Genitourinary Specimens

Relevant clinical history

Relevant clinical history, in addition to gender and age, is often necessary or helpful to interpret specimens from the kidney ( Table 17.1 ).

Processing the specimen

• 1.

  A medical kidney biopsy is usually performed by a nephrologist in conjunction with a radiologist, under ultrasound guidance. Occasionally, the radiologist may perform a percutaneous biopsy under CT guidance, or a transjugular biopsy in the angiography suite. After each pass, the core needle biopsy (ideally 15-gauge) is examined unfixed under stereomicroscopy by the renal pathologist to assess the adequacy of the specimen and to determine the need for additional biopsies ( Fig. 17.1 ). The consensus classification for adequacy of a transplant biopsy recommends there must be 10 or more glomeruli and two arteries.

  

  Biopsies are examined and divided for light microscopy, immunofluorescence (IM), and electron microscopy (EM), which are performed routinely on every medical renal biopsy. The amount of needed tissue and type (cortex or medulla) will differ for each situation and depends on the clinical differential diagnosis, the focality of the expected disease process, pathologist’s experience, patient tolerance of the procedure, and any complications (e.g., bleeding).

• 2.

  Clean forceps must be used when allocating tissue for light microscopy, IF, and EM! Minute amounts of formalin or glutaraldehyde can destroy the antigenicity of the tissue allocated for IF and glutaraldehyde can create problems in interpreting tissue for light microscopy.

  Representative cortex and, if available, medulla (for evaluation of casts), are allocated for IF by placement in Zeus transport solution (Michel’s solution).

  A few viable glomeruli are usually sufficient for placement in Karnovsky’s glutaraldehyde/paraformaldehyde fixative for EM.

• 3.

  The remaining tissue is fixed in formalin. Each core is placed separately in a nylon biopsy tissue bag. Institutions will have protocols for routine studies.

Processing the specimen

• 1.

  Weigh the kidney (normal is 125–170 g for males and 115–155 g for females) and record the measurements. Record the length and diameter of the hilar vessels and ureter. Look for patency or obstruction of vessels (thrombosis, intimal proliferation, atherosclerotic plaques).

• 2.

  Describe the renal parenchyma including color (tan/red, gray/green), thickness of cortex, shape of calyces and papillae (normal or blunted), state of pelvis and ureter, vessels, infarcts (size and location), hemorrhage, and necrosis.

• 3.

  Submit four cassettes including cortex and medulla, hilar vessels, and any lesions. Allocate tissue for EM and IF microscopy.

Processing the specimen

• 1.

  Weigh the kidney (normal is 125–170 g for males and 115–155 g for females) and record the measurements. Record the length and diameter of the hilar vessels and ureter. Look for patency or obstruction of vessels (thrombosis, intimal proliferation, atherosclerotic plaques).

• 2.

  Describe the renal parenchyma including color (tan/red, gray/green), thickness of cortex, shape of calyces and papillae (normal or blunted), state of pelvis and ureter, vessels, infarcts (size and location), hemorrhage, and necrosis. The number and size of cysts are recorded.

  The entire kidney is thinly sectioned and carefully examined. The lining of cysts is examined for any areas of thickening or irregularities as these may be neoplastic. Solid lesions are also suspicious for neoplasia. Allocate tissue for EM and IF microscopy.

• 3.

  Submit four cassettes including cortex and medulla and hilar vessels.

  Additional cassettes are submitted to evaluate any solid or cystic areas suspicious for carcinoma (1 tissue section per 1 cm of suspected tumor).

Routine PAS, Jones’ methenamine silver, and trichrome stains on the normal renal cortex may be ordered.

Processing the specimen

• 1.

  Weigh the entire specimen and record its dimensions. Examine the hilum carefully and identify the ureter, renal vein, and renal artery. The vessels and ureter will usually be tied off with sutures or stapled.

  It is useful to determine if renal vein invasion was seen on preoperative radiologic studies prior to gross evaluation to aid in specifically documenting this finding. Involvement of the renal vein and segmental branches changes the T classification to pT3a and is important for staging and prognosis.

  Tumor involvement of the renal vein may be obvious grossly and has the appearance of a smoothly surfaced projection of tumor extending out from the hilum. The vessel wall often retracts around a tumor thrombus that is not attached to the wall, resulting in the intravascular tumor being present at the “margin.” However, the vein margin is only considered positive when the tumor is adherent to the vessel wall at the margin. This finding must be carefully evaluated and documented.

  Take en face cross sections of the margins (vein, artery, and ureter) and place in a labeled cassette.

• 2.

  Inspect the outer portion of the specimen. The kidney is surrounded by perirenal fat. Surrounding this fat, the kidney, and the adrenal gland is within a renal fascia (“Gerota’s fascia”).

  Ink the outer surface of the specimen including perirenal fat and areas of exposed kidney.

  A probe placed in the ureter and renal vessel (vein if unobstructed by tumor; artery if minimally atherosclerotic) assists in making a cut through the center of the kidney. Cut along the probes to bisect the ureter and vein and extend the cut to divide the kidney. This method facilitates the complete evaluation of the urothelium in cases of UCC. The kidney is bivalved with a single longitudinal cut. Cut the kidney completely through into two separate halves. If the mass is not well visualized with the central slide, cut additional slices parallel to the first. Photograph one half of the kidney with the mass. The color of the tumor and gross appearance can help with subtyping and staging, respectively.

  Describe all lesions including size, number (both RCC and UCC may be multifocal), appearance, necrosis, location (with respect to the upper and lower pole, cortex, medulla, pelvis), distance from margins (Gerota’s fascia, vascular, ureteral), involvement of calyceal or pelvic mucosa (open completely with scissors), gross invasion of capsule or into perirenal soft tissue, gross involvement of the sinus, and involvement of adjacent structures (renal vein, adrenal). It is important to note if the tumor demonstrates direct extension into the adrenal gland (pT4) or is present as a separate mass in the adrenal gland (M1). Make additional cuts (horizontal or perpendicular to the original cut) as necessary to assess the entire parenchyma.

  Renal sinus adipose tissue is located between the pelvicalyceal system and the renal parenchyma. The main lymphovascular supply of the kidney is located here and invasion into this tissue is important to document. Invasion of hilar adipose tissue also upstages the tumor to pT3. Multiple blocks of tissue may be submitted if the tumor is close to this area but tumor invasion into fat is uncertain.

  Describe the uninvolved renal parenchyma including color, thickness of the cortex, corticomedullary junction (well defined, effaced), shape of the papillae (blunted, necrotic), calyces, renal pelvis (dilation, petechiae, mucosa), presence of calculi, and types of cysts (simple are usually benign; complex cysts may be neoplastic). Note any tan/yellow or white nodules in the cortex that might be a cortical “adenoma” or additional foci of tumor.

  Palpate the hilar region for any lymph nodes and save in a labeled cassette. Typically, hilar lymph nodes are only found in about 22% of patients.

  A section of normal cortical and medullary tissue located away from the tumor and scarring is taken for light microscopy and possible IF and the cortex is sampled for possible EM (see above). Routine PAS, Jones and silver stains on the non-neoplastic tissue block may be ordered. Examination of the non-neoplastic kidney reveals significant disease in over half of patients. This information is important to identify the patients most likely to develop chronic renal disease in order to implement early preventative therapy and treatment.

• 3.

  Fix the entire specimen in formalin overnight. Large tumors should be bivalved with additional parallel slices as needed. Formalin-soaked gauze is placed between the slices to wick formalin around the sections.

• 4.

  The following day sections of the tumor (at least 1 per cm), margins, and kidney are taken. Grossly different areas should be sampled, including an interface between any areas that are grossly different in appearance (i.e., yellow vs. brown vs. fleshy/tan). Pay special attention to white fleshy areas as these may represent areas of sarcomatoid transformation; document in the gross description the approximate amount (in percent) of white/fleshy tumor.

  The adrenal gland may be present at the upper pole. Free the gland from the surrounding fat and describe including color, size, nodularity (see Chapter 8 ). Section the gland carefully looking for evidence of tumor metastasis (nodules). If abnormal, weigh the gland and/or focal lesions.

• 5.

  Carefully section through the remainder of the fat looking for lymph nodes. Any nodes present are usually near the renal hilum.

• 6.

  Sample the tumor showing the closest approach to the renal capsule.

• 7.

  Sample perirenal and hilar adipose tissue, including tumor if it is close to this tissue.

• 8.

  Rarely, a portion of rib may be submitted with the nephrectomy specimen. See Chapter 11 for instructions on processing.

• 9.

  One full-thickness section including both cortex and medulla, located away from the tumor, is taken. Routine PAS, Jones’ methenamine silver, and trichrome stains may be ordered on this section for evaluation of renal disease.

Gross differential diagnosis

Renal tumors often have distinctive appearances and can be distinguished grossly ( Fig. 17.2 ).

• Renal cell carcinoma: The most common type is clear cell (conventional) carcinoma (75% of cases), followed by papillary carcinoma (10%), chromophobe carcinoma (5%), and other rare types. Some RCC’s arising in kidneys with ACD may be quite subtle and can have the appearance of an irregular area of papillary projection within a cyst (ACD-associated RCC).

• Clear cell (conventional) RCC is the most common type of renal carcinoma. This carcinoma is usually golden yellow to red, spongy to firm, and occurs in discrete nodules with pushing borders. An older term for this cancer, hypernephroma, refers to the gross resemblance of the color of this tumor (“canary yellow”) to the adrenal gland cortex, as both are composed of cells with abundant cytoplasmic lipid. The tumor may appear brown if the cytoplasm is granular. Prominent thin-walled blood vessels and blood lakes are typical. Necrosis may be present. Cysts may be absent or quite prominent. The tumor may bulge out beyond the contour of the renal capsule and sometimes will invade through the capsule into adipose tissue. Invasion may occur into the renal sinus adipose tissue where there is no capsule.

• Papillary RCC is a well-circumscribed tumor with a fibrous pseudocapsule (papillary adenomas lack a fibrous capsule). The tumors are soft and friable because of the papillary architecture. The color ranges from brown (due to hemosiderin) to tan/yellow (due to abundant foamy macrophages). Some appear to be necrotic due to the soft texture and some are actually necrotic. Hemorrhage and cystic areas are common. Some are multifocal, although small tumors (up to 1.5 cm) may be classified as papillary adenomas.

• Chromophobe RCC is usually a small to large well-circumscribed solitary tumor without a surrounding capsule. A central scar is present in about 15%. The color is pale tan to dark brown associated with cytoplasmic iron. Necrosis or hemorrhage is seen in about a third of cases. Cystic change is uncommon.

• Collecting duct carcinomas occur in the renal medulla and have a hard gray/white appearance. The borders are typically irregular and tumor typically infiltrates between glomeruli and tubules. The majority invade into the renal sinus and perinephric adipose tissue. Necrosis, hemorrhage, and cystic change are frequent.

• ACD-associated carcinomas occur in the setting of cystic disease associated with renal failure and long-term hemodialysis. The tumor grows in a cystic space in a background of other cysts. The cancers are well circumscribed and can be multifocal and bilateral. They are tan to yellow brown and can have areas of necrosis and hemorrhage. Long-term hemodialysis (>10 years) is a risk factor for developing an ACD-associated RCC.

• Clear cell tubulopapillary renal cell carcinoma occurs in patients with and without end-stage renal disease. The cancers are usually small and well circumscribed with a tumor capsule and may be cystic. No hemorrhage or necrosis is seen.

• Sarcomatoid differentiation has the appearance of gray/white firm to fleshy areas detected in cancers of other histologic types. Any area of this appearance should be documented (give overall percent of tumor) and sampled. Hemorrhage and necrosis are common.

• Urothelial cell carcinoma is usually a tan/pink friable mass with a minute villous architecture. There may be a rather small base, compared to the size of the tumor, attached to the renal pelvic urothelium. However, some tumors have a broad base and involve the majority of the urothelium of the renal pelvis. The tumor can have retrograde growth up collecting tubules or directly invade the renal parenchyma. The ureter may also be involved.

• Renal cortical adenomas are usually well circumscribed, unencapsulated gray or yellow benign tumors present below the renal capsule. They are typically an incidental finding and are less than 1.5 cm in size. They are sometimes associated with long-term hemodialysis or chronic pyelonephritis and are most frequently papillary in architecture.

• Metanephric adenomas are well-circumscribed benign tumors but can range in size from 1 to 15 cm. The color is fleshy tan/yellow and hemorrhage or necrosis should not be present.

• Oncocytomas are usually deep red/brown, soft, and well-circumscribed benign tumors, without areas of necrosis, located in the cortex. Central “scarring” is present in about half of cases, especially in larger tumors.

• Other types of neoplasia: Rare renal tumors include fumarate hydratase-deficient RCC, succinate dehydrogenase-deficient RCC, translocation (Xp11.2) RCC, mucinous tubular and spindle cell carcinoma, tubulocystic carcinoma, malignant perivascular epithelioid neoplasm (PEComa), mixed epithelial and stromal cell tumor, primary sarcoma, and others.

• Pediatric tumors: The types of renal tumors occurring in children are quite different than those seen in adults and include nephroblastoma (Wilms tumor), clear cell sarcoma, rhabdoid tumor, mesoblastic nephroma, lymphoma, and neural tumors, as well as RCC, and angiomyolipoma. The College of American Pathologists (CAP) “Protocol for the Examination of Resection Specimens from Patients with Wilms and Other Pediatric Renal Tumors” has additional information on the sampling and reporting of these tumors (available at https://www.cap.org ). The Childrens Oncology Group Staging System can be used for Wilms tumors ( Table 17.5 ). There is not an AJCC staging system for Wilms tumors.

Nephrectomy weight in pediatric kidney tumors is used as an eligibility factor for some clinical trials and is important to document. The specimens may be processed as above but additional sections should be taken to document the relationship of the tumor to the normal kidney (to identify the invasive pattern of the tumor), the relationship of the tumor to the renal sinus and sinus vessels (important to define stage 2 disease), and to evaluate the relationship of the tumor to the capsule. Normal appearing cortex should also be sampled. Because these tumors tend to be more heterogeneous in appearance, at least 1 section per cm of greatest tumor dimension should be taken including all areas of differing appearance. If there is more than one tumor nodule, each nodule should be sampled. It is important to document the location of each section taken on a diagram or photograph to appropriately classify these tumors. Some treatment protocols require that the patient have negative lymph nodes. Therefore, all hilar tissue should be examined microscopically.

Tissue should also be taken for special studies:

• Snap-frozen: The National Wilms Tumor Study Protocols (see www.nwstg.org ) require snap-frozen tissue (in liquid nitrogen or cold isopentane) from all pediatric renal tumors and adjacent normal tissue (preferably 1 g or a minimum of 100 mg in two or more vials along with a separate portion of normal kidney in at least one vial). Nephrogenic rests may also be frozen. Adjacent tissue should be sampled for formalin fixation for histologic correlation.

• EM: EM may occasionally be of use.

• Touch preparations : Fixed in 95% alcohol. Can be used for some studies (such as in situ hybridization) if other tissue is not available for these studies.

• Flow cytometry: In some cases flow cytometric analysis of ploidy, S-phase fraction, or surface markers (i.e., for lymphomas) may be requested.

• Genetics: Genetic studies may be useful for classification and prognosis as some tumors have specific genetic alterations:

• Cellular mesoblastic nephromat(12;15)

• Malignant rhabdoid tumor22q11.2 deletion

• Wilms tumordel 11p13

• Nephroblastoma (Wilms tumor): This is the most common type of pediatric renal tumor (80% of total) and occurs in children from 1 to 6 years of age. Most are well-circumscribed lobulated masses with a variegated appearance from gray to pink. Extensive necrosis and hemorrhage are common. If there are multiple nodules, each should be sampled. Cysts may be present. The tumor may invade into the renal vein, ureter, or adipose tissue.

• The weight of the kidney may be used as an eligibility factor for clinical protocols and must be determined accurately.

• At least 1 section per cm of tumor should be taken, as tumors can be quite heterogeneous. Most sections should be taken from the periphery to evaluate the relationship to the capsule, the renal sinus, the normal kidney, and possible vascular involvement.

• The renal sinus (the hilum of the kidney occupied by the renal pelvis, hilar vessels, and fat) should be well sampled as tumors often involve vessels at this point. The renal cortex lacks a capsule at this point. The tumor often involves the renal vein as a tumor thrombus. The vein may retract around a tumor thrombus. This should not be interpreted as a positive margin if the thrombus is not transected.

• If the patient has been treated, the response to treatment is classified according to the percent of residual viable tumor. It is important to document the location of sections and to sample the entire tumor bed in order to make this determination.

• Nephrogenic rests: These are areas of persistent embryonal tissue and are found in more than one third of cases of Wilms tumor. They are found in <5% of pediatric kidneys removed for other reasons. The rests appear as grossly pale areas and are often subcapsular. Nephroblastomatosis is defined as multiple or diffusely distributed rests. The presence of nephrogenic rests and the type of rests (perilobar or intralobar) are associated with the probability of a syndrome and involvement of the contralateral kidney ( Table 17.2 ). Renal lobes are more easily seen in the kidneys of infants and children. Clear cell sarcoma: These make up 4% of renal tumors in children and occur between the ages of 1 and 3. Thirty percent present with metastases to lymph nodes. The tumor is usually a large well-circumscribed gray/white mass with pushing borders into the adjacent renal parenchyma. Focal necrosis and hemorrhage may be present.

  TABLE 17.2

  TYPES OF NEPHROGENIC RESTS *

  FEATURE	PERILOBAR REST	INTRALOBAR REST
  Site in renal lobe	Periphery (including subcortical)	Random; cortex, medulla, sinus
  Margins	Clearly demarcated	Poorly demarcated
  Relation to nephrons	No nephrons within rest	Dispersed between nephrons
  Composition	Blastemal or tubular; stroma scanty or sclerotic	Tubules, blastema, cysts; stroma usually predominates
  Number	Usually numerous	Often single
  Wilms tumor associations	Blastemal or epithelial predominant	Early-onset, stromal predominant or tumors showing divergent (teratomatous) differentiation
  Syndrome associations	Beckwith–Wiedemann syndrome, Perlman syndrome, and hemihypertrophy	WAGR syndrome and Denys–Drash syndrome

  * Modified from Sternberg’s Diagnostic Surgical Pathology, 2004.

• Rhabdoid tumor: Most are well defined and fleshy in appearance with frequent necrosis and hemorrhage. The renal pelvis is usually involved. These tumors are most common in infants below the age of 1 and rare in children older than 5.

• Congenital mesoblastic nephroma (CMN): These are rare tumors (2% of pediatric renal tumors) that occur in children from birth to 2 (most are less than 3 months old). The tumor is an irregular gray/white to tan mass often of large size. Cysts, necrosis, or hemorrhage are unusual. These tumors can involve the renal vein and the vessels at the hilum and this is an important prognostic factor. This area should be thoroughly sampled.

There are three types:

• Classic CMN (24% of cases) corresponds to infantile fibromatosis.

• Cellular CMN (66% of cases) corresponds to infantile fibrosarcoma and often have a t(12;15) or other variant translocation resulting in a fusion product. All relapses are of this type or mixed.

• Mixed CMN (10%) has features of both histologic types. Some of these tumors have EFGR activating mutations.

• Lymphoma: A well-defined homogenous gray to white mass involving the cortex or medulla.

• Cystic kidney disease: Genetic (presenting at birth or as an adult), sporadic, and acquired (due to long-term hemodialysis) forms of cystic kidney disease occur. The location and size of the cysts vary among the different types of cystic renal disease ( Table 17.3 ). Because of the increased risk of RCC in ACD, all cysts must be carefully examined for mural nodules or papillary projections. Xanthogranulomatous pyelonephritis: Appears as single or multiple golden yellow nodules in and around the pelvis and calyces. The nodules may rarely be found in the renal capsule or in adjacent fat. The gross appearance can mimic a RCC.

  TABLE 17.3

  TYPES OF CYSTIC KIDNEY DISEASE

  CYSTIC KIDNEY DISEASE
  DISEASE	KIDNEY SIZE	LOCATION OF CYSTS	SIZE OF CYSTS	CLINICAL CORRELATIONS
  Infantile polycystic kidney disease	Massively enlarged	Cortex and medulla, radially arranged and oriented perpendicular to renal capsule	Small	Autosomal recessive Can also affect liver (congenital hepatic fibrosis—Caroli disease) Usually fatal at birth
  Medullary sponge kidney	Normal	Arise in collecting ducts and found in medullary pyramids and renal papillae	Small <0.5 cm	Most sporadic—rarely hereditary Rarely progress to renal failure, associated with urolithiasis
  Medullary cystic kidney disease	Small, contracted, granular surface	Corticomedullary junction	Small <2 cm	Autosomal dominant Two types—gout often develops in type 2 Renal failure develops from 30 to 70 years
  Nephronophthisis/medullary cystic kidney disease	Small, contracted, granular surface	Corticomedullary junction	Small <2 cm	Autosomal recessive Four types—renal failure develops from 1 to 19 years 15% develop retinal disease
  Adult polycystic kidney disease	Normal to marked increase	Cortex and medulla	Small to very large (several centimeters)	Autosomal dominant Liver cysts may be present About half progress to renal failure in adulthood
  Acquired cystic disease	Small	Cortex	Variable—small to very large	Occurs after long-term hemodialysis. There is an increased risk of RCC

• Angiomyolipoma : These tumors consist of dystrophic vessels, smooth muscle (gray/white), and adipose tissue (yellow) in varying proportions. The tumor is usually circumscribed with a variable appearance depending on the components of the tumor. Smooth muscle predominant tumors resemble leiomyomas and adipose predominant tumors resemble lipomas. The radiologic appearance is often diagnostic due to the presence of adipose tissue and vessels within the tumor. The vascular component is often associated with hemorrhage. The tumor may be confined to the kidney or extend through the capsule. Rare cases may involve the renal vein or regional lymph nodes. The gross appearance can closely mimic a RCC and some tumors are associated with RCC. This is a very common tumor in patients with tuberous sclerosis (in this setting they can be multifocal and bilateral), but the majority of tumors occur in patients without this disease.

Microscopic sections

Sample dictation

• Part A, received fresh and labeled with the patient’s name, medical record number, and “right kidney” consists of a radical nephrectomy specimen (296 g, 12.3 × 11.9 × 3.2 cm) including ureter (12.3 cm long, 0.3 cm in diameter), renal vein (2.1 cm long, 2.0 cm in diameter), renal artery (0.9 cm long, 0.3 cm in diameter), kidney proper (15.6 × 8.2 × 4.1 cm), and perirenal adipose tissue (up to 3.1 cm thick). Adrenal is not identified. The outer surface is inked blue.

  There is a well-demarcated, variegated yellow–red to brown, solid hemorrhagic mass (4.1 × 3.5 × 2.7 cm) in the mid–upper pole involving approximately 20% of the kidney. The mass is 3.1 cm to the renal vein margin, 2.5 cm to the renal artery margin, 13.6 cm to the ureter margin, and 3.0 cm to the inked outer surface. The mass does not involve the renal vein, distorts but does not grossly invade the renal sinus, and is confined to the kidney without involvement of the perirenal adipose tissue. The remainder of the kidney contains a well-defined corticomedullary junction and a unilocular cortical cyst (0.6 cm in greatest dimension) filled with clear serous fluid in the lower pole.

  Gross photographs are taken. Representative mass and normal is submitted for tissue bank and research. Representative normal kidney cortex is allocated for EM/IF on hold. Representative sections are submitted for microscopic evaluation.

  Micro A1: Ureter, artery, and vein margins en face, three fragments.

• Micro A2–A3: Mass to sinus, two fragments.

• Micro A4–A5: Mass to inked radial margin, two fragments.

• Micro A6: Mass with normal kidney and pelvis, one fragment.

• Micro A7: Parenchyma and cortical cyst, two fragments.

• Micro A8: Uninvolved parenchyma, one fragment.

Processing the specimen

• 1.

  The entire specimen is weighed.

• 2.

  The fragments are separated into groups based on the gross appearance:

  Suspicious for tumor or cyst wall

  Suspicious for hilar structures—vessels or ureter

  Normal appearing renal parenchyma

• 3.

  The probability of sampling a tumor in a given number of cassettes is related to the size of the tumor and the size of the kidney. The tumor-to-kidney volume ratio is defined as the volume of the tumor divided by the volume of the kidney. ¹⁷

  The volume of the tumor is calculated using the radius (half the largest dimension by imaging) and assuming the tumor is a solid sphere. Thus, the volume of a 3 cm tumor (i.e., the radius is 1.5 cm) is:

  4/3 × 3.14 (Pi) × 1.5 ³ = 14.13 cm ³ .

  The volume of the kidney is approximated by the weight.

  Thus, if the kidney weighs 200 g, the tumor-to-kidney volume ratio is 14.13/200 = 0.071.

  The probability of sampling this 3 cm tumor is 75% if 10 blocks are submitted, 90% if 16 blocks are submitted, and 99.99% if 32 blocks are submitted. ¹⁷

  However, in one study of morcellated kidneys, the fragments containing cancer could be grossly identified in all cases.

• 4.

  If a tumor was suspected by imaging, and the initial samples do not show tumor, additional tissue should be evaluated.

Pathologic prognostic/diagnostic features sign-out checklist for renal tumors

This checklist incorporates information from the CAP Cancer Committee protocols for reporting on cancer specimens (see www.cap.org/ ) as well as other resources. The specific details of reporting the elements may vary among institutions.

There is a separate CAP Cancer Protocol for the reporting of pediatric Wilms tumor (see “Cancer Protocols and Checklists” at www.cap.org ).

Relevant clinical history

In addition to age and gender, relevant clinical history is often necessary or helpful for the interpretation of specimens ( Table 17.7 ).

The bladder muscularis mucosae (small bundles of smooth muscle) are poorly defined (not unlike the gallbladder!) and incomplete. Therefore, the term lamina propria is used and “submucosa” is not used. Invasion is reported as being into the lamina propria or deeper into the muscularis propria (large, thick bundles of smooth muscle)