Clear cell thyroid cancer--undifferentiated type--an immunohistochemical and electron microscopical study.

: Two cases of clear cell thyroid cancer are described. In both tumors immunohistochemical methods detected the presence of intracytoplasmic thyroglobulin that confirmed the follicular origin. Simultaneously performed electron microscopic studies visualized the accumulation of smooth surfaced, membrane coated vesicles of varying size in the cytoplasm. Bad prognosis predicted on the base of undifferentiated histological structure was confirmed by extended hematogenic metastases.