Leiomyoma and neurilemoma: report of two unusual non-epithelial tumours of the thyroid gland.

Two primary spindle cell tumours of the thyroid are described showing light microscopic features of leiomyoma and neurilemoma respectively. The origin from smooth muscle and nerve sheath was confirmed by both immunohistochemical reactions and ultrastructural findings. Review of the literature reveals only one case of leiomyoma and three cases of neurilemoma reported as developing within the thyroid gland. Our observations further support the view that leiomyoma and neurilemoma may occur at this unusual site and are recognizable entities.