Paucicellular variant of anaplastic carcinoma of thyroid - Report of a case with cytologic and histologic findings

Abstract

The paucicellular variant of Anaplastic carcinoma of thyroid (ANTC) is an uncommon entity. It can pose diagnostic difficulty both in cytology and histology. Its recognition is important as it has an aggressive clinical course with poor outcome. We report here a forty two year old female patient who presented with a midline neck swelling and painful deglutition of three months duration. A diagnosis of subacute thyroiditis was entertained clinically and on initial cytologic evaluation. The subsequent frozen and paraffin section diagnosis considered was Riedei's thyroiditis. Patient's rapid clinical course and fatal outcome necessitated a review which led to the recognition of ANTC-paucicellular variant. Because of the paucicellular nature of the lesion, this variant is likely to be underdiagnosed in aspiration cytology. The clue to recognising it in histology lies in paying attention to the areas of cellularity, atypical cells and the infarcioid type of necrosis; features not associated with Riedei's thyroiditis.