Kidney tumor
Childhood neoplasms
Pediatric cystic nephroma

Author: Daniel Anderson, M.D., M.B.A. (see Authors page)
Editor: Maria Tretiakova, M.D., Ph.D.

Revised: 30 January 2017, last major update January 2017

Copyright: (c) 2017, PathologyOutlines.com, Inc.

PubMed Search: pediatric cystic nephroma
Cite this page: Pediatric cystic nephroma. PathologyOutlines.com website. http://pathologyoutlines.com/kidneytumorpediatric.html. Accessed December 17th, 2017.
Definition / general
  • Uncommon, benign, exclusively cystic neoplasm of the kidney lacking immature nephroblastic elements or solid growth (Hum Pathol 2016;48:81)
Essential features
  • Multicystic neoplasm often in children under 4 years old composed of fibrous septa and differentiated tubules
  • Correlation to DICER1 mutations
  • Excellent prognosis
Epidemiology
  • Pediatric cystic nephroma (PCN) almost exclusively occurs in children younger than 4 years old, most of whom are boys (Am J Surg Pathol 2016;40:1591)
  • Familial cases have been linked to DICER1 germ line mutations and familial pleuropulmonary blastoma (PPB), whose main phenotypic spectrum includes PPB, PCN, ovarian Sertoli-Leydig tumors and multinodular goiter (Hum Pathol 2016;48:81)
Clinical features
Radiology description
  • On CT / MRI, appears as a cystic, multilocular mass, often with pseudocapsule defined as a thin rim of tissue demarcating the margin of the lesion from the adjacent renal parenchyma; may abut the renal pelvis or show protrusion / herniation into the renal pelvis (Hum Pathol 2016;48:81, Radiographics 1995;15:653)
  • Ultrasonographic findings are multiple anechoic spaces separated by thin septa (Radiographics 1995;15:653)
Radiology images

Images hosted on other servers:

Large mass occupying left side of the abdomen

Multicystic mass

Mass extending into the left renal pelvis (arrows)

Low attenuation mass with multiple separations

A, B: ultrasonography; C, D: CT abdomen

A well circumscribed huge CN in the right kidney

Prognostic factors
  • Prognosis is excellent: overall survival was 100% over a median followup of 2.4 years in one study (J Urol 2007;177:294)
  • Possible transformation to renal sarcoma, although longitudinal risks for transformation, responsiveness and prognosis are unknown (Mod Pathol 2014;27:1267)
Case reports
Treatment
  • Adequately treated by resection with excellent prognosis if completely excised (J Urol 2007;177:294)
Gross description
  • Relatively large (9 cm average diameter) cystic lesion, well circumscribed from the surrounding normal kidney
  • Multiple smooth variably sized (mm to cm) cysts with clear fluid
  • Thin septa with no expansile nodules altering cyst contours (Sebire: Diagnostic Pediatric Surgical Pathology, 1st ed, 2009)
  • Often adjacent, abutting, protruding or in direct contiguity to pelvicaliceal structures (Hum Pathol 2016;48:81)
Gross images

Images hosted on PathOut server:

Contributed by Dr. Daniel Anderson:

Various images



Images hosted on other servers:

Specimen after nephrectomy

Multiple smooth walled cysts separated by septa

Microscopic (histologic) description
  • Multicystic architecture with variably sized simple cysts lacking immature nephrogenic elements, solid areas and cytologic atypia
  • The cystic septa are hypocellular and fibrous, with variable amounts of mixed inflammation; no ovarian-type stroma is present
  • The cyst lining epithelium is flattened to cuboidal, with frequent hobnailing; no epithelial complexity (branching glands, papillary projection, cribriforming)
  • Partial or complete fibrous pseudocapsule often containing entrapped tubules and glomeruli; some tumors intermingle with normal parenchyma (Hum Pathol 2016;48:81)
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Dr. Daniel Anderson:

Cystic nephroma 2×

Cystic nephroma 2×

Cystic nephroma 4× with adjacent renal parenchyma

Cystic nephroma flat 10×

Cystic nephroma 20×: cuboidal, hobnail, flat

Cystic nephroma 40× with hobnailing



Images hosted on other servers:

Cystic nephroma

Cystic nephroma with multiple cysts

Multiple variably sized cysts

Cysts lined by layer of benign hobnail shaped epithelial cells

Edge of the multicystic
mass (arrowhead) and
adjacent compressed renal
parenchyma (arrow)

Negative stains
Molecular / cytogenetics description
  • A sizable portion of PCN carry a DICER1 mutation, either loss of function or missense mutations (Hum Pathol 2016;48:81, Mod Pathol 2014;27:1267)
  • DICER1 mutations could involve specific amino acids in the RNase IIIb domain including insertion-deletions with frameshifts, nonsense mutations and a c.2437-1G4A substitution involving the canonical splice site of intron 18-exon19; each of these mutations resulted in premature truncation of the DICER1 protein (deleterious truncating mutations) (Mod Pathol 2014;27:1267)
Differential diagnosis