Reduction of pituitary tumor size with clinical and biochemical improvement with bromocriptine in a normoprolactinemic Cushing's disease.

We report a 37-year old Japanese female patient with Cushing's disease who was treated with a large daily dose of bromocriptine, which resulted in the reduction of the pituitary tumor size with clinical and biochemical improvements. On admission, the pituitary tumor size detected by magnetic resonance imaging (MRI) was 12.4 x 11.1 x 6.2 mm. Both the basal plasma prolactin level and its response to TRH test were normal. The patient was treated with bromocriptine at 5 to 35 mg/day. With 35 mg daily, 24-h urinary free cortisol started to decrease and eventually became normal. Four months after initiation of treatment with the drug, there was clinical remission with normalization of suppressibility of plasma cortisol with 1 mg dexamethasone. Repeated examination of the pituitary fossa by MRI showed a marked reduction in the tumor size (6.3 x 6.2 x 2.4 mm). This is a very rare case in which treatment with bromocriptine resulted in a reduction of the pituitary tumor size as well as clinical and biochemical improvements in a patient with normoprolactinemic Cushing's disease.