Differential Diagnosis for a 3-year-old Male Child with Fever, Mouth Ulcers, and Ulcer over Hard Palate

• Single most likely diagnosis:
  • Hand, Foot, and Mouth Disease (HFMD): This is a common viral illness in children, characterized by fever, mouth ulcers, and a rash on the hands and feet. The presence of ulcers on the hard palate is also consistent with HFMD, making it the most likely diagnosis given the symptoms.
• Other Likely diagnoses:
  • Herpetic Gingivostomatitis: Caused by the herpes simplex virus, this condition presents with fever, mouth ulcers, and gingivitis. It's a common cause of oral ulcers in children and could explain the symptoms.
  • Aphthous Ulcers: Although less likely to cause fever, aphthous ulcers (canker sores) can occur on the hard palate and are common in children. However, the presence of fever might suggest a more systemic condition.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Infectious Mononucleosis: Caused by Epstein-Barr virus, it can present with fever and oral ulcers, including petechiae on the palate. Although less common in very young children, it's a diagnosis that should not be missed due to its potential complications.
  • Acute Leukemia: Although rare, acute leukemia can present with oral ulcers, fever, and other non-specific symptoms. Given the potential severity of this condition, it's crucial to consider it in the differential diagnosis.
• Rare diagnoses:
  • Autoimmune Disorders (e.g., Pemphigus, Stevens-Johnson Syndrome): These conditions can cause oral ulcers but are rare in children and often present with additional symptoms such as skin lesions.
  • Primary Immunodeficiency Diseases: Certain immunodeficiencies can predispose children to recurrent or severe infections, including those causing oral ulcers. However, these conditions are rare and would typically be associated with a history of recurrent infections.