Immunohistochemical detection of nm23/NDP kinase and cathepsin D in medullary carcinomas of the thyroid gland.

Reduced expression of nm23/NDP kinase and increased expression of cathepsin D seem to be correlated with the high metastatic potential in a variety of malignancies. The expression of nm23/NDP kinase and that of cathepsin D have been evaluated by means of an immunohistochemical technique in paraffin-embedded tissues from 44 primary medullary carcinomas of the thyroid gland (MCT) and from the corresponding lymph node metastases in 32 of these cases. In addition, lymph node metastases from 4 cases were studied. We found that 36 of 44 (82%) primary and 26 of 36 (72%) lymph node metastatic MCT were nm23/NDP kinase positive, whereas 14 of the 44 (32%) primary and 17 of the 36 (47%) lymph node metastatic MCT were cathepsin D positive. We found no indication that the nm23/NDP kinase level has any prognostic significance in MCT. The cathepsin D level is close to being prognostically significant in this study, and we cannot exclude the possibility that it could be of prognostic value. However, it seems to be quite weak, and therefore of little use in a clinical situation.