Abstract:
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 indistinguishable from MCT when scant necrosis is present, but
differentiation of the two lesions is important for further management.
