Lack of demonstrable tumor growth in progressive hyperprolactinemia.

Prolactin has been regarded as an excellent tumor marker for patients harboring prolactinomas, and a significant rise in the basal prolactin level is generally regarded as being commensurate with tumor growth. This report describes a case in which the basal serum prolactin level rose from 250 ng/ml to 1,528 ng/ml over a 10-year follow-up period in the absence of definitive therapy. Three sequential contrast-enhanced direct coronal computed tomographic scans obtained over a four-year period failed to demonstrate any evidence of growth of the 5 mm microprolactinoma. Progressive hyperprolactinemia may not be synonymous with tumor growth in patients with microprolactinomas.