Differential Diagnosis for 56-year-old Male with Left Ear Infection

• Single most likely diagnosis:
  • Cellulitis: Given the patient's history of a pimple-like lesion that was squeezed, leading to continuous oozing, increased redness, and no systemic symptoms like fever, cellulitis is the most likely diagnosis. The absence of pain surrounding the ear and the denial of difficulty swallowing or breathing problems also supports this diagnosis, as cellulitis typically presents with localized signs of infection without severe systemic involvement.
• Other Likely diagnoses:
  • Furuncle or Carbuncle: These are infections of the hair follicle that can present with a painful, swollen lesion, which might fit the initial description of the pimple-like lesion. The squeezing of the lesion could have led to the spread of infection, causing the observed symptoms.
  • Impetigo: A highly contagious skin infection that can cause red sores, oozing, and crusting, which aligns with the patient's symptoms of continuous oozing and increased redness.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Necrotizing Fasciitis: Although less likely, this is a severe infection that can quickly spread and cause significant morbidity and mortality. The absence of severe pain, fever, and systemic symptoms makes it less likely, but it cannot be entirely ruled out without careful examination and possibly imaging.
  • Mastoiditis: An infection of the mastoid bone in the skull, located behind the ear. It's a complication of untreated or inadequately treated otitis media. The patient denies ear pain, but mastoiditis can sometimes present with swelling behind the ear and should be considered, especially if there's any suspicion of middle ear involvement.
• Rare diagnoses:
  • Erysipelas: A type of skin infection that involves the upper dermis, typically caused by beta-hemolytic group A Streptococcus. It presents with well-demarcated, shiny, red lesions and can be accompanied by systemic symptoms like fever, which the patient does not have.
  • Perichondritis: An infection of the tissue surrounding the cartilage of the ear, which can cause redness, swelling, and sometimes a discharge. It's less likely given the description of the lesion being behind the ear rather than on the ear itself, but it should be considered in the differential diagnosis of ear infections.