Differential Diagnosis

• Single most likely diagnosis
  • Paronychia: This is an infection of the skin around the nail, which can cause pus to form. The fact that pus came out of the finger suggests a localized infection, and paronychia is a common cause of such infections.
• Other Likely diagnoses
  • Felon: A felon is an infection of the fingertip pad, which can also cause pus to form. The fact that no more pus has formed could suggest that the infection is resolving or is a small, localized infection.
  • Herpetic whitlow: This is a viral infection of the finger caused by the herpes simplex virus, which can cause pus-like lesions to form. However, these lesions are typically smaller and more painful than bacterial infections.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Osteomyelitis: This is an infection of the bone, which can occur if a skin infection spreads deeper into the tissue. While less likely, osteomyelitis can be serious and even life-threatening if not treated promptly.
  • Septic arthritis: If the infection spreads to the joint, it can cause septic arthritis, which is a serious and potentially life-threatening condition.
  • Tenosynovitis: This is an infection of the tendon sheath, which can cause severe pain and swelling. If left untreated, it can lead to serious complications, including tendon rupture.
• Rare diagnoses
  • Erysipeloid: This is a rare bacterial infection that typically affects the hands and can cause pus-like lesions to form. It is usually associated with exposure to infected animals or contaminated animal products.
  • Sporotrichosis: This is a rare fungal infection that can cause skin lesions, including pus-like lesions, typically after exposure to contaminated soil or plants.