A unique simultaneous occurrence of paratracheal granular cell tumor and papillary thyroid carcinoma.

We report an unusual case of granular cell tumor in the paratracheal region detected during total thyroidectomy for papillary carcinoma and clinically misdiagnosed as tracheal infiltration of thyroid neoplasia. Histologically, the granular cell tumor had infiltrated the thyroid gland close behind the papillary carcinoma. At immunohistochemical investigation, the cells showed diffuse positivity for S-100, neuron-specific enolase, and CD68, and surprisingly, positivity also for galectin-3 and HBME-1. A granular cell tumor should also be considered in the cytologic differential diagnosis of the thyroid and paratracheal nodules.