erroneous diagnosis of malignant melanoma. Conclusions. Potential pitf alls in test interpretation are discussed, and recommendations for the judicious use of immunostaining, MRI, and other diagnostic studies ar e presented. (C) 1995 John Wiley and Sons, Inc.