Metastatic parotid tumor: A rare presentation for papillary carcinoma of thyroid

Differentiated thyroid carcinomas usually present with a thyroid swelling with or without regional lymph node involvement. The purpose of this case study is to demonstrate a rare clinical presentation of papillary carcinoma of thyroid. A 70-year-old female presented with right parotid swelling of 3 years duration. She was evaluated and a primary parotid neoplasm was suspected. Thereafter, she was subjected to superficial parotidectomy. Histopathology of the specimen revealed a metastasis of a follicular variant of papillary carcinoma of the thyroid. Ultrasonography of the neck revealed a hypoechoic area in the left lobe of the thyroid. Her serum thyroglobulin was >800 ng/mL. A near total thyroidectomy was performed and histopathology of the specimen revealed a follicular variant (diffuse subtype) of papillary carcinoma of the thyroid. Right parotid swelling recurred following surgery. In addition the patient developed right chest wall and left scapular swelling. Serum thyroglobulin remained >800 ng/mL. She was administered 250 mCi of I-131 orally following diagnostic studies. A whole body PET scan was also performed 60 minutes after the intravenous injection of 370 MBq (10 mCi) of F-18 FDG. Her post-therapy scan showed avid I-131 uptake in the right parotid swelling, left scapular region, D9, L1 vertebrae, right chest region, and minimal uptake in the thyroid bed. F-18 FDG PET scan showed enhanced metabolic activity in the known metastatic sites. The occurrence of parotid metastases from a primary in the thyroid is an exception rather than rule. The aggressive nature of the diffuse follicular variant of papillary carcinoma of the thyroid in conjunction with avid F-18 FDG uptake in metastases may explain the spread to unusual sites as demonstrated in the present case.