Hidden in plain site: Papillary thyroid carcinoma with metastases to branchial cleft cyst

Abstract

30-year-old female with a history of papillary thyroid carcinoma, status post thyroidectomy and radioactive iodine ablation presented for a routine follow up visit for management of hypothyroidism. Patient was noted to have a congenital branchial cleft cyst in the right superolateral cervical area (Figure 1). Total body scan conducted following ablative I131 dose, 150 mCi had demonstrated no uptake throughout the body including branchial cyst indicative of metastasis. Elevated thyroglobulin tumor marker (14 ng/mL) at this visit was attributed to production by residual thyroid tissue. However, the level continued to rise over the next year to 42 ng/ml. Thyroid ultrasound failed to demonstrate any residual thyroid tissue. Total body scan with I123 scan revealed no uptake anywhere in the body. She also revealed that she has experienced some difficulty swallowing. Repeat thyroid ultrasound noted increase in size of a congenital submandibular branchial cleft cyst with increased vascularity. Therefore, ultrasound guided core needle biopsy of the enlarging right neck mass was performed. Pathology report of the previously known benign branchial cleft cyst showed presence of thyroid epithelium arranged in delicate papillary structures (Figure 2A and 2B). Patient underwent a branchial cyst excision and cervical lymph node dissection.