Differential Diagnosis for a 9-Year-Old Patient with Lumbar Back Pain

Single Most Likely Diagnosis

• Spondylolisthesis or Spondylolysis: This condition is common in children and adolescents, especially those involved in sports that include repetitive hyperextension of the spine. The patient's symptoms of lumbar back pain exacerbated by hyperextension, radiating pain down the back of the thighs, and numbness/tingling are consistent with this diagnosis. The improvement with Motrin and the plan for physical therapy also align with the management of this condition.

Other Likely Diagnoses

• Musculoskeletal Strain: Given the patient's age and the nature of the pain, a musculoskeletal strain is a plausible diagnosis. The pain pattern and the fact that Motrin helps suggest an inflammatory component, which could be seen in a strain.
• Herniated Disk: Although less common in children, a herniated disk could cause the described symptoms, including radiating pain and numbness/tingling. The patient's symptoms of pain worsening with hyperextension and improving with Motrin could fit this diagnosis.

Do Not Miss Diagnoses

• Spinal Tumor or Malignancy: Although the patient's mother denies signs of systemic illness, fatigue, or weight loss, it's crucial to rule out malignancy due to its severe implications. The lab work ordered is appropriate for this purpose.
• Infectious Processes (e.g., Osteomyelitis, Discitis): These conditions can present with back pain and are important to diagnose early due to their potential for serious complications. The absence of fever or systemic symptoms does not entirely rule out these conditions.
• Cauda Equina Syndrome: This is a medical emergency that can present with back pain, radiating pain, numbness, tingling, and potentially bladder/bowel dysfunction. Although the patient's symptoms do not fully align with cauda equina syndrome, any suspicion warrants immediate further investigation.

Rare Diagnoses

• Scheuermann's Kyphosis: This condition affects the thoracic spine more commonly but can involve the lumbar region, leading to back pain and postural changes. It's less likely given the specific symptoms but could be considered if other diagnoses are ruled out.
• Ehlers-Danlos Syndrome or Other Connective Tissue Disorders: These conditions can lead to musculoskeletal symptoms, including back pain, due to joint hypermobility and tissue fragility. They are less common and would require specific diagnostic criteria to be considered.