Higher magnification showing straight or curvilinear trabeculae, 2 to 4 cells thick, separated by hyalinized stroma. The cells are spindle, fusiform, or polygonal and contain elongated or oval nuclei often arranged perpendicular to the axis of the trabeculae. The nuclei show intranuclear cytoplasmic inclusions, irregular contours and prominent grooves. The differential diagnosis includes papillary carcinoma, follicular adenoma/carcinoma, medullary thyroid carcinoma, and even paraganglioma. The treatment of hyalinizing trabecular adenoma is usually conservative surgical resection (lobectomy).