A 32 year old male with painless lymph node in cervical region. Lymph node biopsy shown normal thyroid gland features. The thyroid is normal on palpation clinically. The diagnosis is

Thyroid tissue present in cervical lymph nodes in the face of a clinically normal thyroid gland is a metastasis from an occult primary thyroid carcinoma Occasionally, a metastatic papillary thyroid cancer manifests as a painless lateral neck mass that is clinically detected before detecting the primary thyroid lesion. Comment: Normal thyroid tissue is a trap by examiner, remeber in young people papillary thyroid cancer mostly is well differentiated. Well differentiated cells look like normal cells and tend to grow .and spread more slowly than poorly differentiated cells (anaplastic carcinoma). Sabiston 20th edition pg 926