An Unexpected Combination of Prolactinoma and Septo-Optic Dysplasia

ABSTRACT Objective To describe the unusual finding of pituitary adenoma in a patient with septo-optic dysplasia (SOD). Methods We describe the clinical presentation, biochemical and radiological evaluation, treatment, and outcomes of a patient with macroprolactinoma and previously undiagnosed SOD. Results A 41-year-old woman with optic nerve hypoplasia and growth hormone deficiency presented with new-onset galactorrhea, polyuria, and polydipsia. Physical exam was notable for bilateral galactorrhea. Laboratory workup showed a prolactin level of 176 μg/L (reference range is 6 to 20 μg/L), serum cortisol of 7.7 μg/dL (reference range is 5.0 to 20.0 μg/dL), and adrenocorticotropic hormone of 54 pg/mL (reference range is 0 to 46 pg/mL). Thyroid function and pituitary-gonadal axis testing were normal. Low-dose cosyntropin test showed a borderline cortisol response and persistently low adrenal androgens, suggestive of partial secondary adrenal insufficiency. A water deprivation test showed evidence of diabetes insipidus (DI). Magnetic resonance imaging of the sella showed a 1.0 × 1.0 × 1.5-cm mass compatible with pituitary adenoma, absence of septum pellucidum, and atrophy of the optic nerves. The patient was diagnosed with SOD with partial hypopituitarism and a concomitant macroprolactinoma of more recent onset resulting in DI. The patient was treated with cabergoline with good clinical and biochemical response including resolution of DI symptoms. Subsequent magnetic resonance imaging of the sella showed near resolution of the prolactinoma. Conclusion We conclude that a diagnosis of SOD should not exclude the possibility of a pituitary adenoma in the appropriate clinical context, and that the pattern of hormonal deficits in such a combination may be uncharacteristic of the deficits expected with pituitary adenoma alone.