A Case of Solitary Thyroid Myofibroma in a Child

Abstract

An 8-year-old boy presented with a mass on the left side of the anterior neck. The mass (27 × 19 × 24 mm) was detected in the left lobe of the thyroid gland by ultrasonography and enhanced as multiple nodules by CT scan. Laboratory examinations showed a tumor marker, and thyroid hormone levels were within the normal range. Fine needle aspiration cytological diagnosis showed a class III tumor. After extirpation of the tumor, medullary thyroid cancer was suspected from the frozen section report. Therefore, we performed left lobectomy and ipsilateral lymph node dissection. However, the final diagnosis was myofibroma. Myofibroma is a rare benign mesenchymal disorder characterized by the formation of tumors in the skin, subcutaneous tissue, muscle, bone, and viscera. To the best of our knowledge, this is the first reported case in Japan and the second in the world. We experienced treating a case of resected solitary thyroid myofibroma in a child. It is difficult to differentiate between solitary thyroid myofibroma and other thyroid tumors, such as adenomatous goiter or malignant tumor, and special attention is required during the management of this type of thyroid tumor.