Rationale:Posterior reversible encephalopathy syndrome (PRES) is a rare but potentially life-threatening neurological condition. In patients with systemic lupus erythematosus (SLE), PRES can occur as a complication of hypertension, renal dysfunction, or immunosuppressive treatment, and is often difficult to distinguish from neuropsychiatric lupus.Patient concerns:A 17-year-old woman was diagnosed with SLE, presenting with fever, hypertension, and severe lower limb edema. Laboratory investigations revealed low serum complement levels, positive ANA and ds-DNA, nephrotic range proteinuria, elevated serum urea and creatine, anemia, and thrombocytopenia.Diagnoses:SLE with PRES.Interventions:The patient promptly received methylprednisolone pulse therapy and cyclophosphamide for the lupus flare, along with symptomatic and supportive treatment, including antiepileptic drugs, blood pressure control, and renal replacement therapy. Her condition improved with the resolution of imaging features of PRES within 2 weeks. However, 8 weeks later, seizures recurred, and a repeat brain magnetic resonance imaging revealed a worsening of PRES. Notably, laboratory tests did not indicate SLE exacerbation. Blood pressure control was further intensified, and intensive hemodialysis was administered. The induction therapy, including corticosteroids and cyclophosphamide, was continued.Outcomes:The patient's PRES symptoms, including headache, seizures, loss of vision, and frequent vomiting, significantly improved. She was successfully discharged and follow-up examinations confirmed the resolution of PRES and stable SLE.Lessons:The symptoms of PRES in SLE patients can mimic those of neuropsychiatric systemic lupus erythematosus. Timely differential diagnosis and appropriate treatment are crucial to reduce the recurrence of PRES and improve patient prognosis.