Cutaneous metastasis of medullary thyroid carcinoma as the initial manifestation of an otherwise limited malignancy: a case report.

Cutaneous metastasis from a thyroid carcinoma, particularly medullary thyroid carcinoma (MTC), are rare. Herein, we report the first case of MTC in which metastatic lesions, were also the earliest sign of the disease, affecting the skin. This is as well the third reported case of undetected MTC initially manifested by metastatic skin lesions. A 79-year-old white woman presented with painful skin lesions. The lesions were biopsied. Based on routine light microscopic examination and immunohistochemical study, MTC was the most likely diagnosis. Subsequent investigations identified the primary thyroid tumor, which also proved to be MTC. No other metastatic lesion could be demonstrated by further evaluations. This report illustrates a novel presentation of MTC. MTC metastases should be considered in the differential diagnosis of cutaneous lesions. It is important to histopathologically examine the lesions and perform appropriate immunohistochemical study that must include calcitonin and other neuroendocrine markers.