Anaplastic thyroid carcinoma (ATC) is most aggressive malignancy with an incidence of 1 - 2%. It is common in sixth decade of life with female predominance. Fine needle aspiration (FNA) is an important tool and provides correct diagnosis of ATC in upto 90% of cases. On cytology, ATC shows high cellularity smears composed of pleomorphic population of cells in a necrotic background.The three main patterns of ATC are spindle cell, giant cell, and squamoid. Spindle cell variant should be differentiated mainly from medullary carcinoma of thyroid( MCT) & Malignant fibrous histiocytoma The presence of amyloid in the smear is one of the distinguishing feature from MCT to ATC, but amyloid is not identified in all cases. Spindle cell variant of ATC may be ndistinguishable from MCT when scant necrosis is present, but differentiation of the two lesions is important for further management.There should be a high index of suspicion for anaplastic thyroid carcinoma when areas of necrosis is present on cytology Hence, we present a case of 60 year old female presented with midline neck swelling. Differential diagnosis of spindle cell variant of ATC and medullary carcinoma (MCT) was considered on cytologyand confirmed as ATC with residual papillary carcinoma of thyroid (PCT) on histopathology.