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Kidney tumours (or kidney tumors), also known as renal tumours, are tumours, or growths, on or in the kidney. These growths can be benign or malignant (kidney cancer).

Kidney tumour
Renal oncocytoma2.jpg
Micrograph of a renal oncocytoma, a type of benign kidney tumour. H&E stain.
Classification and external resources



Kidney tumours may be discovered on medical imaging incidentally (i.e. an incidentaloma), or may be present in patients as an abdominal mass or kidney cyst, hematuria, abdominal pain, or manifest first in a paraneoplastic syndrome that seems unrelated to the kidney.[1]



There are many forms of kidney tumours:

Malignant (cancerous)Edit

  • The most frequent, malignant, primary kidney cancer is renal cell carcinoma (RCC) - which has several subtypes:
    • Clear cell RCC.
    • Papillary RCC
    • Chromophobe RCC
    • Collecting duct RCC
  • Mesoblastic nephroma, a congenital tumor of the kidney's mesenchyme (i.e. connective tissue cells) detected prenatally or, more typically, during the first <4 years of life.[2]
  • Metastatic tumour, e.g. ovarian carcinoma.


Surgical complexityEdit

The RENAL Nephrometry Scoring System is used to measure the complexity of kidney tumors for surgical excision, and is estimated by CT scan as follows:[3]

Component 1 point 2 points 3 points
R (radius, maximal diameter) ≤ 4 cm > 4 and < 7 cm ≥ 7 cm
E (exophytic/endophytic) ≥ 50% exophytic < 50% exophytic Completely endophytic
N (nearness to collecting system/renal sinus) ≥ 7 mm > 4 and < 7 mm ≤ 4 mm
A (anterior/posterior locator) A descriptor of “a,” “p,” or “x” is assigned for tumour location.
L (location relative to polar lines) Entirely below lower polar or above upper polar line Mass crosses polar line 50% of the mass is across polar line, or
mass is entirely between polar lines, or
mass crosses axial midline

A higher score indicates a higher difficulty in removing the tumor surgically, potentially making nephrectomy necessary.


  1. ^ Gill IS, Aron M, Gervais DA, Jewett MA (February 2010). "Small renal mass". N. Engl. J. Med. 362 (7): 624–34. doi:10.1056/NEJMcp0910041. PMID 20164486. 
  2. ^ Gooskens SL, Houwing ME, Vujanic GM, Dome JS, Diertens T, Coulomb-l'Herminé A, Godzinski J, Pritchard-Jones K, Graf N, van den Heuvel-Eibrink MM (2017). "Congenital mesoblastic nephroma 50 years after its recognition: A narrative review". Pediatric Blood & Cancer. 64 (7). doi:10.1002/pbc.26437. PMID 28124468. 
  3. ^ Parsons, Rosaleen B.; Canter, Daniel; Kutikov, Alexander; Uzzo, Robert G. (2012). "RENAL Nephrometry Scoring System: The Radiologist's Perspective". American Journal of Roentgenology. 199 (3): W355–W359. doi:10.2214/AJR.11.8355. ISSN 0361-803X. 

External linksEdit