Medullary thyroid carcinoma: Immunohistochemical and ultrastructural study

ABSTRACT

11 cases of medullary thyroid carcinomas [MTC] were evaluated in relation to the pattern, immunohistochemistry and electron microscopy. Six cases were classified as classical MTC with histochemical evidence of amyloid and 5 cases were atypical without histochemical evidence of amyloidosis. Immunostaining for thyrocalcitonin 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 ultrastructural study is essential in the diagnosis of MTC, specially where the histological and immunohistochemical evaluation is not definite