A 26-year-old woman is brought mute and immobile in posturing. Over 12 hours she develops fever of 39.5 degrees, generalised rigidity, tachycardia, and labile blood pressure. She has never received any antipsychotic medication. Which is the MOST likely diagnosis?

• A Neuroleptic malignant syndrome
• B Malignant catatonia ✓
• C Serotonin syndrome
• D Anticholinergic toxidrome

Explanation

Malignant catatonia is clinically indistinguishable from NMS in its fever, rigidity, and autonomic instability, but it arises from untreated catatonic illness itself with no neuroleptic exposure. The absence of any antipsychotic history excludes NMS. Serotonin syndrome requires serotonergic drug exposure and shows clonus and hyperreflexia rather than lead-pipe rigidity. Anticholinergic toxicity causes dry skin, dilated pupils, and agitation rather than muteness and posturing.

Reference: Kaplan and Sadock's Synopsis of Psychiatry, 12th ed.

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