GROWTH OF A MICROPROLACTINOMA TO A MACROPROLACTINOMA DURING ESTROGEN THERAPY

Following presentation and diagnosis, microprolactinomas usually follo w a benign course and rarely progress to macroprolactinomas. However, clinically significant enlargement of prolactinomas during pregnancy, presumably related to estrogen stimulation, has been reported, This re port describes a patient with amenorrhea and hyperprolactinemia and a microadenoma by computed tomography scan who developed a macroprolacti noma within 10 months after being placed on estrogen therapy, We propo se that exogenous estrogen administration in this patient most likely promoted growth from a microprolactinoma to a macroprolactinoma. This case emphasizes the primary role of dopaminergic agonist therapy in th e management of pathological hyperprolactinemia and suggests that estr ogen therapy should not be casually given to patients with known prola ctinomas to avoid the possibility of promoting tumor growth. A correla te of this approach is that caution regarding estrogen therapy should also be exercised in patients with idiopathic hyperprolactinemia who m ight have an occult microprolactinoma which could grow following estro gen stimulation. If estrogen treatment is deemed necessary, dopaminerg ic agonist therapy should also be used prophylactically to prevent pot ential tumor growth due to estrogen. The patient should then be carefu lly monitored with periodic serum PRLs and for the development of clin ical manifestations suggesting pituitary growth. An imaging study shou ld be performed when there is a significant increase in serum PRL or t he development of new clinical manifestations.