ABSTRACT
Epidemiology and pathogenesis Prolactinomas are the most frequent of the hormonesecreting pituitary tumours. Earlier studies reported the prevalence of prolactinomas at 100 cases per million adults,1 but a recent study determined that the prevalence may be up to 7-fold higher.2 Prior to menopause, the incidence of prolactinomas is 10-fold greater in women than in men, but after menopause and in autopsy series sex-related differences in the prevalence of these tumours disappear. Microprolactinomas (tumours <1 cm in diameter) occur more commonly in women, whereas macroprolactinomas (tumours >1cm in diameter) occur in equal numbers of women and men. The greater prevalence of microprolactinomas in younger women may reflect the fact that mild hyperprolactinaemia results in more symptoms in women than in men thus bringing them to clinical attention. However, there may also be gender-specific biological differences in the behaviour of these tumours. Fewer than 100 cases of malignant prolactinomas have been reported.3
Virtually all prolactinomas are sporadic, but familial cases of prolactinomas may occur, usually in association with multiple endocrine neoplasia type 1.1
