Kidney tumor



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Sean R. Williamson, M.D.

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PubMed Search: Nuclear grading (kidney)

Sean R. Williamson, M.D.
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Cite this page: Williamson SR. Grading. website. Accessed December 2nd, 2022.
Definition / general
  • Based on most malignant features in one high power field (Am J Surg Pathol 1982;6:655)
  • The high power field with greatest degree of nucleolar prominence is recommended as the main basis for grading (Am J Surg Pathol 2011;35:1134)
  • Note: every cell need not show the criteria but if most cells in one high power field show a higher grade, that grade should be used

WHO / International Society of Urologic Pathology (ISUP) grading system:
  • Replaces Fuhrman grading system (Am J Surg Pathol 2013;37:1490)
  • Grade 1: Nucleoli absent or inconspicuous and basophilic at 40x (rare)
  • Grade 2: Nucleoli not prominent at 10x but visible and eosinophilic at 40x (40% of tumors)
  • Grade 3: Nucleoli conspicuous and eosinophilic at 10x (30 - 40% of tumors)
  • Grade 4: Extreme nuclear pleomorphism, multinucleated cells, rhabdoid or sarcomatoid differentiation (15% of tumors)

Fuhrman (nuclear) grade:
  1. Small, round, uniform nuclei (10 microns), inconspicuous nucleoli, look like lymphocytes (very rare)
  2. Slightly irregular nuclei, see nucleoli at 40× only, nuclear diameter 15 microns, open chromatin (40% of tumors)
  3. See nucleoli at 10×, nuclei very irregular, diameter 20 microns, open chromatin (30 - 40% of tumors)
  4. Mitoses; bizarre, multilobated, pleomorphic cells plus grade 3 features, macronucleoli (15% of tumors)

Chromophobe carcinoma:
  • Typical Fuhrman grading may not have prognostic significance (Am J Surg Pathol 2007;31:957)
  • Alternative methods of grading have been proposed, such as:
    1. Exclusion of the pleomorphic, irregular nuclei with smudged or unclear nuclear chromatin and no nucleoli (likely degenerative in nature) and grading on remainder of the cells using the 4 tiered system (Am J Surg Pathol 2011;35:962)
    2. A unique chromophobe tumor grading system:
      1. Without nuclear crowding and anaplasia
      2. Nuclear crowding (touching nuclei) and size variation > 3 fold or
      3. Presence of frank anaplasia (nuclear polylobation or tumor giant cells, again excluding degenerative changes, Am J Surg Pathol 2010;34:1233) suggested to have higher predictive accuracy (J Urol 2011;186:2168)

Papillary carcinoma:
  • One study regarding papillary carcinoma recommends assessing nucleolar prominence based upon high power field with greatest nuclear pleomorphism (Am J Surg Pathol 2006;30:1091)
Microscopic (histologic) images

Contributed by Maria Tretiakova, M.D., Ph.D.
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Small dark nuclei

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Nucleoli are barely visible

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Nucleoli are easily seen

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Large pleomorphic nuclei

AFIP images

Grade 1 nuclei are regular with indistinct nucleoli

Grade 2 nuclei have irregular contours

Grade 3 nuclei have more irregular contours

Grade 4 nuclei

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