Final answer:
A young boy with elevated arm blood pressure and no femoral pulses likely has coarctation of the aorta, a congenital narrowing of the aorta that affects blood circulation.
Step-by-step explanation:
The clinical presentation described suggests that the most likely diagnosis for the young boy with elevated blood pressure in his arm and absence of femoral pulses is coarctation of the aorta. This is a congenital condition where part of the aorta is narrowed, leading to increased pressure before the coarctation and decreased pressure after it. This would explain the high blood pressure reading in the arm and the absence of femoral pulses. Additionally, this condition might require confirmation by echocardiogram or MRI and management by a cardiovascular specialist.