Giant prolactinoma presented as unilateral exophthalmos in a prepubertal boy: response to cabergoline

We report the case of a giant prolactinoma in a 7-year-old boy, which was complicated by unilateral exophthalmos. The initial levels of prolactin (PRL) were about 80,000 microU/ml. Treatment with cabergoline (CAB) resulted in rapid normalization of serum PRL (6 weeks after initiation of treatment) and reduction of tumor size. In particular, magnetic resonance imaging (MRI), which was done 2.5 months after the patient was put on CAB, revealed tremendous improvement with a decrease in the size of the tumor which now showed no extrasellar extension. Subsequent MRI studies demonstrated further improvement. Exophthalmos, anisocoria and visual fields improved. In summary, this patient represents the first report of the therapeutic use of CAB as the primary mode of treatment in a 7-year-old boy with infiltrative giant prolactinoma complicated by unilateral exophthalmos. It is a noninvasive treatment that can preserve and restore vision, as well as pituitary function, and is preferable to surgery or radiation in the treatment of prolactin-secreting macroadenoma in childhood and adolescence.