Differential Diagnosis for a 6-year-old Female with Upper Arm Tenderness and Normal X-ray
- Single Most Likely Diagnosis
- Muscle Strain: This is a common injury in children, especially if they have been engaging in physical activities. The normal X-ray helps to rule out fractures, making muscle strain a plausible diagnosis due to overuse or minor trauma.
- Other Likely Diagnoses
- Overuse Injury: Similar to muscle strain, overuse injuries such as medial epicondylitis (in younger athletes who throw) or other repetitive strain injuries could cause upper arm tenderness without showing up on an X-ray.
- Viral Myositis: Viral infections can cause muscle inflammation (myositis), leading to pain and tenderness. This condition might not have specific findings on an X-ray.
- Do Not Miss Diagnoses
- Osteomyelitis: Although less common and the X-ray is normal, osteomyelitis (bone infection) can present with pain and tenderness. Early X-rays might not show changes, making clinical suspicion crucial.
- Child Abuse: It's essential to consider non-accidental injury, especially if the history does not match the injury or if there are other suspicious findings.
- Bone Tumor: While rare, a bone tumor could present with localized pain and tenderness. Early X-rays might not always detect these, especially if they are small or in early stages.
- Rare Diagnoses
- Radial Neck Fracture with Normal X-ray: Some fractures, especially if they are non-displaced or occur in specific areas like the radial neck, might not be visible on initial X-rays.
- Reflex Sympathetic Dystrophy (RSD): Now more commonly referred to as Complex Regional Pain Syndrome (CRPS), this condition can cause severe pain and tenderness out of proportion to the injury. It's rare in children but should be considered if other diagnoses are ruled out.
- Inflammatory Conditions: Conditions like juvenile idiopathic arthritis can cause arm pain and tenderness, though they typically present with other systemic or localized signs of inflammation.