PAS x40 - RCPA

High power examination of H&E stains:• tubules– confirm the nature of any casts(scattered hyaline casts are normal but “hard” casts, cellular casts, redcell casts and haem casts are not)– distinguish proximal and distal tubules byo luminal size (smaller in proximal tubules)o brush border (present only in proximal tubular cellso nuclear morphology (proximal tubular cell nuclei are larger and havesmall nucleoli)ocytoplasmic granularity (prominent in proximal tubules)– check that the brush border in proximal tubules is intact– if there are cytoplasmic vacuoles, assess their size and distribution– mitoses are very rare in normal renal tubules• interstitium– determine the types of cells presento normal interstitium has scant fibroblasts, lymphocytes and macrophageso neutrophils, plasma cells and lymphoid follicles are always abnormalo foamy macrophages are found in heavy/prolonged proteinuriao sometimes the kidney is infiltrated by carcinoma, lymphoma, leukaemiaor even sarcoma– consider whether amyloid or other additional stains are required