Kidney tumor - adult malignancies
Benign (usually) adult tumors
Cystic nephroma

Author: Pallav Gupta, M.D. (see Authors page)

Revised: 1 February 2016, last major update Janaury 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Cystic nephroma [title] kidney
Definition / General
  • Unilateral, solitary and multiloculated benign tumor with small non-communicating cysts containing clear colorless fluid; cysts have flat to hobnail epithelial lining
  • Also called multilocular renal cyst
  • Part of a spectrum of tumors that fall under the heading renal epithelial and stromal tumor which includes mixed epithelial and stromal tumor (Am J Surg Pathol 2009;33:72, Am J Surg Pathol 2007;31:489, Arch Pathol Lab Med 2006;130:80)
Essential Features
  • Multilocular non-communicationg cysts
  • Intervening septae does not show renal parenchuma, blastema or clear cells
Epidemiology
  • Children less than 5 years old (usually boys) and adults ages 40 - 69 years
  • F:M ratio is 8:1
Clinical Features
  • Patients usually asymptomatic, may have abdominal mass or obstructive symptoms
  • Pleuropulmonary blastoma can be seen in these patients and in their families
Case Reports
Treatment
  • Partial nephrectomy
Gross Description
  • Lesion can be focal or can replace the entire renal parenchyma
  • Large (5 - 10 cm), unilateral and solitary multiloculated tumor composed of multiple non-communicating thin-walled cysts of varying size that are filled with clear fluid
  • Sharply demarcated from adjacent kidney by thick fibrous capsule
  • Surface is nodular
  • No solid areas or necrosis is seen
Gross Images

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Multiple cystic structures

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Tumor of upper pole



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Multiple thin walled cysts

Micro Description
  • Cysts lined by flat / cuboidal / hobnail cells separated by fibrous septa that may have an ovarian stroma-like appearance or can be pauicellular
  • No renal parenchyma (present in polycystic disease) or blastema / embryonal elements (present in cystic partially differentiated nephroblastoma) or nests of clear cells (seen in clear cell carcinoma) are present within the cyst septae
  • The stroma may contain smooth muscle, skeletal muscle, cartilage or microscopic cysts lined by bland cuboidal cells that appear to be abortive tubules
Micro Images

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Only mature elements

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Cysts separated by septa

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Epithelial cells

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Nuclear enlargement



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Small and large cysts

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Tubular epithelium

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Fibrous stroma

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Thin fibrous septa

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Flattened epithelium

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Multiple cystic spaces

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CK19+

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Various stains

Cytology Description
Positive Stains
Electron Microscopy Description
  • Long cilia and other features of collecting tubules in cyst lining
Differential Diagnosis