[An autopsy case of undifferentiated carcinoma of the thyroid with sarcoma-like change]

Although undifferentiated carcinoma of the thyroid is rare, it is often seen in aged. Because of rapid growth and frequent remote metastasis, it has poor prognosis. We have reported an autopsy case of the undifferentiated carcinoma of the thyroid gland, which could be diagnosed in autopsy although it could not be diagnosed clinically. In autopsy, multiple tumors were found in the brain, left lobe of the thyroid gland involving regional lymph node, lungs, pancreas, intestinal mucosa and abdominal soft part. Histologically, the tumor cells showed pleomorphism with sarcoma-like change and some of the tumor lesions in the thyroid and lungs showed colloid follicles differentiation. Immunohistochemically, sarcoma-like tumor cells showed positive for anti-keratin staining and the colloid follicle pattern revealed positive for anti-thyroglobulin staining. And finally, the tumor of this case could be diagnosed as the undifferentiated carcinoma of the thyroid with general metastasis.