Fever, confusion, acute kidney injury: is this atypical neuroleptic malignant syndrome following polypharmacy with clozapine and risperidone?

Objective: Clozapine is the gold-standard antipsychotic medication for treatment-refractory schizophrenia (TRS). However, one potentially lethal side effect of clozapine, as with other antipsychotics, is neuroleptic malignant syndrome (NMS) which could present differently in clozapine therapy. 'Atypical NMS' is a recognised variant of NMS with less rigidity and delayed elevation of creatine kinase; this variant is associated with clozapine. Method: A case from the author's clinical practice was reviewed. Results: A 67-year-old man with TRS was treated with clozapine. Unfortunately, his physical condition deteriorated and he presented with atypical NMS, which initially was treated as presumable urinary tract infection. Conclusions: Atypical NMS is associated with clozapine. This case exposes the potential difficulties in diagnosis, and highlights the importance of considering less common diagnoses in acutely unwell psychiatric patients