CHROMOGRANIN-A IMMUNOREACTIVITY COMPARED WITH ARGYROPHILIA, CALCITONIN IMMUNOREACTIVITY, AND AMYLOID AS TUMOR-MARKERS IN THE HISTOPATHOLOGICAL DIAGNOSIS OF MEDULLARY (C-CELL) THYROID-CARCINOMA

Applying the WHO criteria for the histopathological diagnosis of medullary thyroid carcinoma (MTC) - as well as the criterion that a significant amount of argyrophil cells, amyloid deposits, or calcitonin (CT) immunoreactive cells shall be present - 122 cases were identified from the files of the Swedish Cancer Registry. Both non-occult (n = 110) and "occult" ( < 1 cm in diameter) (n = 12) MTCs were included. Both primary tumours (n = 91) and metastatic lesions (n = 31) were investigated. The specimens available were all only conventionally formalin-fixed and paraffin-embedded. The presence of neoplastic cells immunoreactive with antisera against chromogranin A (Chr A) was compared with that of the other three MTC markers. Chr A immunoreactive cells were present in practically all the cases. Similar results were obtained when the argyrophil reaction alone and CT immunoreactivity alone were used as markers. When two of the three MTC markers were combined, it was found that virtually everyone of the 122 tumours could be identified as a MTC. In contrast, the presence of amyloid deposits was found to be a less constant MTC marker; whereas 94% of the primary tumours had amyloid deposits, they were present in only approximately 70% and 60% of the metastatic and "occult" tumours respectively. No differences in the staining reaction patterns were found between familial (n = 18) and the sporadic (n = 104) types of MTC. When the neoplasms were further subclassified into 9 histopathological types, it was found that no remarkable differences existed between the different MTC variants with regard to their content of argyrophil cells, and in that of cells being immunoreactive with antisera against CT and Chr A. As regards amyloid deposits, however, they were particularly often lacking not only in "occult" MTCs, but also in the poorly differentiated MTC subtype. A co-localization between the argyrophilia and the immunoreactivity against Chr A and/or CT was only partly observed.