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Differential Diagnosis for Fever, Reactive Lymphadenopathy, and Intermittent Petechial Rash

Single Most Likely Diagnosis

  • Infectious Mononucleosis (Mono): Caused by Epstein-Barr virus (EBV), this condition classically presents with fever, lymphadenopathy, and sometimes a rash, which can be petechial, especially if the patient is taking ampicillin.

Other Likely Diagnoses

  • Acute Viral Hemorrhagic Fever: Certain viral hemorrhagic fevers (e.g., Dengue fever) can present with fever, lymphadenopathy, and a petechial rash due to thrombocytopenia and vascular damage.
  • Infective Endocarditis: Although more commonly associated with heart valve abnormalities, infective endocarditis can cause fever, lymphadenopathy, and petechial rash due to septic emboli and immune complex deposition.
  • Systemic Lupus Erythematosus (SLE): SLE can present with a wide range of symptoms including fever, lymphadenopathy, and a petechial rash, particularly in the context of a vasculitic flare.

Do Not Miss Diagnoses

  • Meningococcemia: A life-threatening condition caused by Neisseria meningitidis, characterized by fever, rash (which can be petechial and progress to purpura), and lymphadenopathy. Prompt recognition and treatment are crucial.
  • Leukemia/Lymphoma: Certain types of leukemia or lymphoma can present with systemic symptoms like fever, lymphadenopathy, and a petechial rash due to bone marrow infiltration and thrombocytopenia.
  • Disseminated Tuberculosis: Although less common, disseminated TB can cause fever, lymphadenopathy, and a variety of skin manifestations, including a petechial rash, especially in immunocompromised patients.

Rare Diagnoses

  • Kawasaki Disease: An acute febrile illness of childhood that presents with fever, lymphadenopathy, rash, and desquamation of the hands and feet. The rash can sometimes appear petechial.
  • Ehrlichiosis/Anaplasmosis: Tick-borne illnesses caused by Ehrlichia or Anaplasma species, which can present with fever, lymphadenopathy, and a petechial rash, although this is less common.
  • Relapsing Fever: Caused by Borrelia species, this condition is characterized by recurring episodes of fever, which can be accompanied by lymphadenopathy and a petechial rash in some cases.

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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