Acute Psychosis as the Initial Presentation of Systemic Lupus Erythematosus Complicated by Posterior Reversible Encephalopathy Syndrome With Hemorrhage: A Case Report.

Acute psychosis may rarely represent the initial presentation of an underlying systemic and potentially life-threatening medical disorder, posing significant diagnostic and management challenges. We report the case of a young woman with no prior psychiatric history who presented with abrupt-onset psychosis and behavioral disturbance. Early neuroimaging revealed posterior-predominant vasogenic edema with associated intracerebral hemorrhage, consistent with posterior reversible encephalopathy syndrome (PRES). Further evaluation demonstrated hematological abnormalities, renal involvement, and positive autoimmune serology, leading to the diagnosis of previously unrecognized systemic lupus erythematosus (SLE) with neuropsychiatric involvement. The patient was managed with blood pressure control, immunosuppressive therapy, and supportive neurological and psychiatric care, resulting in marked clinical and radiological improvement. This case emphasizes the importance of maintaining a broad differential diagnosis when evaluating acute psychosis, particularly in young patients with atypical features or abnormal neurological findings. Early neuroimaging and comprehensive systemic workup were critical in identifying a reversible neurological syndrome secondary to an autoimmune disease, allowing timely intervention and a favorable outcome. The report highlights PRES as an important and potentially reversible cause of acute neuropsychiatric symptoms in SLE and underscores the need for multidisciplinary collaboration to optimize diagnosis, treatment, and prognosis in such complex presentations.