Kidney Needle Biopsy: Evaluation for Adequacy



Kidney Needle Biopsy: Evaluation for Adequacy










Renal 16-g cores are typically 1 mm in diameter × 10-20 mm long (these are ˜ 13 mm). Glomeruli are pale imageor congested bulges; red cell casts are brown streaks or dots. (Courtesy C. Swetts, MD.)






The renal biopsy is first examined under low-power magnification to determine the quality of the sample and search for focal lesions. Representative tissue is then allocated for LM, IF, and EM.


SURGICAL/CLINICAL CONSIDERATION


Goal of Consultation



  • Determine if needle biopsy is adequate for a final diagnosis


  • Allocate tissue for special studies



    • Light microscopy (LM)


    • Immunofluorescence (IF)


    • Electron microscopy (EM)


    • Other studies depending on clinical situation



      • Culture for organisms


      • Tissue for molecular studies (e.g., tissue saved in fixatives such as RNAlater for RNA isolation)


Change in Patient Management



  • If specimen is deemed inadequate, additional needle biopsies will be taken


Clinical Setting



  • Medical renal biopsy



    • Generally performed for abnormal renal function or for urinary abnormalities


    • Should include renal cortex with glomeruli


    • Also performed to evaluate renal allografts



      • Allograft biopsies also benefit from IF and sometimes EM studies


      • Some centers perform surveillance (protocol) allograft biopsies at predetermined time points after transplant


      • Surveillance biopsies evaluate for subclinical rejection, viral infection, recurrent disease, etc.


  • Biopsies are usually performed under ultrasound guidance or CT guidance



    • Percutaneous (needle) biopsy



      • Ultrasound-guided, automated gun 16- to 18-gauge needle is usual


      • 3 biopsy passes provide adequate sample (by Banff adequacy criteria) in 84% of cases in native and transplant biopsies


      • Compared to 18-gauge needle biopsies, 16-gauge needle biopsies provide more glomeruli & higher percentage of adequate biopsies with fewer passes


    • Transjugular renal biopsy may be performed in patients at high risk for bleeding (coagulopathy or thrombocytopenia)



      • Typically yields a smaller sample than percutaneous biopsy, but sufficient for diagnosis in > 90% of cases


  • Generally regarded as safe outpatient procedure



    • Hematuria may occur



      • Post-biopsy microscopic hematuria is usual


      • Gross hematuria in ˜ 3.5%


    • Other complications in 1-3% (varies with technique)



      • Higher risk of bleeding with 14-gauge needle biopsy; 16- and 18-gauge needle biopsies have a lower risk of bleeding


      • Perirenal hematoma ˜ 2.5%


      • Bleeding requiring transfusion in 0.9%


      • Hemorrhage requiring nephrectomy in 0.01%


      • Death in 0.02% (2 of 8,971 patients in a metaanalysis)


    • Intrarenal arteriovenous fistulas in ˜ 7% of allograft biopsies



      • Usually resolve


      • No apparent effect on renal function


    • Page kidney (described by Dr. Irwin Page)



      • Most commonly due to trauma, but rare cases occur due to bleeding after kidney biopsy


      • Compression of kidney by accumulation of blood in perinephric or subcapsular space


      • Usually manifests with renin-dependent reactive hypertension due to renal ischemia, occasionally presents with renal insufficiency


SPECIMEN EVALUATION


Gross



  • Biopsies must only be touched by clean forceps



    • Minute amounts of formalin can alter antigenicity of tissue used for immunofluorescence


    • Glutaraldehyde contamination can complicate interpretation by light microscopy and on immunoperoxidase stains



  • Needle biopsies are best examined under stereomicroscopy (dissecting microscope)



    • If dissecting microscope is not available, renal biopsies can be examined using magnifying glass


  • For evaluation of allografts, ≥ 10 glomeruli and 2 arteries must be present (Banff criteria)



    • Glomeruli are pink to red nodules (“raspberries”) in a pale tan background


Allocation of Tissue



  • In majority of cases, tissue is saved for light microscopy, IF, and EM



    • Appropriate allocation of tissue depends on several factors



      • Clinical differential diagnosis


      • Focality of expected disease


      • Amount of tissue available


  • Light microscopy



    • Tissue is fixed in formalin


    • Standard histochemical stains are H&E, PAS, Jonesmethenamine silver, and trichrome


    • Additional stains ordered depending on clinical setting and light microscopy appearance


  • Immunofluorescence



    • Cortex and medulla are placed in Zeus transport solution (Michel solution)


    • Standard immunohistochemical studies are IgA, IgG, IgM, kappa, lambda, C3, C1q, albumin, and fibrin



      • C4d is added for allograft biopsies to evaluate for antibody-mediated rejection


    • If no glomeruli are present in tissue submitted in Zeus medium, IF staining may still be contributory



      • Detection of monoclonal immunoglobulin deposition disease, light chain cast nephropathy, AL or AH amyloidosis, etc.


      • C4d staining of peritubular capillaries for transplant biopsies (C4d may also be performed by immunoperoxidase staining)


    • If no glomeruli present in frozen IF tissue, IF can be performed on pronase-digested paraffin sections



      • Pronase-digested paraffin IF less sensitive than routine IF on frozen tissue


  • Electron microscopy

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Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Kidney Needle Biopsy: Evaluation for Adequacy

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