Hyalinizing trabecular tumor is a rare neoplasm usually with benign clinical behavior. Exceptionally it shows characteristic features of malignant tumors, such as the presence of venous or capsular invasion or distant metastasis. We report the case of 45-years-old female with a palpable nodule in the right lobe of the thyroid gland, 8x8x10 mm in size, well circumscribed, white colored. Histologically it was an encapsulated follicular neoplasm that consisted of medium to large-sized spindle-like to polygonal cells with elongated to round-shaped nuclei and small prominent nucleoli, sporadically with nuclear grooving and intranuclear pseudoinclusions, growing in alveolar to trabecular pattern. The tumor cells showed a distinctive membranous positivity for Ki-67. The tumor was surrounded by a thin fibrous capsule with multifocal transcapsular invasion. Keywords: hylinizing trabecular tumor - transcapsular invasion - thyroid gland - Ki-67.

Total thyroidectomy can still remain the method of choice in some Bethesda III cases