A Unique Case of Intranasal Metastasis from Occult Poorly Differentiated Thyroid Carcinoma

Poorly differentiated thyroid carcinomas (PDTCs) lie, both morphologically and behaviorally, between well-differentiated and undifferentiated carcinomas. Metastasis of poorly differentiated thyroid carcinoma to the intranasal cavity has not been reported previously in the literature.

A 48-year-old male patient presented with massive epistaxis and nasal obstruction. On nasal examination, a bleeding, vascular mass was seen filling the left nasal cavity. The histopathological report of the nasal mass was well-differentiated thyroid carcinoma metastasis. Whole body scintigraphy, ultrasonography and positron emission tomography were done to rule out other possible metastases in the body and determine the origin of the tumor, which was identified as the left lobe of the thyroid gland, and there were multiple metastases involving the lung, sacroiliac area, and left humerus. Histopathological examination of a thyroidectomy specimen revealed PDTC consisting of insular, follicular, and papillary components. Postoperatively, the patient received radioactive iodine ablation therapy (iodine-131) and a course of external beam radiation therapy to the sacroiliac area and other metastatic regions. No recurrences were observed in a follow-up period of 5 years after surgery.

The metastasis of differentiated thyroid carcinoma as a component of PDTC to the intranasal cavity has not been reported before. It is interesting that the well-differentiated component of the tumor was metastasized in our patient. Due to the aggressiveness of PDTC and the poor survival rates in patients who undergo surgery alone, a multidisciplinary treatment approach is required.