Growth potential of female prolactinomas

BACKGROUND The indications for treatment in female patients with small prolactinomas and mild or no symptoms are controversial. The aim of this study was to investigate whether we can predict the growth potential of a given small prolactinoma. METHODS The proliferation potential of 25 female prolactinomas and 5 prolactin-containing adenomas found incidentally at autopsy was determined immunohistochemically using the Ki-67 (MIB-1) antibody. The results were compared according to age, clinical and endocrine findings, and tumor volume. RESULTS Small prolactinomas (<1.0 cm³) with mild hyperprolactinemia (<150 ng/mL) showed significantly low proliferation potential irrespective of age, resembling prolactin-containing adenomas found at autopsy. The patients tended to present with mild symptoms and rarely had estrogen deficiency. CONCLUSION These findings indicate that female patients with a small prolactinoma, mild hyperprolactinemia, and no symptoms or those who do not desire fertility may have no specific reason for treatment, but can be followed by serum prolactin level and serial magnetic resonance imaging.