Differential Diagnosis for Pus Coming from Pin Holes after Ex-Fix Removal

• Single Most Likely Diagnosis
  • Pin site infection: This is the most common complication following external fixator removal. The presence of pus from the pin holes is a clear indication of an infectious process, likely caused by bacteria that colonized the pin sites during the time the external fixator was in place.
• Other Likely Diagnoses
  • Osteomyelitis: An infection of the bone that could have been introduced through the pin sites. The proximity of the infection to the bone and the fact that the infection is coming from the pin holes make osteomyelitis a plausible diagnosis.
  • Soft tissue infection: While the primary concern is the bone, the soft tissues surrounding the pin sites can also become infected, leading to the production of pus.
• Do Not Miss Diagnoses
  • Chronic osteomyelitis: If the infection has been ongoing and not properly treated, it could lead to chronic osteomyelitis, which is much harder to treat and can lead to significant morbidity.
  • Sepsis: Although less likely, any infection can potentially lead to sepsis if not properly managed, especially in immunocompromised patients or if the infection is caused by a virulent organism.
• Rare Diagnoses
  • Actinomycosis: A rare chronic bacterial infection that can mimic other conditions, including osteomyelitis. It's less common but should be considered if the patient does not respond to typical antibiotic treatments.
  • Mycobacterial infection: Infections caused by mycobacteria, such as those causing tuberculosis, can present with chronic infections and might be considered in endemic areas or in patients with specific risk factors.
  • Fungal infection: Fungal infections, such as those caused by Candida, can occur, especially in immunocompromised patients, and might present with similar symptoms, including pus from the pin sites.