If a prolactinoma is left untreated, what is the risk of tumor enlargement?
Many longitudinal studies agree that progression of the disease is rare and occurs at a slow pace. This is particularly true of small prolactin-secreting tumors (< 10 mm), < 5% of which enlarge significantly over 25 years of observation. There is no reliable way to predict which tumors will show progression. Spontaneous resolution, attributed to necrosis, has also been described in some patients, particularly after pregnancy.