Allergic purpura

This code represents a non-thrombocytopenic purpura characterized by palpable purpuric skin lesions, often accompanied by arthralgia, abdominal pain, and renal involvement. It is an immune-mediated vasculitis, commonly known as Henoch-Schönlein purpura (HSP) or IgA vasculitis, where immune complexes deposit in small blood vessels.

Assign this code for diagnoses of Henoch-Schönlein purpura or IgA vasculitis when documented by a physician. This includes cases presenting with the classic tetrad of rash, arthralgia, abdominal pain, and kidney disease, or any combination thereof, provided thrombocytopenia is ruled out. Documentation should clearly indicate the allergic or immune-mediated nature of the purpura.

• Ensure documentation explicitly states "allergic purpura," "Henoch-Schönlein purpura," or "IgA vasculitis" and confirms a non-thrombocytopenic etiology.
• Do not use this code if the purpura is due to thrombocytopenia; refer to the Excludes1 note for appropriate coding.
• Code any associated manifestations (e.g., nephritis, arthritis, gastrointestinal hemorrhage) separately as secondary diagnoses.