Differential Diagnosis for Viscous White Discharge in the Ear of a 6-Month-Old Boy

• Single Most Likely Diagnosis
  • Otitis Externa (External Ear Infection): The prescription of neomycin polymyxin B fluocinolone ear drops suggests the doctor suspected an infection. The development of a viscous white discharge after the use of these drops could indicate an external ear infection, possibly exacerbated by the drops or a sign that the infection was present and has progressed.
• Other Likely Diagnoses
  • Middle Ear Infection (Otitis Media): Although the initial concern was with the external ear canal, the presence of a viscous discharge could also suggest a middle ear infection, especially if the eardrum is perforated, allowing discharge to exit through the ear canal.
  • Allergic Reaction to Ear Drops: The introduction of neomycin polymyxin B fluocinolone ear drops could have caused an allergic reaction, leading to increased discharge. Neomycin is known to cause allergic contact dermatitis in some individuals.
  • Eczema (Atopic Dermatitis) of the Ear Canal: Eczema can cause a discharge and is consistent with the initial description of a sensitive spot behind the ear, potentially extending into the ear canal.
• Do Not Miss Diagnoses
  • Mastoiditis: Although rare, mastoiditis is a serious infection of the mastoid bone in the skull, located behind the ear. It can arise from untreated or inadequately treated otitis media and is a medical emergency.
  • Perforated Eardrum with CSF Leak: A perforated eardrum can lead to discharge, and in rare cases, this discharge can be cerebrospinal fluid (CSF), indicating a serious condition that requires immediate medical attention.
• Rare Diagnoses
  • Cholesteatoma: A type of skin cyst located in the middle ear, which can cause discharge. It's more common in adults but can occur in children, especially those with a history of recurrent ear infections.
  • Ear Canal Foreign Body: Although less likely given the age and presentation, a foreign body in the ear canal could cause discharge, especially if it becomes infected or causes irritation.