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DIAGNOSTIC PATHOLOGY
DIAGNOSTIC PATHOLOGY
PATOLOGIA
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PATOLOGIA
DIAGNOSTICA
PATOLOGIA DIAGNOSTICA
It is the responsibility
of the pathologist to produce an accurate morphologic
diagnosis but, it is the responsibility of the nephrologist
to provide him with an adequate biopsy.
The most important consult a renal pathologist can do, is
call the clinician to discuss the findings with him and
obtain clinical information to make a final diagnosis of
disease.
Es responsabilidad del
Patólogo producir un diagnóstico
morfológico preciso sin embargo, es responsabilidad
del Nefrólogo proveerle una biopsia adecuada.
La consulta mas importante que puede hacer el
Patólogo renal, es llamar al clínico para
discutir los hallazgos con el y obtener información
clínica para hacer un diagnostico final de
enfermedad.
Fig # 1.
Skeletal muscle / Músculo esquelético.
Adipose tissue / Tejido adiposo.
Kidney without glomeruli, unfixed / Riñon sin glomérulos, sin fijar.
Kidney with glomeruli, unfixed. / Riñón con glomérulos, sin fijar.
Kidney with glomeruli, fixed. / Riñón con glomérulos, fijado.
HANDLING THE RENAL BIOPSY:
All biopsies should
be examined at bed side under the lower power of a light
microscope (lower condenser) or a magnifying glass for
adequacy of the sample. Adipose tissue , connective tissue,
skeletal muscle and kidney with or without glomeruli are
readily recognized under these instruments.
A large needle core (>10mm) may
be all medullary kidney and have no glomeruli.
To confirm the adequacy
of a renal biopsy, there is no substitute for the
microscopic examination of the sample at bed
side.
We use epoxy
Histotechnology for High Resolution Light Microscopy (HRLM).
This Light Microscopy (LM) method replaces the traditional
paraffin Histotechnology (PLM) because it allows full
utilization of the resolving power of the light microscope
(0.2 um) and needs no special stains. HRLM is fully
integrated with Transmission Electron Microscopy (TEM). This
is not possible with paraffin Histotechnology.
Immunohistology (IH) is performed by the traditional
methods. In our Laboratories we suggests two cores of needle
biopsies gage 14 (one for HRLM-TEM and one for IH) or three
biopsies gage 18 (two for HRLM-TEM and one for IH).
MANEJO DE LA BIOPSIA
RENAL:
Todas las biopsias
renales deben ser examinadas, al momento de tomarlas usando
el menor aumento del microscopio de luz (comdesador bajo) o
una lupa, para confirmar si son adecuadas. El tejido
adiposo, conectivo, músculo esquelético y
riñón, con o sin glomérulos, son
fácilmente reconocidos bajo estos instrumentos. Un
cilindro obtenido por puncion puede ser largo (>10mm) y
no tener ningun glomerulo por ser riñon medular.
No hay
substituto para el examen microscopico de la biopsia renal
inmediatamente despues de tomarla, para confirmar que es
adecuada.
Nosotros usamos Histotecnología de epoxies para
Microscopía Optica de Alta Resolución (MOAR).
Este método ha reemplazado al método
tradicional de la parafina (PLM), por que permite la
utilización del poder máximo de
resolución del microscopio de luz (0.2 um) y no
necesita coloraciones especiales. MOAR esta totalmente
integrada al estudio por Microscopía
Electrónica de Transmisión (MET). Esto no es
posible con la histotecnología por parafina.
Inmunohistologia (IH) es usada con los métodos
tradicionales. En nuestros laboratorios sugerimos la
obtención de dos biopsias por aguja de punción
# 14(una para MOAR-MET y una para IH). O tres biopsias por
aguja # 18 (dos para MOAR-MET y una para IH).
Fig. # 2.
FContainer with Parafor G fixative for HRLM-TEM studies.
Container with Zeus transport media for IH (FM) studies.
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ALLOTMENT OF TISSUE OBTAINED BY THE RENAL BIOPSY(Fig # 2): Needle cores of fat, skeletal muscle, and connective tissue will fragment and float when placed in the fixative. Renal cores will remain solid and sink. Fat, connective tissue, skeletal muscle, kidney without glomeruli and kidney with glomeruli, are easily recognized under the low power of a microscope, dissecting microscope or a magnifying glass. (Fig #1). DO NOT MINCE THE SAMPLE IN 1mm CUBES. |
DISTRIBUCION DEL TEJIDO OBTENIDO POR LA BIOPSIA RENAL(Fig# 2). Tejido adiposo, músculo esquelético y tejido conectivo se fragmentan y flotan cuando se colocan en el fijador o medio de transporte. El tejido renal se mantiene intacto y se hunde. La naturaleza de todos estos tejidos es fácilmente reconocida en el microscopio de luz o una lupa (Fig# 1). NUNCA FRAGMENTE LA MUESTRA EN CUBOS DE 1 mm. |
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Fig # 2. How to allot
the tissue samples from renal biopsies: |
Fig # 2. Como
distribuir el tejido obtenido por la biopsia
renal: |
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Fig #3: PROBLEMS
CREATED BY MINCING THE SAMPLE |
Fig # 3: PROBLEMAS
CREADOS POR EL PICADO DE LA MUESTRA: |
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ADEQUACY OF THE RENAL BIOPSY: A renal biopsy with 10 glomeruli is usually accepted as an adequate sample to make a morphologic diagnosis. However, for the morphologic evaluation of activity this material represents 1/200, 000th of the total glomeruli (2,000,000). This is a very small sample, especially if one takes in to consideration that most renal diseases have focal or focally accentuated lesions. If only 10% of the glomeruli in the kidneys are involved by a focal process, a biopsy sample with ten glomeruli has a 35% probability of missing the diagnostic lesions. When 25% of the glomeruli are involved there is only a 5% chance of missing the diagnostic lesions. The number of glomeruli in the biopsy is even more crucial for the assessment of the grade (activity) and stage (chronicity) of the process. Hence, a biopsy with 20 to 25 glomeruli is sufficient for this purpose. |
BIOPSIA RENAL ADECUADA: Generalmente se acepta que una biopsia renal con por lo menos 10 glomérulos es adecuada para hacer un diagnostico morfológico. Sin embargo, para la evaluación morfológica de la actividad (GRADO) y de la cronicidad (ESTADIO), se necesitan mas de 20 glomérulos. Una biopsia con 10 glomérulos representa la 1/200.000 ava parte del numero total de glomérulos (2.000.000). Si se reconoce que la mayor parte de las lesiones glomerulares son focales o focalmente acentuadas, una biopsia con 10 glomérulos tiene la probabilidad de no contener lesiones visibles en el 35% de los casos si las lesiones envuelven solamente al 10% de los glomérulos. Si el porcentaje de glomérulos envueltos es del 25%, la probabilidad de no ver las lesiones focales en una biopsia con 10 glomérulos es de solamente el 5%. Por lo tanto, una biopsia adecuada para diagnóstico y evaluación de actividad y cronicidad debe tener mas de 20 glomérulos para tener solamente el 5% de riesgo de no ver lesiones focales . |
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Sampling
problem: Single needle biopsy: Left side normal. Right
side advanced nephrosclerosis. You
could receive either side in a biopsy. |
Sampling problem: Two cores of the same needle biopsy: Left normal. Righ acute rejection. You could receive either side in a biopsy. | ||
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REASON FOR NOT
ACCEPTING RENAL BIOPSIES: |
RAZONES PARA NO ACEPTAR
BIOPSIAS |
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To confirm the adequacy of a renal biopsy, there is no substitute for the microscopic examination of the sample at bed side. |
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References / Referencias: Colwin HL, Schwartz MM, Lewis EJ: The importance of sample size in the interpretation of renal biopsy. Am J Nephrol 8:85-89, 1990. Feinstein AR, Sosin DM, Wells CK: The Will Rogers Phenomenon: stage migration and new diagnostic techniques as a source of misleading survival statistics for survival in cancer. New Engl J Med 312:1604-1608, 1985. Wang HJ, Kjellstrand CM, Cockfield SM and SolezK: On the influence of sample size on the pronostic accuracy and reproducibility of renal transplant biopsy. Nephrol Dial Transplant 13:165-172, 1998. H Regele, B Mougenot, P
Brown, MP Rastaldi, M Leontsini, L Gesualdo, T
Colucci Furness, Peter N. :
Best Practice # 160. Renal Biopsy Specimen. J Clin
Pathol 2000; 53:433-438. |
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Kim D, Kim H, Shin G, Ku S, Ma K, Shin S, Gi H, Lee E, Yim H.: Am J Kidney Dis 1998 Sep;32(3):426-31. A randomized, prospective, comparative study of manual and automated renal biopsies. Department of Nephrology, Ajou University School of Medicine, Suwon, Kyungkido, Korea. kimdohun@madang.ajou.ac.kr A percutaneous renal biopsy can be performed in several ways, including using a spring-loaded biopsy gun. As this form of renal biopsy has become more popular, a controversy has developed regarding tissue adequacy and the incidence of complications. To compare these two aspects in an automated biopsy and a manual biopsy, we studied 166 patients assigned to one of the two renal biopsy methods. In a randomized, prospective manner from June 1994 until February 1997, group 1 (67 patients) received a 14 G Tru-cut needle (Baxter, Deerfield, IL) manual biopsy while group 2 (99 patients) received an 18 G automated gun biopsy. There was no difference in sex, age, hemoglobin level, prothrombin time, partial thromboplastin time, or diastolic and systolic blood pressure prebiopsy in groups I and II. Indications for biopsy were proteinuria (38%), proteinuria accompanied by hematuria (31.3%), acute renal failure (9.6%), lupus nephropathy (9.6%), chronic renal failure (6%), and hematuria only (5.4%). In group I, the number of cores was 1.88 +/- 0.56, the glomeruli obtained were 27.3 +/- 13.8, and the number of glomeruli per core were 15.3 +/- 8.4. In group II, the values were 2.37 +/- 0.88, 20.7 +/- 11.1, and 9.95 +/- 6.9, respectively. These results showed a statistically significant difference (P < 0.05). In all cases, pathological diagnosis was possible. The histology showed IgA nephropathy in 25.9%, minimal change disease in 16.3%, lupus nephritis in 11.4%, membranous glomerulonephropathy in 9.3%, membranoproliferative glomerulonephritis in 5.4%, and others. The incidence of postbiopsy hematoma was marginally greater in group I (22.3% v 11.1%) and the area of perirenal hematoma shown on ultrasound 24 hours postbiopsy was larger in group I, as well (848 +/- 623 mm2 v 338 +/- 260 mm2). Hematocrit levels before and after biopsy showed a significant difference (34.9% +/- 7.9% and 34.0% +/- 7.6%, respectively; P < 0.05) in group I, but no significant difference was observed in group II (35.1% +/- 7.0% and 34.7% +/- 6.9%). Both techniques rendered adequate tissue sampling, but the extent of bleeding was more severe with the manual 14 G Tru-cut needle biopsy.
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I am a little disconcerted by the RPA's (Renal Physicians Association) recent publication "RPA Position on the Optimal Length of Observation After Percutaneous Renal Biopsy" (Clin Nephrol, Vol 56 No.2/2001,p179-180 ). By stating that the optimal period of close observation is 23-24 hours, a national "community" standard is established for our malpractice courts. The paper admits there is little clinical data. Apparently most of the recommendations are derived from Marwah and Korbet's paper (AJKD 1996 vol 28 pp47-52) which evaluated 394 adult kidney biopsies from 1983-1995. 225 bx were performed with 14 ga. Tru-cut needle, 169 bx were done with an automated 14 ga. biopsy needle. Furthermore this was a training institution where most likely the nephrology fellows were learning the technique. Therefore I'm not sure their complication rate and timing results are applicable to current clinical nephrology practice. For example in my practice 3 nephrologists have performed 180 renal biopsies in the past three years using an automated 16 ga. and 18 ga. biopsy needle using ultrasound direction or needle-guidance. No blood transfusions or overnight stays have been necessary. Typically pts are discharged home 5- 8 hours post bx. I think we have a zero complication rate for several reasons: a) nephrologists are in general more ultrasound "savvy" these days, b) the automated biopsy needle is safer and more efficient(requiring less passes/attempts to obtain tissue) c) 16-18 ga needles are safer than the Vim -Silverman or 14 ga. Tru-cut needles and provide plenty of glomeruli for pathologic dx. RPA's mentions a "low -risk" patient and "high risk" patient but does not define these categories. The 23-24 hour observation period recommendation is so arbitrary; it conveniently "fits" into the 23 hour observation status to avoid admission to the hospital. Per Marwah and Korbet's paper "complications were apparent in 98% of patients by 24 hours". So what about the safety of the other 2%. I would have been much more impressed if the RPA panel of experts had just said 1) renal biopsy can cause serious bleeding and death and 2)renal biopsy patients have to be admitted to the hospital for safety. Instead they walk a fine line of balancing economics vs safety of the procedure with their wishy-washy recommendations of 23-24 hour obs. and low and high risk patients. By the way where is their data that ASA and NSAID's should be witheld 10-14 days prior to a renal biopsy? We haven't been witholding Aspirin or NSAIDS 10-14 days prior to bx. We don't check bleeding times either. We do control BP and make sure the coagulation studies and plt ct are OK. I'm not being cavalier ; I would prefer better evidence and support for these recommendations. I pity the poor nephrologist who biopsies a "low risk" patient after all the risks were explained, and sends him home 8 hours later only to have him return later with a complication. The trusting doctor -physician relationship will dissolve once a lawyer shows the patient a document proving that the "optimal" standard of care had not been followed. I am a strong supporter of the RPA . I disagree with this RPA 's position paper. I believe percutaneous renal biopsy to be a safe procedure in my hands. I believe the risks and benefits of this procedure should be thoroughly discussed with the patient. I think each nephrologist should determine the observation period post biopsy in each circumstance. He should not be told by an insurance co. or medicare or an "expert panel" what that "optimal" observation period is. (Sept. 2001). Thanks for listening. Jeffrey Hoggard MD Eastern Nephrology Assoc Greenville, NC |
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