Wilms' tumor

This protocol is intended to assist pathologists in providing clinically useful and relevant information as a result of the examination of surgical specimens. Use of this protocol is intended to be entirely voluntary. If equally valid protocols or similar documents are applicable, the pathologist is, of course, free to follow those authorities. Indeed, the ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of the individual circumstances presented by a specific patient or specimen.

It should be understood that adherence to this protocol will not guarantee a successful result. Nevertheless, pathologists are urged to familiarize themselves with this document. Should a physician choose to deviate from the protocol owing to the circumstances of a particular patient or specmen, the physician is advised to make a contemporaneous written notation of the reason for the procedure followed.

The College recognizes that this document may be used by hospitals, attorneys, managed care organizations, insurance carries, and other payers. However, the document was developed solely as a tool to assist pathologists in the diagnostic process by providing information that reflects the state of relevant medical knowledge at the time the protocol was first published. It was not developed for credentialing, litigation, or reimbursement purposes. The College cautions that any uses of the protocol for these purposes involve considerations that are beyond the scope of this document.

EXPLANATORY NOTES

A: Histologic Type.-The histopathologic classification most recently published by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC) is recommended.lz However, the protocol does not preclude the use of other published classificationsolo which appear in the Atlas of Tumor Pathology, 3rd series, Fascicle 11, Tumors of the Kidney, Bladder and Related Urinary Structures as shown below.3

AJCC/UICC Histologic Classification of Renal Carcinoma

Conventional (clear cell) renal carcinoma

Papillary renal carcinoma

Chromophobe renal carcinoma

Collecting duct carcinoma

Renal cell carcinoma, unclassified

Armed Forces Institute of Pathology Histologic Classification of Renal Cell Carcinoma

Clear cell (hypernephroid) renal cell carcinoma

Granular renal cell carcinoma*

Papillary renal cell carcinoma

Chromophobe renal cell carcinoma

Collecting duct-type renal cell carcinoma

Sarcomatoid renal cell carcinoma*

Mixed-type renal cell carcinoma

Renal cell carcinoma, undifferentiated

* These histologic types of renal cell carcinoma are not included in the AJCC/UICC classification because it is argued they may not represent unique forms of differentiation. Abundant granular cytoplasm may occur in any of the following tumor types: oncocytoma, chromophobe renal cell carcinoma, papillary renal cell carcinoma, collecting duct carcinoma, and epithelioid angiomyolipoma. Sarcomatoid morphology may be manifested by any renal cell carcinoma (conventional papillary, chromophobe, or collecting duct subtypes), as well as by urethelial car*noma of the renal pelvis, and may represent a progression in tumor grade.

B: Histologic Grade-The following grading scheme for renal cell carcinoma developed by Fuhrman et al is recommended.ll However, the protocol does not preclude the use of other grading schemes.lZ 16 The system of grading should be specified in the pathologist's report.

Grade X Cannot be assessed

Grade 1 Nuclei round, uniform, approximately 10 mu m in diameter; nucleoli inconspicuous or absent

Grade 2 Nuclei slightly irregular, approximately 15 Jim in diameter; nucleoli evident

Grade 3 Nuclei very irregular, approximately 20 Fm in diameter; nucleoli large and prominent

Grade 4 Nuclei bizarre and multilobated -20 lim in diameter; nucleoli prominent, chromatin clumped

C: Operative Procedures.-A partial nephrectomy may vary from a simple enucleation of the tumor to a partial nephrectomy including variable portions of the calyceal or renal pelvic collecting system. The perirenal fat immediately overlying the resected portion of kidney but not to the level of Gerota's fascia is usually included.

D: TNM and Stage Groupings.-The TNM Staging System of the AJCC / UICC for renal cell carcinoma is recommended as followsl7:

Primary Tumor (T)*

TX Primary tumor cannot be assessed

TO No evidence of primary tumor

T1 Tumor -7.0 cm in greatest dimension, limited the kidney

T2 Tumor >7.0 cm in greatest dimension, limited the kidney

T3 Tumor extends into major veins or invades the ad renal gland or perinephric tissues, but not beyonc Gerota's fascia

T3a Tumor invades the adrenal glandt or perinephri tissues, but not beyond Gerota's fascia

T3b Tumor grossly extends into the renal vein(s) o: vena cava below the diaphragm

T3c Tumor grossly extends into the vena cava abovw the diaphragm

T4 Tumor invades beyond Gerota's fascia

* By AJCC/UICC convention, the designation "T" of the TNM classification refers exclusively to the first resection of a primary tumor The prefix symbol "p" refers to the pathologic classification of the TNM (pTNM), as opposed to the clinical classification. Pathologic classification is based on gross and microscopic examination. Therefore, pT entails a resection of the primary tumor or biopsy adequate to evaluate the highest pT category, pN entails removal of nodes adequate to validate lymph node metastasis, and pM implies microscopic examination of distant lesions. Clinical classification (cTNM) is usually carried out by the referring physician before treatment during initial evaluation of the patient or when pathologic classification is not possible.

The absence or presence of residual tumor following preoperative nonsurgical therapy (eg, chemotherapy or radiation treatment) may be described by the symbol "R" and is classified as follows:

RX Presence of residual tumor cannot be assessed

RO No residual tumor

R1 Microscopic residual tumor

R2 Macroscopic residual tumor

If residual tumor is present, its extent may be documented by the TNM classification preceded by the symbol "y" (eg, ypTl). Local recurrence following a previous resection should be classified with the prefix "r" (eg, rpTl).

^ Direct invasion of the adrenal gland, which is categorized as local extension, must be differentiated from metastatic tumor in the adrenal gland, which is categorized Ml (see "Distant Metastasis").

Regional Lymph Nodes (N): (note E)

NX Regional lymph nodes cannot be assessed

NO No regional lymph node metastasis

N1 Metastasis in a single lymph node

N2 Metastasis in more than 1 regional lymph node

^^ Laterality does not affect the N classification.

Distant Metastasis (M)

MX Distant metastasis cannot be assessed

MO No distant metastasis

E: Lymph Nodes.-Regional lymphadenectomy is not generally performed even with a radical nephrectomy. A few lymph nodes may be found in a nephrectomy spedmen in the renal hilus around the major renal vessels. Other regional lymph nodes (eg, paracaval, para-aortic, and retroperitoneal) may be submitted separately.

F: Radical Nephrectomy.-A standard radical nephrectomy specimen consists of the entire kidney, including the calyces, pelvis, and a variable length of ureter. The adrenal gland is usually removed en bloc with the kidney. The entire perirenal fatty tissue is removed to the level of Gerota's fascia, a membranous structure that is similar in consistency to the renal capsule, which encases the kidney and perirenal fat. Variable lengths of the major renal vessels at the hilus are submitted. Some lymph nodes may be nresent in the renal hilus.

References

1. St*rkel S, Eble JN, Adlakha K, et al. Classification of renal cell carcinoma. Workgroup No. 1. Cancer 1997;80:987-989.

2. Amtrup F, Hausen lB, Thybo E. Prognosis in renal cell carcinoma evaluated from histological criteria. Scand] Urol Nephrol. 1974;8:198-202.

3. Murphy WM, Beckwith JB, Farrow GM. Tumors of the adult kidney. In: Tumors of the Kidney, Bladder and Related Structure. Washington, DC: Armed Forces Institute of Fathology; 1994:98-124. At/as of Tumor Pathology; 1994:98-124. Atlas of Tumor Pathology, 3rd series, fascicle 11.

4. Angervall L, Carlstrom E, Wahlqvist L, Ahren C. Effects of clinical and morphologic variables on spread of renal cell carcinoma in an operative series. Scand J Urol Nephrol. 1969;3:134-140.

5. Bennington )L. Tumors of the kidney. In: Javadpour N, Barsky SH, eds. Surgical Pathology of Urologic Diseases. Baltimore, Md: Williams & Wilkins; 1987: 120-122.

6. Fleming S. The impact of genetics on the classification of renal carcinoma. Histopathology 1993;22:89-92.

7. Kovacs G. Molecular differential pathology of renal cell tumours. Histopathology. 1993;22:1-8.

8. Mathisen W, Muri O, Myhre E. Pathology and prognosis in renal tumors. Acta Chir Scand. 1965;130:303-313.

9. Petkovic SD. An anatomical classification of renal tumors in the adult as a basis for prognosis. I Urol.1959;81:618-623.

10. Thoenes W, Storkel S, Rumpelt HJ. Histopathology and classification of renal cell tumors (adenomas, oncocytomas and carcinomas). Pathol Res Pract. 1989;181:125-143.

11. Fuhrman SA, Lasky LC, Limas C. Prognostic significance of morphologic parameters in renal cell carcinoma. Am J Surg Pathol.1982;6:655-663. 12. Arner O, Blanck C, van Schreeb T. Renal adenocarcinoma: morphology grading of malignancy, prognosis: a study of 197 cases. Acta Chir Scand.1965; 346(suppl):1-51.

13. Hermanek P, Sigel A, Chlepas S. Histological grading of renal cell carcinoma. Eur Urol. 1976;2:189-191.

14. Siminovitch JM, Montie JE, Straffon RA. Prognostic indicators in renal adenocarcinoma. J Urol.1983;130:20-23.

15. Skinner DG, Colvin RB, Vermillion DC, Pfester RC, Leadbetter WF. Diagnosis and management of renal cell carcinoma: a clinical and pathologic study of 309 cases. Cancer. 1971;28:1165-1177.

16. Syrjanen K, Hjelt L. Grading of human renal adenocarcinoma. Scand] Urol Nephrol. 1978;12:49-SS.

17. Fleming ID, Cooper IS, Henson DE, et al, eds. AJCC Manual for Staging of Cancer. 5th ed. Philadelphia, Pa: Lippincott Raven; 1997.

George Farrow, MD; Mahul B. Amin, MD; for the Members of the Cancer Committee, College of American Pathologists

Accepted for publication August 26, 1998. From the Department of Pathology, Mayo Clinic, Rochester, Minn (Dr Farrow), and Emory University, Atlanta, Ga (Dr Amin). This protocol was developed by the Cancer Committee of the College of American Pathologists and submitted for editorial review and publication. It represents the views of the Cancer Committee and is not the official policy of the College of American Pathologists.

Reprints: Joe Schramm, College of American Pathologists, 325 Waukegan Rd, Northfield, IL 60093-2750.

Copyright College of American Pathologists Jan 1999
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