Differential Diagnosis for a 3-month-old with Post-auricular and Cervical Lymphadenopathy
Single Most Likely Diagnosis
- Viral upper respiratory infection (URI) with reactive lymphadenopathy: This is the most likely diagnosis given the context of a current URI. The post-auricular and cervical lymph nodes are likely reacting to the viral infection, which is a common and self-limiting condition in infants.
Other Likely Diagnoses
- Cat scratch disease: Although less common, cat scratch disease can cause lymphadenopathy, especially in the cervical and post-auricular regions, if the scratch is near these areas. The presence of a URI might be coincidental.
- Tuberculosis (TB): TB can cause lymphadenopathy in any location, including the post-auricular and cervical regions. However, it would be less likely without known exposure or other systemic symptoms.
- Congenital infections (e.g., toxoplasmosis, rubella, cytomegalovirus): These infections can cause lymphadenopathy among other symptoms, but they are typically identified at birth or shortly after, often with other systemic findings.
Do Not Miss Diagnoses
- Malignancies (e.g., leukemia, lymphoma): Although rare in infants, malignancies can cause lymphadenopathy. It's crucial to consider these diagnoses to ensure timely and appropriate treatment.
- HIV infection: HIV can cause persistent generalized lymphadenopathy, and early diagnosis is critical for the management and prognosis of the disease.
- Kawasaki disease: This condition can cause lymphadenopathy, especially cervical, along with fever, rash, and other symptoms. It's a do-not-miss diagnosis due to the risk of cardiac complications if not treated promptly.
Rare Diagnoses
- Castleman disease: A rare disorder that can cause lymphadenopathy, often with systemic symptoms. It's more commonly diagnosed in older children and adults.
- Lymphatic malformations: Abnormal formations of the lymphatic system can cause lymphadenopathy, but these are typically identified at birth or during infancy with other characteristic findings.
- Autoimmune lymphoproliferative syndrome (ALPS): A rare genetic disorder that affects the immune system, leading to lymphadenopathy and other symptoms. It's a diagnosis of exclusion and typically presents with more systemic and recurrent infections.