Differential Diagnosis for IgA Vasculitis

Single Most Likely Diagnosis

• Henoch-Schönlein Purpura (HSP): This is the most likely diagnosis, as IgA vasculitis is a hallmark of HSP, a small-vessel vasculitis characterized by the deposition of IgA immune complexes. It typically presents with palpable purpura, abdominal pain, arthralgias, and renal involvement.

Other Likely Diagnoses

• Infectious Vasculitis: Certain infections can cause vasculitis with IgA deposition, such as streptococcal or staphylococcal infections. The clinical presentation can mimic HSP but is distinguished by the presence of an underlying infection.
• Systemic Lupus Erythematosus (SLE): SLE can present with vasculitis and may have IgA deposits, although it is less common. SLE is characterized by a wide range of autoimmune manifestations, including joint, skin, renal, and neurological involvement.
• Cryoglobulinemic Vasculitis: This condition involves the deposition of cryoglobulins (proteins that precipitate at cold temperatures) and can present with IgA vasculitis. It is often associated with hepatitis C infection and can cause skin, renal, and neurological symptoms.

Do Not Miss Diagnoses

• Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): Although GPA typically involves IgG or IgM antibodies, it can rarely present with IgA vasculitis. GPA is a life-threatening condition characterized by granulomatous inflammation and vasculitis affecting the respiratory tract and kidneys.
• Microscopic Polyangiitis (MPA): MPA is another form of small-vessel vasculitis that can present similarly to IgA vasculitis. It is characterized by the absence of granulomas and can affect various organs, including the kidneys and lungs.
• Goodpasture's Syndrome: This is a rare autoimmune disease characterized by antibodies against the glomerular basement membrane, which can present with renal and pulmonary manifestations. Although it does not typically involve IgA, it is a critical diagnosis not to miss due to its severity.

Rare Diagnoses

• Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome): This condition is characterized by asthma, eosinophilia, and vasculitis. While it can involve IgA deposits, it is rare and distinguished by its association with asthma and eosinophilia.
• IgA Nephropathy with Systemic Involvement: IgA nephropathy (Berger's disease) primarily affects the kidneys but can rarely have systemic manifestations, including vasculitis. It is characterized by the deposition of IgA in the glomeruli and can present with hematuria and renal failure.