Posterior reversible encephalopathy syndrome in a patient with metastatic breast cancer: A case report

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic encephalopathic state with clinical symptoms such as headache, altered consciousness, visual disturbances, and seizures. Vasogenic edema occurs predominantly in the posterior occipital and parietal lobes of the brain. PRES is caused by various diseases, and its mechanism remains unclear. However, it can be easily diagnosed based on characteristic lesions on magnetic resonance imaging. CASE SUMMARY: A 51-year-old woman with unremarkable past medical history presented with progressively worsening back pain since 2 mo. Physical examinations revealed paralumbar muscle tenderness, a large lesion on the right breast and several mass-like lesions on both breasts. The blood pressure (BP) was elevated (150/90 mmHg), and did not respond to antihypertensive medication. On the seventh day of hospitalization, she exhibited a confused mental status and generalized tonic-clonic seizures. On magnetic resonance imaging, bilateral cortical and subcortical edema of the occipital lobes, suggestive of PRES, was observed. The serum calcium was 15.8 mg/dL. After two days of treatment with nicardipine, elcatonin, and zolendronic acid, her BP was 130/91 mmHg and serum calcium was 10.1 mg/dL. The patient regained consciousness and her mental status improved. Fluorodeoxyglucose-positron emission tomography revealed right breast cancer with extensive metastases. CONCLUSION: Although rare, hypercalcemia can lead to PRES by causing uncontrolled hypertension. Prompt diagnosis can help prevent severe mental disturbances and even death.