Primary rhabdomyosarcoma of the thyroid in an adult with auricular thrombosis.

INTRODUCTION: Rhabdomyoscarcoma (RMS) is the most common soft-part tumour in children, however, it is infrequent in adults. Thyroid involvement is exceptional and only four cases have been reported: two primary RMS in children and another two cases in young adults with RMS metastasis to the thyroid. We report the first case in the literature of a primary adult RMS with thyroid involvement and superior vena cava syndrome.

CASE PRESENTATION: A 67-year-old male was admitted for an oedema of the arm extending to the laterocervical region. Computed tomography showed a 6cm mass in the hemithyroid with venous thrombosis to the auricle. Fine-needle aspiration was compatible with Bethesda category III. Surgery revealed a stone-hard consistency thyroid. An intraoperative biopsy showed an undifferentiated neoplasia, and no additional surgical intervention was undertaken. The patient died 48hours later. Definitive histology showed a RMS.

DISCUSSION: Venous thrombosis due to a thyroid tumour is infrequent. The scarce information in the literature recommends that thyroid carcinomas with auricular thrombosis be resected as soon as they are diagnosed. However, in cases of anaplastic or poorly differentiated carcinomas is controversial. Had there been a preoperative diagnosis in the histology in our case, surgery would not have been indicated.