Differential Diagnosis

The patient's symptoms of diminished radial pulse in the left arm, different blood pressures in the arms, regular sinus rhythm with left ventricular hypertrophy, and rib notching on chest X-ray suggest a vascular or cardiac condition. Here is a differential diagnosis organized into categories:

• Single Most Likely Diagnosis

  • Coarctation of the Aorta: This condition is characterized by a narrowing of the aortic isthmus, which can lead to decreased blood flow to the lower body and increased blood pressure in the upper body. The presence of rib notching on chest X-ray, which is caused by enlarged intercostal arteries that help bypass the narrowed aorta, strongly supports this diagnosis. Left ventricular hypertrophy is also a common finding due to the increased afterload on the left ventricle.

• Other Likely Diagnoses

  • Aortic Dissection or Aortic Aneurysm: Although less common in a 12-year-old, these conditions could potentially cause differential blood pressures between arms and diminished pulses. However, they would more typically present with acute symptoms such as severe pain.
  • Subclavian Artery Stenosis or Occlusion: This could cause a diminished radial pulse in the affected arm and differential blood pressures. However, it might not fully explain the left ventricular hypertrophy or rib notching unless it was part of a larger vascular disease process.

• Do Not Miss Diagnoses

  • Takayasu Arteritis: This is a large vessel vasculitis that can cause stenosis or occlusion of major arteries, including the aorta and its branches. It's a rare condition but can be severe and requires prompt treatment. The presence of systemic symptoms such as fever, arthralgias, or elevated inflammatory markers would increase suspicion.
  • Neurofibromatosis Type 1 (NF1) with Vascular Involvement: NF1 can cause vascular abnormalities, including stenosis or occlusion of major arteries. Although less common, it's a critical diagnosis not to miss due to its implications for management and screening.

• Rare Diagnoses

  • Williams Syndrome: This genetic disorder can include supravalvular aortic stenosis, which might present with similar symptoms. However, it typically includes other distinctive features such as elfin facies, developmental delays, and friendly demeanor.
  • Pseudoxanthoma Elasticum (PXE): A genetic disorder affecting elastic fibers in the body, which can lead to vascular complications. It's rare and would typically present with other systemic manifestations such as skin and eye abnormalities.
  • Midaortic Syndrome: A rare condition characterized by stenosis of the abdominal aorta. It could potentially cause differential blood pressures and diminished lower limb pulses but might not fully explain the upper limb findings without additional vascular involvement.

Each of these diagnoses has implications for management and prognosis, highlighting the importance of a thorough diagnostic evaluation.