Differential Diagnosis for Bilateral Knee Pain in a 5-Year-Old Female
Single Most Likely Diagnosis
- Juvenile Idiopathic Arthritis (JIA): Given the chronic nature of the knee pain, worsening at night, and the fact that it's bilateral, JIA is a strong consideration. The negative inflammatory markers (ANA, RF, ESR, CRP) do not rule out JIA, as some forms, like oligoarticular JIA, can have normal inflammatory markers.
Other Likely Diagnoses
- Growing Pains: Although typically more common in the legs rather than specifically in the knees, growing pains are a consideration in children around this age and can cause nighttime pain.
- Osgood-Schlatter Disease: This condition causes knee pain in children, particularly during growth spurts, and is related to inflammation of the patellar tendon. It's more common in one knee but can be bilateral.
- Patellofemoral Pain Syndrome: This condition, also known as runner's knee, can cause knee pain, especially when going up or down stairs, jumping, or after sitting for a long time. It's less likely to cause nighttime waking but is a possibility.
Do Not Miss Diagnoses
- Malignancy (e.g., Leukemia, Bone Tumors): Although rare, malignancies such as leukemia or bone tumors (like osteosarcoma) can present with bone or joint pain, especially if worsening at night. The absence of systemic symptoms or abnormal lab tests does not rule out these conditions entirely.
- Infection (e.g., Septic Arthritis, Osteomyelitis): Infections within the joint or bone can cause severe pain, especially at night, and are medical emergencies. Negative inflammatory markers might not always be elevated in the early stages or in partially treated cases.
- Neuropathic Pain: Conditions affecting the nerves, such as neuropathies, can cause pain that worsens at night.
Rare Diagnoses
- Chronic Recurrent Multifocal Osteomyelitis (CRMO): A rare condition characterized by recurring episodes of bone pain and inflammation, often without an infectious cause.
- Skeletal Dysplasias: Various genetic disorders affecting bone growth and development, which can lead to chronic pain and other skeletal abnormalities.
- Hypertrophic Osteoarthropathy: A rare condition characterized by clubbing of the fingers and toes, joint pain, and new bone formation, often associated with underlying diseases.