Handling of kidney

specimens

DONE BY : DR RAMI AMAWI

Gross Anatomy of The Kidney

kidney specimens (types)

1) Needle or Wedge Biopsies

2)Nephrectomy

Needle or Wedge Biopsies

♦ “Medical” renal biopsies are typically performed for evaluation of renal function or urinary abnormalities and are assessed in the context of the clinical presentation of the patient, with particular attention to the results of serological tests and the urinalysis

♦ Resectable kidney masses are rarely biopsied because of the virtually diagnostic appearance of tumors on CT scan and the need for resection for treatment.

♦ Unresectable tumors are usually diagnosed by FNA.

♦ Occasionally, biopsies will be performed on kidneys with tumors that will be treated with cryotherapy, or before a kidney is used for transplantation.

Needle or Wedge Biopsies

• The 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.

Processing of Needle or

Wedge Biopsies ♦ Biopsy is examined unfixed under stereo-

microscopy by the renal pathologist to assess the adequacy of the specimen and to determine the need for additional biopsies.

♦ The consensus classification for adequacy of a transplant biopsy recommends that there must be 10 or more glomeruli, and two arteries.

Cont .. Processing of Needle or Wedge Biopsies

♦ 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.

♦ The remaining tissue is fixed in formalin. Tissue sections are cut at 3 to 4 microns. Special stains are evaluated on all renal biopsies (H&E, PAS, Jones’ silver methenamine, and AFOG trichrome

Nephrectomy specimen

• Nephrectomies are performed for :

1) tumors (usually renal cell carcinoma, rarely urothelial (transitional) cell carcinoma of the renal pelvis)

2) remove nonfunctioning grafts. ((Transplant Nephrectomy))

3) Native nonfunctioning kidneys . ((Native Kidney Nephrectomy))

4) Partial nephrectomies are becoming more common to resect tumors if the other kidney is absent or nonfunctioning or if the primary tumor is small (e.g., a tumor found incidentally on CT

scan or ultrasound).

Transplant Nephrectomy

Native Kidney Nephrectomy

♦Transplant kidney may be removed due preexisting disease in the allograft, vascular insufficiency (e.g., thrombosis or plaque), rejection, or recurrence of the patient’s original renal disease.

♦ Nonfunctioning kidneys may be removed due to hypertension refractive to medical therapy, persistent pyelonephritis, severe renal protein loss, polycystic kidneys, or in patients with bilateral renal tumors. A native kidney may also be removed to provide a native ureter for the allograft.

Processing the transplanted nephrectomy & Native Kidney

Nephrectomy specimens♦ PROCESSING THE SPECIMEN

1. Weigh (normal is 125 to 170 gm for males and 115 to 155 gm for females) and record the measurements of the kidney. Record the length and diameter of any vessels at the hilum. Look for patency of vessels .

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

Cont.. Processing the transplanted nephrectomy & Native Kidney Nephrectomy

specimens3. Submit four cassettes including cortex and

medulla, hilar and request one vessels, and focal lesions

** H&E, PAS stain, Jones’ silver methenamine, and trichrome (AFOG) on one block containing kidney cortex .

** If the transplant has failed six months or more after transplantation, or if there is significant proteinuria, and recurrence of the patient’s original disease is suspected, always save cortex for EM and immunofluorescence

Partial Nephrectomy

♦ A partial nephrectomy is performed for a radiologically indeterminate mass, tumor in a solitary kidney (the contralateral nephrectomy may have been performed for prior tumor), or underlying disease expected to affect renal function (e.g. diabetes).

♦ PROCESSING THE SPECIMEN ((As previous specimens & ))

1. Examine the cut surface of the kidney for areas suspicious for tumor. Ink this margin. Often, the surgeon will indicate the resection margin using a surgical suture. Because orientation and evaluation of this margin is very important, contact the surgeon for orientation if necessary. Serially section through the specimen. Describe the distance of the tumor from the cut renal resection margin.

Cont.. Processing the Partial Nephrectomy

specimen

2. No major vessels or the ureter will be present.

3. Take multiple sections demonstrating the relationship of the tumor to the renal resection margin as well as to the deep (perirenal fat) margin.

Laparoscopic Nephrectomy with Morcellation

♦ Laparoscopic surgery offers numerous advantages for patients. However, in order to remove tissues and organs through a small skin incision, they must be morcellated (i.e., reduced to small fragments)

♦ This procedure introduces new challenges to pathologists. It may not be possible to determine the size, status of margins, and renal vein involvement for such specimens.

♦ However, this information can also be determined from imaging studies and the decreased morbidity to the patient may outweigh the loss of specific pathologic confirmation.

♦ Cytology washings from the retrieval bag can also provide a diagnosis in the majority of patients.

Radical Nephrectomy

Radical nephrectomies : consist of the kidney, most of the

ureter, renal vein and artery, perinephric fat, and surrounding

Gerota’s fascia. An adrenal gland may or may not be present.

♦ PROCESSING THE SPECIMEN1. * Weigh the entire specimen and record its

dimensions. Examine the hilum carefully and identify the ureter, renal vein, and renal artery. The vessels will usually be tied off with

* Take cross-sections of the margins (vein, artery,

and ureter) and place in a labeled cassette. * Palpate the hilar region for any lymph nodes and

save in a labeled cassette. Typically lymph nodes are not found.

Cont … Processing of the radical nephrectomy

specimen2. * Inspect the outer portion of the specimen. The kidney is

surrounded by perirenal fat which surronded by (“Gerota’s fascia”). If there are areas suspicious for tumor at the margin ink these areas selectively.

* The kidney is then bivalved with a single longitudinal cut. If the section starts at the hilum, place a probe into the ureter. Cut along the probe to bisect the ureter and extend the cut to divide the kidney. This method facilitates the complete evaluation of the urothelium in cases of urothelial (transitional) cell carcinoma.

* Alternatively, start at the side of the kidney opposite the hilum and bivalve the kidney, but do not cut completely through the hilum

Cont … Processing of the radical nephrectomy

specimen• Describe all lesions including size, number (both RCC and TCC may

be multifocal), location (with respect to the upper and lower pole, cortex, pelvis), distance from margins (Gerota’s fascia, vascular, ureteral), involvement of calyceal or pelvic mucosa (open completely with scissors), gross invasion of capsule, perirenal soft tissue,or hilar soft tissue, involvement of adjacent structures (renal vein, adrenal).

• Make additional cuts as necessary to assess the parenchyma. 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 represent tumor). Note any tan/yellow or white nodules in the cortex that might representa cortical “adenoma” or additional foci of tumor.

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

Cont … Processing of the radical nephrectomy

specimen► MICROSCOPIC SECTIONS :

• Tumor: Three to four cassettes including portions of tumor with varying appearance, relationship to adjacent uninvolved tissue, invasion of adjacent structures .

• Margins: Radial margin in perirenal fat, vascular margins & ureteral margin (these latter three sections can be submitted in the same cassette).

• Other lesions: Cysts, infarcts, adenomas, etc. One section of each.

Cont … Processing of the radical nephrectomy

specimen• Normal kidney: At least one cassette of

uninvolved kidney. If an underlying disease is suspected that could affect the other kidney, tissue for EM or immunofluorescence and special stains may be indicated.

• Adrenal: At least one cassette demonstrating normal adrenal. Additional cassettes to demonstrate lesions.

• Lymph nodes: Submit all lymph nodes found.

GROSS DIFFERENTIAL DIAGNOSIS

• Inflammatory/Necrotic Renal Lesions

• Renal Cystic Diseases• Benign Epithelial Tumors• Renal Cell Carcinomas• Childhood Tumors• Mesenchymal and Other Tumors• Truma

Inflammatory/Necrotic Renal Lesions

• Xanthogranulomatous Pyelonephritis

• Renal Cortical Necrosis • Renal papillary Necrosis

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 renal cell carcinoma

Renal Cortical Necrosis

Early phase shows yellow discoloration of cortex (hemorrhagic if blood supply is reestablished) and subcapsular and juxtamedullary congestion. Late phase shows cortical fibrosis with thinning and calcifications.

Renal papillary Necrosis

necrosis of renal papillae/medullary portion

Renal Cystic Diseases• Adult Polycystic Kidney

Disease• Autosomal Recessive

Polycystic Kidney Disease• Medullary Cystic Disease • Acquired Cystic Disease• Medullary Spong kidney• Simple Cortical Cyst

Benign Epithelial Tumors

• Papillary Adenoma • Renal Oncocytoma • Metanephric Adenoma

Papillary Adenoma

Well-circumscribed, unencapsulated pale tumor in subcapsular kidney

Usually 0.5 cm or smaller

Oncocytomas

Usually deep red/brown, soft, and well circumscribed

Without areas of necrosis . Located in the cortex. Central

“scarring” is present in about half of cases

Metanephric Adenomas

Well circumscribed but can range in size from 1 to 15 cm.

The bcolor is fleshy tan/yellow, Hemorrhage or necrosis may

be present.

Renal Cell Carcinomas• Clear cell carcinomas• Papillary carcinoma• Chromophobe carcinoma• Collecting duct carcinoma• Renal Medullary Carcinoma• Acquired Cystic Kidney

Disease Associated Renal Cell Carcinoma

• Renal cell carcinoma with Sarcomatoid differentiation

Clear cell carcinomas

Are usually golden yellow to red Spongy to firm Occur in discrete nodules with pushing borders. Blood lakes are typical. Necrosis may be present. The tumor may bulge out beyond the contour of the renal capsule, but rarely invades into adipose tissue.

Papillary carcinoma

Are brown (due to hemosiderin)

Very soft and friable May appear to be

necrotic (although they usually are not).

Chromophobe carcinoma

Are usually well circumscribed Tan/brown in color Possible focal necrosis or hemorrhage

Collecting duct carcinoma

Occur in the renal medulla and have a hard gray/white appearance. The borders are typically irregular. Necrosis is frequent. Gray/white firm to fleshy m

Renal Medullary Carcinoma Centered in medullary region of the kidney with white or gray cut surfaces and central necrosis is common .

Acquired Cystic Kidney Disease Associated Renal Cell

Carcinoma May be quite subtle and have

the appearance of an irregular area or papillary projection within a cyst.

Renal cell carcinoma with Sarcomatoid differentiation Gray/white firm to fleshy masses. Hemorrhage and necrosis are common.

Urothelial (Transitional) Cell Carcinoma

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.

Pediatric Tumors

• Nephroblastoma (Wilms tumor)

• Clear cell sarcoma• Rhabdoid tumor• Congenital mesoblastic nephroma

Nephroblastoma (Wilms tumor)

Most are well circumscribed lobulated masses with a variegated appearance from gray to pink.

Extensive necrosis and hemorrhage are common.

Cysts may be present. The tumor may invade into the renal vein, ureter,

or adipose tissue.

Clear cell sarcoma

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. Characteristic cytogenetic changes are present.

Thirty percent present with metastases to lymph nodes.

Rhabdoid tumor Most are well defined

and fleshy in appearance Frequent necrosis and

hemorrhage. The renal pelvis is usually

involved.

Congenital mesoblastic nephroma

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

Mesenchymal and Other Tumors

• Renal Angiomyolipoma• Lymphoma• Secondary Tumors

Renal Angiomyolipoma Range from 1-20 cm (average 9 cm).Golden-yellow appearance is common, but depends on the ratio • >fat looks like lipoma• > smooth muscle looks like leiomyoma)  Usually well-demarcated but not encapsulated. May show local "invasion" or extension into perinephric or sinus fat

Lymphoma

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

Secondary Tumors

Kidney TrumaSubcapssular hematoma Lacerated kidney

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