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What is A 8-year-old male had non-blanching rashes over the shin and swelling of the knee joint with haematuria +++ and protein +. Microscopic analysis of his renal biopsy specimen is most likely to show – and explain in detail?
This child has →

i) Rash             
ii) Arthritis (swelling of knee joint)                       
iii) Haematuria

All these suggest the diagnosis of Henoch Schonlein purpura
HSP is characterized by deposition of IgA in the mesangium.