CT of follicular adenoma in the thyroid gland

Computed tomography was performed in 27 lesions of follicular adenoma. About half of them showed heterogeneous low density areas due to retrogressive changes, especially internal hemorrhage. Seven out of 12 lesions whose contours were poorly defined had chronic focal thyroiditis of the adjacent thyroid gland. Internal hemorrhage was another cause of indistinct contour in two lesions. We stress that CT features of follicular adenomas are modified by their retrogressive changes and inflammation of the adjacent gland.