Rare Case of Visual Hallucinations in a 60-year-old Female with a Recurring Pituitary Macroadenoma

Pituitary adenomas are the third most frequently occurring primary intracranial tumor and are benign neoplasms that can have profound clinical implications. While most of these masses cause hormone hypersecretion, they may also be clinically silent until they elicit symptoms of mass effect, including severe headaches and visual field defects such as bitemporal hemianopia. This report highlights an atypical presentation of a pituitary adenoma that could be valuable for internists to consider when forming a differential diagnosis for patients with hallucinations. We discuss a case of a 60-year-old woman with a recent history of multiple emergency department visits for ongoing urinary symptoms and visual hallucinations. Despite initial diagnosis and treatment for a urinary tract infection, her persistent visual hallucinations necessitated the use of antipsychotic and benzodiazepine pharmacotherapy. She was ultimately diagnosed with a recurring macroprolactinoma, which prompted her transfer to a tertiary care center for neurosurgical intervention. After undergoing transsphenoidal pituitary adenoma resection, her hallucinations resolved. The underlying mechanism of this case may be Charles Bonnet syndrome (CBS), a rare phenomenon characterized by visual hallucinations due to decreased visual acuity. This is supported by the gradual regression of the patient’s hallucinations and simultaneous improvement of visual acuity following transsphenoidal resection. This case demonstrates visual hallucinations as a presenting symptom of pituitary macroadenomas with CBS as a likely etiology. By recognizing visual hallucinations in the symptomatology of pituitary adenomas, internists can avoid misdiagnosis and unnecessary treatment in the future.