Differential Diagnosis

• Single most likely diagnosis
  • Infectious mononucleosis: This diagnosis is the most likely due to the combination of symptoms such as severe sore throat, fever, lymphadenopathy, splenomegaly, exudative pharyngitis, and tonsillitis, which are classic for infectious mononucleosis caused by Epstein-Barr virus (EBV). The patient's age and social history as a college student also increase the likelihood of this diagnosis, as EBV infection is common in this demographic.
• Other Likely diagnoses
  • Streptococcal pharyngitis: This condition could explain the sore throat, fever, and exudative pharyngitis. However, the presence of lymphadenopathy, splenomegaly, and the overall clinical picture makes infectious mononucleosis more likely.
  • Cytomegalovirus infection: CMV can cause a mononucleosis-like syndrome, which might include fever, sore throat, and lymphadenopathy. However, splenomegaly and the specific combination of symptoms presented are more characteristic of EBV infection.
• Do Not Miss
  • Gonococcal pharyngitis: Although less likely given the overall clinical picture, gonococcal pharyngitis is a critical diagnosis not to miss due to its potential for severe consequences if untreated, including dissemination and resistance. The presence of exudative pharyngitis could be a clue, but other symptoms like lymphadenopathy and splenomegaly are not typical.
• Rare diagnoses
  • Varicella: Varicella (chickenpox) could cause fever and malaise, but the presence of splenomegaly, lymphadenopathy, and the specific nature of the pharyngitis make it less likely. Varicella typically presents with a characteristic rash, which is not mentioned in the scenario.
  • Other rare infections: There are other less common viral and bacterial infections that could present with some of these symptoms, but they are less likely given the specific combination of findings and the patient's demographic.