Henoch-Schönlein Purpura (HSP): This condition is characterized by the deposition of IgA immune complexes, leading to inflammation of small blood vessels. It often presents with purpura, abdominal pain, arthralgias, and renal involvement. Elevated CRP and ESR are common due to the inflammatory nature of the disease.

Systemic Lupus Erythematosus (SLE): SLE is an autoimmune disease that can affect multiple organ systems. It can present with a wide range of symptoms, including purpura, due to vasculitis or thrombocytopenia. Elevated inflammatory markers like CRP and ESR are typical.
Rheumatoid Arthritis (RA): Although RA primarily affects the joints, it can also cause systemic inflammation and, in some cases, vasculitis leading to purpura. Elevated CRP and ESR are common in active RA.
Infectious Endocarditis: This condition, characterized by infection of the heart valves, can lead to embolic phenomena, including purpura. Elevated CRP and ESR are typical due to the chronic infection and inflammation.

Meningococcemia: This is a life-threatening infection caused by Neisseria meningitidis. It can present with purpura fulminans, a severe form of purpura, along with elevated inflammatory markers. Prompt diagnosis and treatment are crucial.
Thrombotic Thrombocytopenic Purpura (TTP): TTP is a disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, renal failure, and neurological symptoms. Purpura can be a presenting feature, and elevated CRP and ESR may be seen due to the underlying inflammation and endothelial damage.
Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): GPA is a form of vasculitis that affects small- and medium-sized vessels. It can present with a wide range of symptoms, including purpura, and is associated with elevated inflammatory markers.

Churg-Strauss Syndrome (Eosinophilic Granulomatosis with Polyangiitis, EGPA): This is a rare form of vasculitis characterized by asthma, eosinophilia, and vasculitis affecting multiple organ systems. Purpura can be a feature, and elevated CRP and ESR are expected due to the inflammatory nature of the disease.
Cryoglobulinemia: This condition involves the presence of cryoglobulins (proteins that precipitate from blood at cold temperatures) and can lead to vasculitis, purpura, and elevated inflammatory markers.
Paroxysmal Nocturnal Hemoglobinuria (PNH): PNH is a rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells, bone marrow failure, and the potential for thrombotic events. Purpura can be a feature, although it is less common.