Palpable Purpura Differential Diagnosis
Palpable purpura refers to the presence of purple spots that can be felt on the skin, often indicating inflammation of small blood vessels. The differential diagnosis for palpable purpura can be categorized as follows:
Single Most Likely Diagnosis
- Henoch-Schönlein Purpura (HSP): This is the most common cause of palpable purpura, especially in children. HSP is a form of vasculitis that affects small blood vessels and is characterized by the deposition of IgA immune complexes. It typically presents with palpable purpura, abdominal pain, arthritis, and sometimes renal involvement.
Other Likely Diagnoses
- Leukocytoclastic Vasculitis: This condition is characterized by inflammation of small blood vessels and can present with palpable purpura. It is often associated with infections, medications, or systemic diseases.
- Wegener's Granulomatosis (Granulomatosis with Polyangiitis): A form of vasculitis that affects small to medium-sized blood vessels and can present with palpable purpura, along with respiratory and renal symptoms.
- Microscopic Polyangiitis: Another form of vasculitis that affects small blood vessels and can present with palpable purpura, renal involvement, and sometimes lung symptoms.
Do Not Miss Diagnoses
- Meningococcemia: Although less common, this condition can present with palpable purpura and is life-threatening if not promptly treated. It is caused by Neisseria meningitidis and requires immediate antibiotic therapy.
- Disseminated Intravascular Coagulation (DIC): A condition characterized by widespread clotting and bleeding, which can present with purpura. It is often associated with severe infections, trauma, or malignancy.
- Thrombotic Thrombocytopenic Purpura (TTP): A rare disorder characterized by clotting in small blood vessels, which can present with purpura, along with thrombocytopenia and microangiopathic hemolytic anemia.
Rare Diagnoses
- Churg-Strauss Syndrome (Eosinophilic Granulomatosis with Polyangiitis): A rare form of vasculitis that affects small to medium-sized blood vessels and is associated with asthma and eosinophilia.
- Cryoglobulinemic Vasculitis: A condition characterized by the deposition of cryoglobulins (proteins that precipitate in cold temperatures) in blood vessels, leading to inflammation and palpable purpura.
- Rheumatoid Vasculitis: A rare complication of rheumatoid arthritis, characterized by inflammation of blood vessels and can present with palpable purpura.