Differential Diagnosis for Patient with Suspected Thorn in Middle Finger

• Single most likely diagnosis:
  • Paronychia or cellulitis due to a thorn prick: This is the most likely diagnosis given the patient's symptoms of redness, swelling, and throbbing pain in the finger after thinking they have a thorn in the joint. The body's reaction to a foreign object like a thorn can cause infection, leading to these symptoms.
• Other Likely diagnoses:
  • Infectious tenosynovitis: This is an infection of the tendon sheath, which could be caused by a puncture wound from a thorn. Symptoms include pain, swelling, and difficulty moving the finger.
  • Septic arthritis: Although less common, if the thorn penetrated the joint, it could introduce bacteria, leading to septic arthritis, characterized by severe pain, swelling, and decreased range of motion.
  • Foreign body reaction: The body's immune response to a foreign object like a thorn can cause inflammation, leading to symptoms similar to those described.
• Do Not Miss diagnoses:
  • Osteomyelitis: A bone infection that could result from a deep puncture wound. It's crucial to identify and treat promptly to prevent long-term damage.
  • Gas gangrene: A severe, potentially life-threatening condition caused by Clostridium perfringens infection, which could be introduced through a puncture wound. Early recognition and treatment are critical.
• Rare diagnoses:
  • Herpetic whitlow: A viral infection of the finger caused by herpes simplex virus, leading to pain, swelling, and vesicles. It's less likely but should be considered in the differential diagnosis.
  • Erysipelas: A type of skin infection that can cause redness, swelling, and pain, typically affecting the upper dermis. It's less common in this context but could be a consideration.