Eleven cases of medullarly thyroid carcinomas (MTC) were evaluated in relation to the pattern, immunohisto-chemistry and electron microscopy. Six cases were classified as classical MTC with histochemical evidence of amyloid and 5 cases were atypical without histochemical evidence of am­yloid . Immunostaining for thyrocalcit-onin was positive in 4 out of 6 classi­cal and 2 out of 5 atypical MTC cases. The neurosecretory granules were found in both the typical and the atypical MTC cases. The ultrastructu-ral examination is essential in the di­agnosis of MTC particularly where the histological and immunohistochemical evaluation is inconlusive. ABSTRACT
Eleven cases of medullarly thyroid
carcinomas (MTC) were evaluated in relation to the pattern, immunohisto-chemistry and electron microscopy. Six cases were classified as classical MTC with histochemical evidence of amyloid and 5 cases were atypical without histochemical evidence of am­yloid . Immunostaining for thyrocalcit-onin was positive in 4 out of 6 classi­cal and 2 out of 5 atypical MTC cases. The neurosecretory granules were found in both the typical and the atypical MTC cases. The ultrastructu-ral examination is essential in the di­agnosis of MTC particularly where the histological and immunohistochemical evaluation is inconlusive.