PATH610-Sheppard

KidneySierra Sheppard

PATH 610

Learning ObjectivesAfter attending a lecture and studying the assigned materials, the student will:1. Identify the basic anatomic structures and location of the

kidneys in the body.2. Interpret the importance of the anatomic features of the

ureters.3. Conclude the appropriate type of neoplasm based off a gross

description.4. Evaluate the correct stage of a tumor based on the CAP

protocol and staging information provided.5. Recall the margins of kidney specimens discussed.6. Select the correct CPT code for each specimen reviewed.7. Recommend the correct sections to take to demonstrate the

proper representation of tumor to kidney parenchyma in all specimens discussed.

Kidney OverviewO Produce urine that is

conveyed by the ureters to the urinary bladder in the pelvis

O Located in the retroperitoneal cavity on the posterior abdominal wall

O Remove excess water, salts and wastes of protein metabolism while returning nutrients and chemicals to the blood

Kidney StructureO Red-brown, approximately 10cm long, 5cm wide, and

2.5cm thickO Encapsulated by a layer of connective tissue called

Gerota’s fasciaO Vessels, nerves and structures that drain urine from the

kidney enter and exit the renal sinus through the renal hilum

O Renal sinus is occupied by the renal pelvis, calyces, vessels, nerves, and fat

O Apex of the renal pelvis is continuous with the ureterO Renal pelvis receives two or three major calyces, each of

which divide into two or three minor calycesO Each minor calyx is indented by a renal papilla, the apex

of the renal pyramid, from which urine is excreted

Kidney Structure

Kidney StructureO The renal cortex is the outer portion of the kidney

between the renal capsule and the renal medullaO It forms a continuous smooth outer zone with a

number of projections called cortical columns that extend down between the renal pyramids

O It includes the renal corpuscles and the renal tubulesO Exception: loop of Henle – extends into the renal

medullaO The renal medulla is the innermost part of the

kidneyO Split into renal pyramids

NephronsO The nephron is the basic structural

and functional unit of the kidneyO Each nephron is composed of an

initial filtering component (the renal corpuscle) and a tubule specialized for reabsorption and secretion (the renal tubule)

Renal CorpuscleO Renal corpuscle is composed of a glomerulus

and the Bowman’s capsuleO The glomerulus is a capillary network that

receives its blood supply from an afferent arteriole

O The glomerular blood pressure provides the driving force for water and solutes to be filtered out of the blood into Bowman’s capsule

O The remainder of the blood passes into the efferent arteriole

Renal TubuleO The filtrate moves through the

glomerulus, to the renal tubule which consists of:O Proximal convoluted tubuleO Loop of HenleO Distal convoluted tubule

O From the distal convoluted tubule, the filtrate continues to the collecting tubule and finally to the ureter and urinary bladder

UretersO The ureters are muscular ducts that carry urine

from the kidneys to the urinary bladderO Run inferiorly from the apices of the renal pelves

at the hila of the kidneysO Demonstrate relative constrictions in three places:

O At the junction of ureters and renal pelvesO Where the ureters cross the brim of the pelvic inletO During their passage through the wall of the urinary

bladderO These constricted areas are potential sites of

obstruction by ureteric stones (calculi)

Suprarenal GlandsO Also called adrenal glandsO Located between the superomedial aspects of the

kidneys and the diaphragmO Surrounded by connective tissue containing

considerable perinephric fatO Each gland has a hilum, where the veins and

lymphatic vessels exit the glandO Arteries and nerves enter the glands at multiple

sitesO Consist of two parts:

O Suprarenal cortexO Suprarenal medulla

Benign Kidney Neoplasms

O Renal Papillary AdenomaO Small discrete adenomas arising from renal

tubular epithelium found commonly at autopsy

O AngiomyolipomaO Consisting of vessels, smooth muscle and fat

originating from perivascular epithelioid cellsO Angiomyolipomas are present in 25% to 50%

of patients with tuberous sclerosisO Oncocytoma

Malignant Kidney Neoplasms

O Renal Cell CarcinomaO Clear Cell Carcinoma

O Most common type, accounting for 70% to 80% of renal cell cancers

O Bright yellow-gray-white spherical masses of variable size that distort the renal outline

O Commonly large areas of gray-white necrosis and foci of hemorrhagic discoloration

O Growth pattern varies from solid to trabecular or tubular

O Made up of cells with clear or granular cytoplasm and are nonpapillary


O Renal Cell CarcinomaO Papillary Carcinoma

O 10-15% of renal cancersO Characterized by a papillary growth patternO Can be multifocal and bilateralO Typically hemorrhagic and cystic, especially

when largeO Chromophobe Carcinoma

O 5% of renal cell cancersO Made up of pale eosinophilic cells, often with a

perinuclear halo


O Xp11 Translocation CarcinomaO Genetically distinct

subtype of renal cell carcinoma

O Collecting Duct (Bellini Duct) CarcinomaO 1% or less of renal

epithelial neoplasmsO Shows irregular

channels lined by a hobnail pattern

CAP Staging of Kidney Tumors

O pT1: Tumor 7cm or less in greatest dimension, limited to the kidneyO pT1a: Tumor 4cm or less in greatest dimension,

limited to the kidneyO pT1b: Tumor more than 4cm but not more than

7cm in greatest dimension, limited to kidneyO pT2: Tumor more than 7cm in greatest

dimension, limited to the kidneyO pT2a: Tumor more than 7cm but less than or equal

to 10cm in greatest dimension, limited to the kidney

O pT2b: Tumor more than 10cm, limited to the kidney

CAP Staging of Kidney Tumors

O pT3: Tumor extends into major veins or perinephric tissues but not into the ipsilateral adrenal gland and not beyond Gerota’s fasciaO pT3a: Tumor grossly extends into the renal vein or its

segmental (muscle containing) branches, or tumor invades perirenal and/or renal sinus fat but not beyond Gerota’s fascia

O pT3b: Tumor grossly extends into the vena cava below the diaphragm

O pT3c: Tumor grossly extends into vena cava above diaphragm or invades the wall of the vena cava

O pT4: Tumor invades beyond Gerota’s fascia (including contiguous extension into the ipsilateral adrenal gland)

Kidney BiopsiesO Typically submitted for non-neoplastic disease

O Electron microscopy and immunofluorescenceO Small specimens should be properly oriented

O Glomeruli should be included in tissue submittedO Distinguish cortex from medullaO May be difficult with needle biopsiesO The cortex is recognized by a red “sunburst”

pattern corresponding to vascular tufts of glomeruli

O The medulla are seen as thin red streaks coursing through tan-white tissue

Kidney: Needle Biopsies

O From tips of the cortical end:O Freeze a 1mm section for immunofluorescenceO Submit an adjacent 1mm section in

glutaraldehyde for EMO If multiple cores are submitted, do the same

for each coreO If you cannot confidently identify an end with

cortex, do not guessO Submit 1mm sections from both ends of the

core

Kidney: Wedge Biopsies

O Freeze a full-thickness section of cortex for immunofluorescence

O Submit 1mm3 sections from the cortex in glutaraldehyde for EM

O Submit the rest for routine histology

Nephrectomies for Neoplastic Disease

O Weigh and measure the specimenO Orient the specimen

O The ureter is a useful landmark: the downward course of the ureter points to the inferior pole of the kidney

O Identify ureter, renal artery, and renal veinO Take shave margin from eachO Open with scissors to the point at which it

enters the kidneyO Look for presence of vascular invasion,

atherosclerosis, and thrombosis


O Inspect the mucosa and wall of the ureterO Is the ureter dilated or strictured?O Are any masses present?

O Ink soft tissue marginsO Bivalve the kidney to easily visualize

relationship of tumor to kidneyO Describe cortex, medulla and collecting

systemO Once tumor is exposed, may need fresh tissue

for special studiesO EM, immunofluorescence, cytogenetics


O Describe the shape, size, color, and consistency of the tumor

O Is the tumor in the cortex, medulla, or pelvis?

O Measure the distance of the tumor to nearest margin

O Note its relationship to the perinephric fat, renal pelvis, renal vein, ureter, and adrenal gland

O Take a photograph


O The outer surface of the fat represents Gerota’s fasciaO Ink the surface where it overlies the tumorO Submit perpendicular sections to show

relationship of tumor to soft tissue marginO Carefully peel back perinephric fat, examine

capsular surface, look for tumor extension through the capsule

O Note any bulges and document any disruption of the normal contour of the kidney surface


O Submit sections that include the tumor, adjacent non-neoplastic kidney, and overlying capsule

O Make additional sections through tumor and surrounding kidney

O Look for satellite tumorsO Submit at least four sections of tumor to demonstrate

relationship to parenchyma, renal pelvis, major vessels, renal capsule, and perinephric fat

O Section through the remainder of the kidneyO Submit one or two sections of non-neoplastic kidneyO Submit one or two sections of fat to assess infiltration

by tumor


O If adrenal gland is present:O Weigh itO Measure itO Submit a section

O Look for lymph nodes in kidney hilum

Partial NephrectomiesO Same approach as total

nephrectomyO Don’t forget to sample renal

parenchymal marginsO Ink and submit perpendicular sections

to demonstrate distance to tumorO Often you will not be able to assess

relationship of tumor to perinephric fat, renal vein, ureter, or other structures

Nephrectomies for Non-neoplastic Disease

O Essentially the same as nephrectomy for neoplastic disease

O Establish patient’s clinical historyO Determine if fresh tissue is needed for

immunofluorescence or EMO Evaluate kidney, hilum and

perinephric fat using the guidelines for neoplastic nephrectomies

O If calculi are identified, submit for chemical analysis

Cystic KidneysO Resected for congenital or acquired non-neoplastic

diseaseO Kidneys may be massively enlarged or distorted

O Follow same guidelines as previously notedO Probe ureters to check for patencyO Note the location of the cysts in terms of their

relationship to cortex and medullaO Document size and contents of cystsO Thoroughly section and submit the kidney

O Cystic kidneys can harbor unsuspected neoplasmsO Submit sections of solid foci, cysts with thickened

walls, and cysts with a papillary lining

CPT CodesO Kidney Biopsy – 88305O Complete/Partial Nephrectomy -

88307

Renal and Ureteric CalculiO Sent for gross examination only

O CPT code 88300

O Need to be sent for chemical analysis for identification purposes

O Indicate how many stones (or aggregate) and the shape, consistency and color

Pediatric Renal Neoplasms

O Often primarily resected and must be carefully processed to ensure accurate staging

O Photograph the intact specimenO Carefully examine the contour of the kidney

and tumorO Identify potential sites of capsular

penetrationsO Ink the surfaceO Submit shave sections of vascular and

ureteral margins


O Bivalve the specimenO Obtain fresh tissues needed for

special studiesO Photograph the bivalved specimenO Make cuts parallel to the initial

bivalving incision at 2-3cm intervalsO Obtain the remaining sections after

fixation


O Take sections from the periphery of the lesion showing the following:O Nature of the tumor-kidney junctionO Relationship of tumor to the renal capsuleO Relationship of tumor to the renal sinusO Areas of the tumor that appear different

O Necrosis, hemorrhageO Always indicate the exact site from which

each section is takenO Easily accomplished with photographs


O Carefully section and inspect the normal kidney, particularly adjacent to the tumorO May show nephrogenic rests, the

precursor lesion of nephroblastomasO Carefully dissect the hilar and

perinephric tissues for lymph nodes

Wilms TumorO Wilms tumor occurs in approximately

1 in every 10,000 children in the USO Most common primary renal tumor of

childhood O Fourth most common pediatric

malignancy in the USO Usually occurs between 2 and 5

years of age, 95% occur before the age of 10

Wilms TumorO Presents as large,

solitary, well-circumscribed mass

O Cut surface is soft, homogenous, and tan-gray with occasional foci of hemorrhage, cyst formation and necrosis

Staging of pediatric renal neoplasms (From National Wilms’ Tumor Study)

O Stage I: Tumor confined to kidney, completely excisedO Intact renal capsuleO Infiltrated but not penetrated renal

capsuleO Renal sinus vessels not infiltratedO Renal vein contains no tumor

(intrarenal vessels may be involved)O Lymph nodes contain no tumorO No distant metastases


O Stage II: Tumor extends out of the kidney but is completely excised, and there is no evidence of nodal or distant metastasesO Tumor penetrates renal capsule into perirenal

fatO Tumor capsule biopsied, without diffuse

peritoneal spillageO Tumor infiltrates renal sinus vesselsO Tumor in renal vein, removed without cutting

across tumorO Tumor infiltrates adjacent organs or vena cava,

but is completely resected


O Stage III: Tumor is incompletely excisedO Tumor is incompletely excisedO Surgical margins involved by tumorO Tumor in lymph nodesO Tumor thrombus transectedO Peritoneal implants presentO Tumor removed in more than one part

Learner Evaluation

Question 1:O This tumor presents as a large,

solitary, well circumscribed mass with a soft, homogenous, tan-gray surface and is the most common primary renal tumor of childhood.

A. Clear Cell CarcinomaB. Xp11 Translocation CarcinomaC. Wilms TumorD. Renal Papillary Adenoma

Answer 1:C. Wilms Tumor

Question 2:O What is the significance of relative

constrictions of the ureters?A. They are potential sites of

obstruction by ureteric stonesB. These areas are more common for

neoplasm to occurC. They aid in continenceD. They are areas where vessels come

in and out of the ureters

Answer 2:A. They are potential sites of

obstruction by ureteric stones

Question 3:O List the pertinent margins of a

nephrectomy.

Answer 3:O Ureter, renal artery, renal vein

Question 4:O Anatomically, the kidneys are the

only organ that are truly located in this region.

A. Peritoneal cavityB. AbdomenC. PeritoneumD. Retroperitoneum

Answer 4:D. Retroperitoneum

Question 5:O These neoplasms are typically bright

yellow-gray-white spherical masses and have areas of gray-white necrosis.

A. Papillary carcinomaB. Wilms tumorC. Clear cell carcinomaD. Chromophobe carcinoma

Answer 5:C. Clear cell carcinoma

Question 6:O In a pediatric nephrectomy, the

tumor extends out of the kidney but is completely excised and there is no evidence of nodal or distant metastases. What is the most likely stage of this tumor?

A. Stage IB. Stage IIC. Stage III

Answer 6:B. Stage II

Question 7:O The kidneys and perirenal fat are

encapsulated by a layer of connective tissue called _____________?

Answer 7:O Gerota’s fascia

Question 8:O In pediatric renal neoplasms, sections

from the periphery of the lesion should be taken to show the following:

A. Nature of the tumor-kidney junctionB. Relationship of tumor to renal capsuleC. Relationship of tumor to renal sinusD. Areas of the tumor that appear differentE. A, B, and C onlyF. All the above

Answer 8:F. All the above

Question 9:O What is the CPT code for renal and

ureteric calculi?A. 88300B. 88302C. 88305D. 88307

Answer 9:A. 88300

Question 10:O According to the CAP staging of kidney

tumors, which neoplasm would be of the highest stage?

A. Tumor grossly extends into the vena cava above the diaphragm

B. Tumor invades beyond Gerota’s fasciaC. Tumor is more than 10cm, limited to the

kidneyD. Tumor grossly extends into the renal

vein

Answer 10:B. Tumor invades beyond Gerota’s

fascia

ReferencesMoore, K. L., Dalley, A. F., & Agur, A. M. (2014). Clinically Oriented Anatomy (7th ed.). Baltimore, MD: Lippincott Williams & Wilkins.

Kumar, V., Abbas, A., & Aster, J. (2015). Robbins and Cotran Pathologic Basis of Disease (9th ed.). Philadelphia, ME: Elsevier.

Srigley, J. R., Amin, M. B., Campbell, S. C., Chang, A., Delahunt, B., Grignon, D. J., & Humphrey, P. A. (2013). Protocol for the Examination of Specimens From Patients With Invasive Carcinoma of Renal Tubular Origin. In AJCC/UICC, TNM(7th ed.). N.p.: College of American Pathologists.

Westra, W. H., Hruban, R. H., Phelps, T. H., & Isacson, C. (2003). Surgical Pathology Dissection (2nd ed.). New York, NY: Springer.

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