[Diagnosis of metastasis of malignant melanoma in the thyroid gland with f18-FDG PET scan].

Metastases in the thyroid gland are very rare. When they occur, long-term survival is dismal; thus an early diagnosis is critical. Malignant melanoma is one of the tumors which may metastasize to the thyroid gland. Therefore we wanted to demonstrate F18-Fluorodeoxyglucose-Positron emission tomography (F18-FDG-PET) is a sensitive and reliable method to identify such metastases. We report about a 51-year-old man, who had an inguinal lymph node metastasis of a malignant melanoma with unknown primary tumor site. He came to us for an a follow-up F18-FDG-PET investigation. In the PET there was a pathologic FDG-uptake in the left lobe of the thyroid gland. The nodule was removed and showed a malignant melanoma metastasis. This unusual scenario underscores the value of the PET in the oncologic follow-up of patients with malignant melanoma.