Neuropsychiatric manifestations such as anxiety, mood disorders, and psychosis are frequent features of systemic lupus erythematosus. A psychosis prevalence of 5% has been reported. ^{Reference Brey, Holliday, Saklad, Navarrete, Hermosillo-Romo, Stallworth, Valdez, Escalante, del Rincón, Gronseth, Rhine, Padilla and McGlasson1,Reference Haddad and Dursun2} Neuroleptic malignant syndrome is a life-threatening complication of treatment with antipsychotics. ^{Reference Haddad and Dursun2} High-potency antipsychotics increase the risk.

We report the clinical case of a 23-year-old woman presenting early-onset neuropsychiatric systemic lupus erythematosus with interstitial pneumopathy, glomerulonephritis and malar rash. When she was 20 years old, she had been hospitalised for her first episode with acute psychotic symptoms (mystic delusions) and agitation. The introduction of droperidol led to a neuroleptic malignant syndrome with high creatinine phosphokinase levels, muscular rigidity, hyperthermia and blood pressure dysregulation. The droperidol was stopped and benzodiazepines were used.

The patient was rehospitalised when she was 23 years old in a similar state because she had not observed the immunosuppressant treatment. No new gliotic cerebral lesions appeared on cerebral magnetic resonance imaging. The psychiatrist decided to introduce valproic acid and benzodiazepines in order to avoid antipsychotics. However, the mental state of the patient quickly led to delirium with repetitive, delusional and incoherent speech and behaviour. Despite the risk of neuroleptic malignant syndrome, a one-shot intramuscular injection of clotiapine was administered. Once again, we observed muscular rigidity, dehydration (148 mEq/l natrium) and systolic hypertension. Her clinical state became serious with lethargy, aspontaneity, disinhibition and executive dysfunction.

Biological features were abnormal with elevated creatinine phosphokinase (3415 UI/l), increased C-reactive protein (3.7 mg/dl) and hepatic cytolysis. Her treatment consisted of cyclophosphamide and methylprednisolone, and the introduction of a titrating-dose (up to 600 mg) of quetiapine for the psychiatric symptoms was decided upon. Her creatinine phosphokinase levels returned progressively to normal, and no signs of neuroleptic malignant syndrome were observed. Six weeks after continuing this treatment, biological and clinical features were normalised.

This case illustrates the importance of differentiating delirium caused by a neuropsychiatric systemic lupus erythematosus, a steroid-induced delirium ^{Reference Brey, Holliday, Saklad, Navarrete, Hermosillo-Romo, Stallworth, Valdez, Escalante, del Rincón, Gronseth, Rhine, Padilla and McGlasson1} (which was not the case here as the patient had not been receiving any steroids when she developed the second psychotic episode) and an alteration in the consciousness level due to neuroleptic malignant syndrome, which was the case here.

Although there are no guidelines for the treatment of the psychiatric manifestations of systemic lupus erythematosus, it usually includes immunosuppressants associated with second-generation antipsychotics. ^{Reference Stojanovich, Zandman-Goddard, Pavlovich and Sikanich3} The diagnosis of neuroleptic malignant syndrome is based on muscle rigidity, hyperthermia, delirium and autonomic disturbances. ^{Reference Ananth, Parameswaran, Gunatilake, Burgoyne and Sidhom4} The dopaminergic hypothesis of the syndrome is well documented. ^{Reference Strawn, Keck and Caroff5} Neuroleptic malignant syndrome is not an absolute contraindication for further antipsychotic treatment and some factors can reduce that risk: avoiding the long-term use of antipsychotics, using low-potency agents, adjunctive treatments and slow titration. ^{Reference Haddad and Dursun2}

In this case, we suggest that the introduction of quetiapine – a lower D₂-affinity antipsychotic – was an interesting alternative.