<s>[INST] context: Mesangial deposits of IgA Purpura in Henoch Schonlein purpura is due to vasculitis and not thronzbocytopenia Platelet count is either nonnal or elevated. H.S. purpura is characterized by tetrad of PurpuraQ, Ahritis', GlomerulonephritisQ and Abdominal painQ. Skin The hallmark of this disease is rash beginning as pinkish maculopapules that initially blanch on pressure and progress to petechiae or purpura which are characterized clinically as palpable purpura'. The lesion tends to occur in crops'. The lesion occur on the dependent areas of the body such as buttocks'. Joints (80%) Manifests as ahralgia or ahritis in large joints Large joints of lower extremities are involved especially the knees and the ankles Migratory' pattern of joint involvement is common Ahritis is nondeformine in nature Gastrointestinal tract 60% presents with abdominal painQ 33% have evidence of gastrointestinal bleeding' (melena) Abdominal pain is typically colicky' May worsen after angina' (intestinal angina) Can lead to intussussceptionQ. Kidney (40%) Almost always appear after the development of skin manifestation The clinical hallmark of nephritis in HSP is hematuria which is usually microscopic Studies characteristically demonstrate IgA deposition in the mesangium. Diagnosis of H.S. Purpura -Diagnosis is based upon signs and symptoms - Skin biopsy demonstrates leucocytoclastic vasculitis with IgA and C3 deposition. - Renal biopsy may be helpful. [/INST] question: A 8 year old male had non blanching rashes over the shin and swelling of knee joint with haematuria +++ and protein +. Microscopic analysis of his renal biopsy specimen is most likely to show. | options: A: Tubular necrosis B: Visceral podocyte fusion C: Mesangial deposits of IgA D: Basement membrane thickening | answer: C </s>