Differential Diagnosis for a 13-year-old Female with Right Sided Ear Infection and Swollen Knot Behind Ear

• Single Most Likely Diagnosis
  • Acute mastoiditis: This condition is a complication of acute otitis media (ear infection) where the infection spreads to the mastoid bone, located behind the ear. The swollen knot behind the ear could be indicative of mastoiditis, especially if the patient has recently had an ear infection.
• Other Likely Diagnoses
  • Lymphadenitis: Inflammation of the lymph nodes, which could be caused by a bacterial or viral infection, including an ear infection. The swollen knot could represent an enlarged lymph node.
  • Periauricular abscess or cellulitis: An abscess or cellulitis (skin infection) around the ear could cause swelling and a knot-like appearance behind the ear, especially if it's related to an ear infection.
  • Otitis externa: An infection of the outer ear canal, which could potentially cause swelling behind the ear if the infection spreads.
• Do Not Miss Diagnoses
  • Malignancy (e.g., lymphoma, rhabdomyosarcoma): Although rare, malignancies can present with lymphadenopathy (swollen lymph nodes) or masses behind the ear. It's crucial to consider these diagnoses to ensure timely treatment if present.
  • Neurological conditions (e.g., acoustic neuroma, meningioma): Certain neurological conditions can cause masses or swelling behind the ear, though they are less likely to be directly associated with an ear infection.
• Rare Diagnoses
  • Mastoid osteoma: A benign bone tumor of the mastoid part of the temporal bone, which could cause a swelling behind the ear but is not typically associated with an ear infection.
  • Cholesteatoma: An abnormal skin growth in the middle ear behind the eardrum, which can be a complication of chronic ear infections. It might cause swelling if it becomes infected or erodes into surrounding bone.