Differential Diagnosis

Given the consideration of Still's disease and Churg-Strauss syndrome, the differential diagnosis can be organized into the following categories:

• Single most likely diagnosis:
  • Rheumatoid Arthritis (RA): This is a common autoimmune disorder that can present with similar symptoms to Still's disease, including joint pain and inflammation. It's a likely consideration due to its prevalence and the overlap in symptoms.
• Other Likely diagnoses:
  • Systemic Lupus Erythematosus (SLE): An autoimmune disease that can affect various parts of the body, including the skin, joints, kidneys, brain, and other organs. Its wide range of symptoms can mimic those of Still's disease and Churg-Strauss syndrome.
  • Polyarteritis Nodosa (PAN): A condition characterized by the swelling of the blood vessels, which can lead to organ damage. It shares some clinical features with Churg-Strauss syndrome, such as vasculitis.
  • Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): An autoimmune disorder that causes blood vessel inflammation, which can affect various organs. Like Churg-Strauss syndrome, it involves vasculitis and can present with similar symptoms.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Infectious Endocarditis: Although less likely, this condition can present with systemic symptoms and would be catastrophic if not promptly diagnosed and treated.
  • Lymphoma: Certain types of lymphoma can mimic autoimmune diseases in their presentation. Missing this diagnosis could lead to significant morbidity and mortality.
• Rare diagnoses:
  • Relapsing Polychondritis: A rare autoimmune disorder that involves the cartilage and can present with a variety of systemic symptoms, including those similar to Still's disease and Churg-Strauss syndrome.
  • Eosinophilia-Myalgia Syndrome: A rare condition characterized by elevated eosinophil counts and muscle pain, which could be considered in the differential for Churg-Strauss syndrome due to the eosinophilic component.

Each of these diagnoses has been included based on the potential for overlapping clinical presentations with Still's disease and Churg-Strauss syndrome, emphasizing the importance of a thorough diagnostic workup to accurately determine the underlying condition.