COLUMNAR CELL TYPE OF THYROID PAPILLARY CARCINOMA: THE DIAGNOSTIC CHALLENGES

*Dr. Swagata Dowerah, M.D., Dr. Mondita Borgohain, M.D., Dr. Ashim Manta, M.D.

ABSTRACT

Introduction: Columnar cell variant of papillary carcinoma thyroid is one of the rarest morphological subtypes of this tumor. Typical nuclear features of papillary carcinoma like ground glass nuclei, nuclear grooves and intranuclear inclusions have not been found to be consistently present in this neoplasm creating difficulties in diagnosis. Case history: A 30year old female presented with neck swelling of 7 months duration. There was no history of pain or fever, and on examination, a diffuse swelling was seen which moved on deglutition. USG neck revealed multiple hypoechoic SOL in both lobes of thyroid in a background of sub acute thyroiditis. Initial FNA gave a diagnosis of follicular neoplasm with lymphocytic thyroiditis. On histopathological examination, H & E stained sections revealed papillary structures lined by elongated cells showing nuclear stratification. The typical optically clear nuclei of papillary carcinoma was not seen. Other areas showed normal colloid filled thyroid follicles with evidence of lymphocytic thyroiditis. A diagnosis of papillary carcinoma thyroid, columnar cell type was given. On re examining the FNA slides, focal areas with papilla formation were seen lined by columnar cells with round to oval nuclei showing pseudostratification at places, abundant cytoplasm, inconspicuous nucleoli. Intranuclear inclusions and nuclear grooving was absent as also the powdery chromatin on MGG stained smears. Final diagnosis was columnar cell variant of papillary cancer. Conclusion: Columnar cell type of papillary thyroid cancer is a distinct morphological variant which is often missed on FNA smears and may cause diagnostic confusion even in tissue samples. Knowledge of the distinctive morphological features of this tumor is essential for correct diagnosis.

Keywords: papillary carcinoma, thyroid, columnar cell.