The Great Imitator: A Case of Secondary Neurosyphilis With Unusual Neurological Manifestations

Neurosyphilis, a central nervous system infection caused by the bacterium <i>Treponema pallidum</i>, is becoming increasingly rare due to the widespread use of antibiotics. However, unusual presentations continue to pose diagnostic challenges. We report a case where a patient presented with progressive neurological symptoms, initially mimicking other systemic and neurological disorders. A 52-year-old man presented with abdominal pain associated with fever and loose stools with per rectal bleeding and accompanied by progressive lower limb paresthesia and numbness. Over subsequent visits, he developed a widespread maculopapular rash, right-sided Bell's palsy, and ascending sensory loss involving the perianal and genital regions. Serial laboratory investigations initially revealed elevated inflammatory markers and abnormal liver function tests, which gradually improved. Initial viral and autoimmune screens were inconclusive. The MRI of the brain and spine was unremarkable; however, the CSF analysis revealed mildly elevated protein levels. On further testing, <i>Treponema pallidum</i> serology returned positive, confirming secondary neurosyphilis. He received intravenous ceftriaxone 2 g once daily for 10 days, leading to complete resolution of symptoms. This case highlights variable features of secondary syphilis, which can resemble a range of systemic, infectious, and neurological conditions. Furthermore, initially, the patient denied any history of unprotected intercourse. Following the positive syphilis serology results, he acknowledged recent, unprotected sexual activity while on holiday. Therefore, a key learning point is that clinicians need to create a confidential and supportive environment that facilitates accurate disclosure, thereby aiding in timely diagnosis and treatment. Secondary neurosyphilis can present with various neurological and systemic features, often disguised as other disorders. Early detection and antibiotic therapy are vital for complete recovery. This case also highlights the importance of gathering confidential and non-judgmental information to uncover essential details that directly impact patient management and outcomes.