An unusual thyroid tumor in a child.

Malignant neoplasms of the thyroid gland are quite rare in children. Winship, in his classic article, could find only 562 cases in the literature. The histopathological patterns resemble those of the adult tumors. Despite early cervical metastasis, the prognosis in general is favorable, with many long-term survivals. Prior exposure to radiation of the head and neck is a definite pre-disposing factor. Teratomas of the neck are a medical curiosity--less than 100 cases are described in the literature. The vast majority of these are found during the neonatal period, and are benign histologically. These are usually large, cystic, bulky masses which produce mechanical obstruction of the upper airway and digestive tract. Only one of these tumors, described by Pupovac in 1896, has been considered malignant. A six-year-old child was examined with a right thyroid mass of three months' duration. The thyroid scan showed a "cold nodule." At surgery, a well-encapsulated mass was found. The pathology showed a predominance of malignant spindle cells, with areas of papillary carcinoma; however, there were well-defined mucous glands present in the tumor. Clinically the child has remained well and asymptomatic. The slides have been extensively reviewed. To my knowledge no such tumor has been previously described. The tumor is considered to be a malignant thyroid tumor growing out of teratomatous tissue.