Unusual primary tumors presenting as papillary carcinomas metastatic to the neck.

The presence of a metastatic papillary carcinoma in the neck is presumptive evidence of a primary thyroid neoplasm since neck metastases of other primary tumors are uncommon. Immunohistochemical studies may be required to diagnose these metastases. We report 2 cases in which an unrelated tumor mimicked a thyroid malignancy. Both patients had been referred for evaluation of enlarged lymph neck nodes without any other symptoms. In both cases, a lymph node biopsy identified a metastatic papillary adenocarcinoma that was believed to be consistent with a thyroid primary. Thyroidectomy was not performed in either case. Further investigations led to the diagnosis of other primary tumors that were unrelated to the thyroid; the unrelated primaries were an ovarian serous tumor in one patient and a papillary renal cell carcinoma in the other.