Recent studies have shown an increase in the prevalence of infectious syphilis. If not treated, 30% of patients may develop tertiary syphilis, where neurosyphilis is included. Neurosyphilis can present a variety of psychiatry symptoms, including mania, depression, psychosis and dementia.

The authors present a case of a persistent psychosis (similar to late schizofrenia) with 3 years of evolution in a 42-years old man. In the first hospitalization, the patient was clinically studied, namely with Venereal Disease Research Laboratories (VDRL) that was negative. Other possible causes for psychosis were excluded. His clinical state never improved significantly despite the high doses of antipsychotics.

The hypothesis of syphilis was deeply studied with Fluorescent Treponemal Antibody-Absorption (FTA-ABS) and Treponema Pallidum Hemaglutination Assay (TPHA) which revealed positive results.

A lumbar puncture was performed and cerebrospinal fluid analysis resulted in the diagnosis of neurosyphilis. The Computerized Axial Tomography (CAT) had no abnormalities. The patient started the course of treatment for neurosyphilis with endovenous penicillin G.

After the treatment of neurosyphilis, steady improvements were noted in psychotic and cognitive symptoms. After his discharge from the hospital he was medicated only with Lorazepam S.O.S.

This case emphasizes that neurosyphilis still has to be considered in the differential diagnosis within the context of psychiatric disorders even with no other signals suggesting this diagnosis. Psychiatric symptoms and cognitive dysfunction intensely respond to the correct treatment of neurosyphilis. Furthermore, this case shows that we should be alert for the VDRL false negatives