Melanocytic variant of medullary carcinoma or primary melanocytic thyroid neoplasia?

Malignant melanocytic thyroid neoplasm is a rare condition with around ten cases reported in the literature. We describe a case of a patient with thyroid nodule who underwent thyroidectomy by compressive effects. The anatomopathological diagnosis was pleomorphic malignant neoplasia, with evidences of component with melanocytic and neuroendocrine differentiation, with absolute predominance of the first one. Clinical follow-up showed no relapse after two years of follow-up, and calcitonin was low. This case demonstrates the difficulty in the diagnosis of this type of rare thyroid lesion, and especially, the great difficulty in the therapeutic conduct.