Differential Diagnosis for a 4-year-old with Fever, Cervical Lymphadenopathy, Cough, Muscle Aches, and Raised CK 3600

• Single Most Likely Diagnosis
  • Infectious Mononucleosis (IMN) caused by Epstein-Barr Virus (EBV): Although more common in adolescents, EBV can infect children as young as 4, presenting with fever, lymphadenopathy, and sometimes cough. The raised CK could be due to muscle involvement, though it's less common. However, the combination of symptoms, especially the lymphadenopathy, makes this a strong consideration.
• Other Likely Diagnoses
  • Influenza: Can cause fever, cough, muscle aches, and occasionally lymphadenopathy. The raised CK could be due to myositis associated with influenza.
  • Respiratory Syncytial Virus (RSV) Infection: Though more commonly associated with lower respiratory tract infections in young children, RSV can cause a range of symptoms including fever, cough, and muscle aches. Lymphadenopathy is less common but can occur.
  • Adenovirus Infection: Adenoviruses can cause a variety of clinical syndromes including pharyngoconjunctival fever, which might present with fever, cough, lymphadenopathy, and elevated CK due to muscle involvement.
• Do Not Miss Diagnoses
  • Lymphoma: Although rare in children, lymphoma (such as Hodgkin lymphoma or non-Hodgkin lymphoma) can present with lymphadenopathy, fever, and systemic symptoms like muscle aches. It's crucial to consider this diagnosis to ensure timely and appropriate treatment.
  • Tuberculosis (TB): Can cause chronic fever, cough, lymphadenopathy, and systemic symptoms. TB is a critical diagnosis not to miss due to its implications for public health and the need for specific treatment.
  • Leukemia: Acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML) can present with nonspecific symptoms such as fever, fatigue, and lymphadenopathy. The elevated CK might be seen in cases with significant tissue infiltration or associated hemophagocytic lymphohistiocytosis.
• Rare Diagnoses
  • Dermatomyositis: An autoimmune condition characterized by muscle weakness and skin rash. While rare in children, it could explain the elevated CK and muscle aches, though lymphadenopathy is less commonly a presenting feature.
  • Juvenile Idiopathic Arthritis (JIA): Systemic JIA can present with fever, lymphadenopathy, and systemic symptoms including muscle aches. Elevated CK might be seen due to muscle involvement, though it's not a common finding.
  • Toxoplasmosis: In immunocompetent children, toxoplasmosis can cause lymphadenopathy, fever, and sometimes muscle aches, though it's less common and typically associated with exposure to cats or undercooked meat.