Relative resistance of a macroprolactinoma to bromocriptine therapy during pregnancy

A woman presented with a pituitary macroadenoma with extensive suprasellar extension. Her initial response to bromocriptine therapy was good, allowing subsequent trans-sphenoidal surgical treatment. The tumor grew during pregnancy despite continued bromocriptine therapy, but it returned to prepregnancy size postdelivery. There have been conflicting reports regarding the growth of pituitary tumors in pregnancy. Most recognize that some growth may occur, but only a small percentage of patients are reported to become symptomatic from the growth. Resistance to bromocriptine has been reported in non-pregnant patients. Patients who have had surgery or radiation therapy and did not receive bromocriptine treatment during pregnancy have been reported to have symptomatic growth of their residual tumor. This case demonstrates an unusual tumor that became resistant to bromocriptine during pregnancy, but whose sensitivity to the drug returned postdelivery.