Immunohistochemical studies of chromogranins (A and C) in pituitary adenomas

Expression of Chromogranin A and C was examined immunohistochemically on 45 surgically obtained pituitary adenomas. Positive rate of chromogranin A was 40.0% and chromogranin C was positive in 8.0% of 45 pituitary adenomas. Chromogranin A was expressed frequently in adenomas in which at least one of the FSH alpha, FSH beta, LH beta and TSH beta subunits was positive. It also expressed frequently in non-functioning adenomas. The positive rate of chromogranin A was low in GH or PRL positive adenomas. These findings suggest that chromogranin could be a parameter of the functional differentiation of the pituitary adenomas.