<prompt> Renal biopsy done for a patient with proteinuria is shown in this PLATE. What is the most probable diagnosis?Renal tuberculosisRenal amyloidosisRenal cell carcinomaCrescentic glomerulonephritis  <response>: ANSWER: B Renal amyloidosisREF: Robbins 8th ed chapter 6See PLATE - Key PLATE - KeyRENAL AMYLOIDOSIS:See amyloid stains in APPENDIX-24 below HISTOLOGYPATHOLOGY MICROBIOLOGY STAINSA Congo red staining of renal amyloidosis: Amyloid an abnormal protein accumulates as extra-cellular deposits, nodular or diffuse, as pink, amorphous material. Initially, the deposits appear in the glomeruli: within the mesangia matrix and along the basement membranes of the capillary loops. The glomerular architecture is almost totally obliterated by the massive accumulation of amyloid arrow heads. Continuous accumulation of the amyloid will compress and obliterate the capillary tuft. With progression, amyloid deposits appear alsoperitubular and within the arteriolar wall, narrowing them Large arrow. Congo red is a special staining, elective for amyloid. Renal involvement gives rise to proteinuria that may be severe enough to cause the nephrotic syndrome. Progressive obliteration of glomeruli in advanced cases ultimately leads to renal failure and uremia. Renal failure is a common cause of deathB Polarized light microscopy of renal amyloidosis showing Apple green birefringence arrowAPPENDIX - 24HistologyPathologyMicrobiology StainsT issuesubstanoeStainCommentAmyloidGross stainingLugols iodine Light microscopyH E, Congo redPolarised lightCongo redMetachromatic stainMethyl violet, crystal violetFluorescent stainThioflavin TNon specific stainPAS, Toludine blue. Aldan blueCaldumcalcificationVon kossa Alizarin Red SFor small quantitiesCalcein Tetracycline labellingBest for bone mineralizationConnective tissueVan Gieson stain Picric Add Acid FuchsinSimplest method of differential staining of Collagen and other Connective TissueTrichome stain Gomori trichrome stain, Lillies trichome Masson trichomeRed keratinmuscleBluegreen bone collagenPink cytoplasmCarcohydrate Glycogen, cellulose etcPeriodic acid-Schiff stainNon specific for glycogenDiastaseSpecific for glycogenBests carmine LipidSudan stainsSudan III, IV, Sudan Back-B, Oil Red 0Oil Red O largely replaced Sudan III and Sudan IVOil Red O is also used in a technique for staining latent fingerprintsOsmium tetra oxideAs a lipid stain, it is useful in scanning electron microscopy SEMLipofuscinSudan Black B MucinMuscarmineMost specific but less usefulPASMost sensitive, For neutral mucopolysaccharidesAlcian blue Bismark brownCan be used with live cellsColloidal iron Micro organismsFungiH EBluePASRedGomori methamine silverMost sensitiveMycobacteriumZ N stainmethodCarbol fuchsinAuramine Rhodamine stainMost sensitive, mixture of Auramine O and Rhodamine B, used in fluorescence microscopySpirochetesWarthin starry silver stain H PyloriWarthin starry silver stainGiemsa stainHE Pneumocystis Cryptococcus cocci diomycetesGomori methamine silver 