Metastatic Melanoma Mimicking a Papillary Carcinoma of the Thyroid in Fine Needle Aspiration Cytology: A Case Report / 대한세포병리학회지

ABSTRACT

Metastasis to the thyroid gland is very rare in clinical practice. We recently encountered a 65-year-old woman who presented with a large thyroid nodule that mimicked the cytologic features of a papillary thyroid carcinoma on fine needle aspiration biopsy (FNAB). Although initially diagnosed as a papillary thyroid carcinoma, a thorough clinical work-up revealed multiple lesions in the bones, liver, and nasal cavity, which were confirmed as metastases of a malignant melanoma. Despite a thorough physical examination, however, the primary skin lesion could not be identified. Although FNAB shows a high degree of accuracy in diagnosing primary thyroid tumors, it is less accurate in diagnosing metastases to the thyroid gland. A thorough clinical history with appropriate immunohistochemical staining assays is necessary for the accurate diagnosis of metastatic malignant melanoma.