Differential Diagnosis for the Abscess

The following differential diagnosis is organized into categories to help guide the thought process in identifying the cause of the abscess.

• Single Most Likely Diagnosis
  • Bacterial infection (e.g., Staphylococcus aureus, Streptococcus pyogenes): This is the most common cause of abscesses, often resulting from skin infections or direct inoculation of bacteria into tissues.
• Other Likely Diagnoses
  • Folliculitis or furuncle: Infections of the hair follicle can lead to abscess formation, especially in areas with high sebaceous gland activity.
  • Dental or periodontal infection: Abscesses in the facial or neck region could be related to dental infections.
  • Infected sebaceous cyst: Pre-existing sebaceous cysts can become infected, leading to abscess formation.
  • Foreign body reaction: The presence of a foreign object (e.g., splinter, needle) can cause an abscess.
• Do Not Miss Diagnoses
  • MRSA (Methicillin-resistant Staphylococcus aureus) infection: Given its resistance to common antibiotics, MRSA requires specific treatment and can have severe consequences if not identified.
  • Tuberculosis or other mycobacterial infections: Although less common, these infections can cause abscesses, particularly in immunocompromised individuals or those from endemic areas.
  • Cat-scratch disease (Bartonella henselae): This can cause lymphadenopathy and abscesses, especially after a cat scratch or bite.
  • Actinomycosis: A rare bacterial infection that can cause abscesses, often related to dental procedures, oral surgery, or the use of intrauterine devices (IUDs).
• Rare Diagnoses
  • Echinococcosis (hydatid disease): Caused by the Echinococcus parasite, this condition can lead to cystic abscesses, particularly in individuals from endemic areas.
  • Amebic liver abscess: Caused by Entamoeba histolytica, this condition is rare but can occur in travelers to or immigrants from endemic areas.
  • Cryptococcal infection: In immunocompromised patients, Cryptococcus neoformans can cause abscesses, particularly in the central nervous system but also in other parts of the body.
  • Nocardiosis: An infection caused by Nocardia species, which can lead to abscesses in immunocompromised individuals or those with chronic lung disease.