Case One

Discussion and answer

Low power view demonstrates follicular cells arranged mainly in a microfollicular pattern. High power view demonstrates follicular cells with abundant cytoplasms. Nuclear features include finely granular chromatin, intranuclear cytoplasmic inclusions as well as nuclear grooves. Colloid is identified in the background. Architectural arrangement raises the possibility of a follicular lesion, however the nuclear features are in keeping with a papillary carcinoma.

Thyroidectomy was subsequently performed. A 2.5 cm diameter nodule of papillary thyroid carcinoma, follicular type (pT3, N1) was identified. Infiltration of the skeletal muscle was noted and focal tumour noted at the inked margin. Three of nine lymph nodes were positive for papillary carcinoma.