Differential Diagnosis for the 11-year-old boy with knee and ankle pain
- Single most likely diagnosis:
- A) Autoimmune disorder: The patient's symptoms of moderate pain in the knees and ankles, along with mild swelling, warmth, and tenderness to palpation, are consistent with juvenile idiopathic arthritis (JIA), a common autoimmune disorder in children. The absence of abnormalities on X-rays and the presence of full range of motion also support this diagnosis.
- Other Likely diagnoses:
- D) Previous trauma: Although the patient had previous sprains, the fact that the pain has persisted for a year and is affecting multiple joints suggests that the trauma may not be the sole cause of his symptoms.
- E) Viral infection: A viral infection could cause polyarticular pain and swelling, but the chronic nature of the patient's symptoms makes this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- B) Bacterial infection: Septic arthritis is a medical emergency that requires prompt diagnosis and treatment. Although the patient's symptoms are chronic, it is essential to consider this possibility, especially if the patient's condition worsens or if he develops systemic symptoms such as fever.
- C) Metabolic bone disease: Conditions like rickets or osteomalacia can cause bone pain and weakness, but they are less common in children and would typically be associated with other symptoms such as bowed legs or muscle weakness.
- Rare diagnoses:
- Seronegative spondyloarthropathies: Conditions like ankylosing spondylitis or psoriatic arthritis are rare in children and would typically be associated with other symptoms such as back pain or skin rashes.
- Lyme disease: Although Lyme disease can cause arthritis, it is less common in children and would typically be associated with other symptoms such as a rash or fever.