Intranuclear vacuoles in nonpapillary carcinoma of the thyroid. A report of three cases

Three cases of nonpapillary carcinoma of the thyroid are reported in which intranuclear vacuoles or (pseudo)inclusions were observed in fine needle aspiration smears. Two of the cases had medullary carcinoma; one had a poorly differentiated follicular carcinoma. The cytologic, histologic and ultrastructural appearances of intranuclear vacuoles and of the so-called ground-glass nuclei of papillary carcinoma are described, and the diagnostic significance of these findings is discussed briefly. Intranuclear vacuoles are distinct and different from ground-glass nuclei.