A 40 years female has palpable purpura with rash over buttocks and thighs, pain in abdomen and ahropathy. Likely diagnosis is?

Henoch-Schonlein purpura (HSP) is a subtype of acute LCV, seen more commonly in children and adolescents following an upper respiratory infection. Majority of lesions are found on the lower extremities and buttocks. Systemic manifestations include fever, ahralgias (primarily of the knees and ankles), abdominal pain, gastrointestinal bleeding, and nephritis. DIF examination shows deposits of IgA within dermal blood vessel walls. Renal disease is of concern in adults with HSP.