Case Presentation: A 56-year-old man presented with 3 weeks of headache and 3 days of chin numbness. He also reported subjective fever and night sweats. His past medical history included HIV for which he was on antiretroviral therapy (last CD4 902 x10^6/L and undetectable viral load). His vital signs were normal. He had decreased sensation of the lower lip and chin without other neurologic deficits. Complete blood count and basic metabolic panel were normal, but aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase were elevated at 68, 112, and 370 respectively. Lumbar puncture showed bland cerebrospinal fluid. T2 hyperintensity involving the pituitary infundibulum and bilateral mental nerves was seen on MRI of the face and brain, suggestive of inflammation or infiltration. The patient’s presentation was concerning for Numb Chin Syndrome (NCS), often associated with metastatic malignancy; a CT of the chest, abdomen and pelvis was performed and revealed >20 hepatic lesions [Figure 1a]. Per patient request he was discharged to complete liver biopsy as an outpatient. One week later, the patient presented to his HIV provider with persistent headache, fever, chin numbness, and a diffuse, papulopustular rash. Further history revealed a recent sexual partner with known syphilis exposure. Rapid plasma reagin was newly elevated at ≥ 1:256 from 1:4 three months prior. A diagnosis of secondary syphilis with dermatologic, hepatic, central nervous system (CNS), and peripheral nerve involvement was made. The patient completed a 14-day course of intravenous penicillin G with prompt resolution of fevers, rash, and headache. Serial CT scans at one- and five-months following treatment showed interval decrease in the size of his hepatic lesions [Figure 1b] without new lesions. His liver enzymes normalized. His chin numbness was stable.
Discussion: This case illustrates a rare presentation of secondary syphilis mimicking metastatic cancer with NCS and numerous hepatic lesions. Liver involvement in secondary syphilis is common but classically manifests as syphilitic hepatitis. While discrete hepatic lesions have been reported in advanced disease [1-2], few case reports exist on this finding in earlier stages of syphilis . Neurosyphilis is defined by central nervous system involvement; common presentations include aseptic meningitis, ocular- and oto-syphilis, and asymptomatic neurosyphilis. In contrast, NCS represents peripheral nerve involvement. NCS is a rare syndrome that most commonly arises from orodental trauma but is also caused by neoplasm (metastatic breast, prostate, lung, and lymphoma/leukemia), drugs/toxins, autoimmune disease, and infection . Though known infectious causes of NCS include Lyme disease, HIV, and HSV, this apparent case of syphilis causing bilateral mental neuropathy has not previously been reported [4-5].
Conclusions: Syphilis remains a common condition but may present with uncommon clinical symptoms, especially in patients with HIV. Despite the initial concern for metastatic cancer, careful history taking, physical exam, and a high degree of suspicion ultimately led to the correct diagnosis.