# Calvarial Syphilitic Osteomyelitis as a Rare Manifestation of Secondary Syphilis in an Immunocompetent Patient: A Rare Diagnostic Challenge

## TL;DR

A rare case of syphilitic osteomyelitis in the skull of an immunocompetent man is reported, highlighting the importance of considering syphilis in unusual cranial symptoms.

## Contribution

This case report presents a rare manifestation of secondary syphilis as calvarial osteomyelitis in an HIV-negative, immunocompetent patient.

## Key findings

- A 27-year-old male with secondary syphilis presented with calvarial lesions and frontal scalp tenderness.
- MRI was crucial in diagnosing syphilitic osteomyelitis despite normal cerebrospinal fluid findings.
- Treatment with ceftriaxone resolved symptoms and improved radiologic findings.

## Abstract

Syphilitic osteomyelitis of the skull is a rare manifestation of syphilis, typically associated with tertiary or congenital stages, and is exceptionally uncommon during secondary syphilis. We report the case of a 27-year-old immunocompetent, HIV-negative male who presented with persistent headaches and localized frontal scalp tenderness. Magnetic resonance imaging (MRI) revealed two calvarial lesions with adjacent soft tissue and meningeal enhancement. Serological testing confirmed secondary syphilis, while other sexually transmitted infections, including HIV, hepatitis B/C, Neisseria gonorrhoeae, and Chlamydia trachomatis, were excluded. Despite normal cerebrospinal fluid (CSF) findings, Venereal Disease Research Laboratory (VDRL) testing and HIV polymerase chain reaction (PCR) assays on CSF were not performed due to financial limitations. The patient was treated with a 14-day course of ceftriaxone, leading to complete symptom resolution and radiologic improvement. This case highlights the importance of including syphilitic osteomyelitis in the differential diagnosis of atypical cranial lesions, particularly in at-risk patients. It emphasizes the diagnostic value of MRI in such presentations.