Argyrophilia and chromogranin A and B immunostaining in patients with sporadic medullary thyroid carcinoma. A critical appraisal of their prognostic utility.

The purpose of the present study was to evaluate the prognostic utility of tumour argyrophilia and chromogranin A (CgA) and B (CgB) immunocytochemical expression in patients with sporadic medullary thyroid carcinoma. To this end, the histo-immunocytochemical data on a consecutive series of 99 such tumours were submitted to statistical analysis. In univariate analysis, a significantly increased risk of disease progression and death was present in patients with CgA-poor and CgB-poor tumours, respectively. Multivariate analyses were performed by adding the histo-immunocytochemical variables to the final (reference) models obtained in earlier work on the same case series, in which 18 clinicopathological variables had been taken into account. This addition did not change the prognostic impact of the variables considered in the two reference models; it did, however, increase the prognostic information for overall survival, since the adjunctive contribution of CgB immunocytochemical expression (as assessed by the likelihood ratio test) was statistically significant. It is concluded that the chromogranin B immunostaining pattern of the primary tumour allows the distinction of patients with an increased risk of death. Argyrophilia and expression of chromogranin A seem instead to be of no prognostic value in patients with sporadic medullary thyroid carcinoma.