Occult Thyroid Carcinoma with Cervical Lymph Node Metastasis: A Rare Case Report.

Cervical lymph node metastasis is one of the most common clinical presentations of papillary thyroid carcinoma (PTC). Occult thyroid carcinoma is described as absence of primary tumour or with presence of microcarcinoma in thyroid with cervical lymph node metastasis. Frequency of occult thyroid cancer has decreased due to developments in imaging and improved accuracy of histological examinations. 38 year old male presented to us with complaints of swelling over the left side of neck for the past 2 months. Ultrasonography was suggestive of multiple suspicious enlarged nodes in left level II, III, IV and V and fine needle aspiration cytology showed features of metastatic PTC. He was planned for total thyroidectomy with central compartment clearance and bilateral functional neck dissection. Final histopathology staging was pT0N1b. Radioactive iodine (RAI) screening showed residual functioning thyroid and later therapeutic RAI was administered. He has been on regular follow up and disease free for 1 year post treatment. Occult thyroid carcinoma is a rare diagnosis with multiple treatment plans. Few hypothesis for this entity includes tumor regression, ectopic thyroid carcinoma or missed pathological findings.