Rosh Pediatrics Practice Exam 2025 - Free Pediatrics Exam Practice Questions and Study Resource.

The most likely diagnosis for a 12-year-old boy with tonsillar exudate, tender lymphadenopathy, and palatal petechiae is Streptococcal pharyngitis. This condition, commonly caused by group A Streptococcus bacteria, is characterized by the presence of tonsillar exudate (white patches or pus on the tonsils), which is a classic symptom. The tender lymphadenopathy, or swollen and painful lymph nodes, often accompanies this infection as the body mounts an immune response against the bacteria.

Palatal petechiae, which are small red or purple spots on the palate, are a notable clinical feature associated with streptococcal infections. The combination of these symptoms strongly suggests that the underlying cause is a bacterial infection rather than a viral one, which typically would not cause such prominent exudate or petechiae.

While diphtheria can present with tonsillar exudate and lymphadenopathy, it is less common today due to widespread vaccination, and the presentation would generally include a gray membrane rather than exudate. Limierre syndrome is a more severe condition that follows a throat infection and is characterized by septic thrombophlebitis but is not commonly diagnosed based on the initial presentation