Increased serum prolactin levels have numerous causes, but significant hyperprolactinemia always raises the suspicion of hypothalamic or pituitary disease, especially prolactinoma.1 It is highly unusual, however, for a primary brain tumor to present as isolated hyperprolactinemia.
A healthy, 25-year-old, single woman consulted a dermatologist because of facial skin lesions. Several laboratory tests were performed, and increased serum prolactin levels of 57 µg/L (reference range, <20 µg/L) were the only abnormality found. The patient was not taking any medications, and a second test performed using a previously inserted venous cannula after she had rested again yielded high serum prolactin levels of 63 µg/L. This test was followed by a computed tomographic scan of the brain and sella turcica, which showed no abnormality. The patient's menses were regular and there was no galactorrhea or reports of other abnormal physical findings at that time. Twelve months later, the patient presented with neck pain that increased after coughing, and she was examined and treated by an orthopedic surgeon with no improvement. After 10 days, occasional vomiting appeared and persisted. A gastroenterologist was consulted, and findings from gastroscopy revealed no notable pathological features except mild gastritis. After experiencing neck pain and recurrent vomiting (3-4 times per day) for 2 weeks, the patient was admitted for evaluation. A review of systems revealed recent (several days) reports of pain around the right orbit, unfocused vision in the right eye, and fullness of the breasts. Findings from a physical examination were notable for a marked limitation of neck flexion with borderline Brudzinski sign, mild left hemiparesis (more pronounced in the left arm than in the left leg), and hyperreflexia. Plantar reflexes were flexor, and the optic fundi and visual fields were normal. Findings from the remainder of the physical examination and a full laboratory evaluation were unremarkable. However, a serum prolactin level of 950 µg/L was found. A brain computed tomographic scan showed a right paraventricular hyperdense mass (2 × 2 cm). Brain biopsy (performed with the stereotactic approach) identified the mass as glioblastoma multiforme. One day later, sudden transient loss of consciousness occurred, and a brain computed tomographic scan demonstrated bleeding within the tumor. Dexamethasone and phenytoin were administered, but the patient continued to lose consciousness. Lumbar puncture revealed a high opening pressure and a meningeal spread of the tumor. A ventriculoperitoneal shunt was installed with no effect, and the patient died less than 60 days after she had first reported neck pain.
Schattner A. Glioblastoma Multiforme Presenting as Asymptomatic Hyperprolactinemia. Arch Intern Med. 1998;158(17):1952. doi:https://doi.org/
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