Kidney tumor

Childhood tumors

Pediatric cystic nephroma



Last author update: 10 August 2022
Last staff update: 13 October 2023

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PubMed Search: Pediatric cystic nephroma

Daniel A. Anderson, M.D., M.B.A.
Maria Tretiakova, M.D., Ph.D.
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Cite this page: Anderson D, Tretiakova M. Pediatric cystic nephroma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneytumorpediatric.html. Accessed May 19th, 2024.
Definition / general
  • Uncommon, benign, exclusively cystic neoplasm of the kidney; lacks immature nephroblastic elements or solid growth (Hum Pathol 2016;48:81)
Essential features
  • Multicystic neoplasm, often found in children under 4 years old, composed of fibrous septa and differentiated tubules
  • Correlation to DICER1 mutations
  • Excellent prognosis
Epidemiology
  • Pediatric cystic nephroma (PCN) occurs most commonly 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 germline mutations and familial pleuropulmonary blastoma (PPB), whose main phenotypic spectrum includes PPB, PCN, ovarian Sertoli-Leydig tumors and multinodular goiter and less commonly, pineoblastoma, pituitary blastoma, nasal chondromesenchymal hamartoma and medulloepithelioma (Hum Pathol 2016;48:81)
Clinical features
  • Palpable abdominal mass may be incidentally found by parents, caretakers or during routine physical examination
  • Most often unilateral but familial forms may present bilaterally (J Med Genet 2010;47:863)
Diagnosis
  • Imaging modalities (e.g., ultrasound, CT, MRI) show a multilocular cystic encapsulated mass
  • Partial or radical nephrectomy will show diagnostic 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:

Ultrasonography and CT of abdomen

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)
  • Presumed transformation to anaplastic sarcoma in rare cases; however, it is unknown whether all anaplastic sarcomas of the kidney arise from pre-existing cystic nephromas
    • Anaplastic sarcomas show presence of cysts with solid areas that may be composed of undifferentiated spindle cells with anaplastic changes, benign or malignant chondroid differentiation; less common features include blastemal-like areas, foci of rhabdomyoblastic differentiation and small islands of osteoid
    • Co-occurrence of TP53 mutation may be present with DICER1 mutation
    • Longitudinal risks for transformation, responsiveness and prognosis are unknown
  • References: Mod Pathol 2018;31:169, Mod Pathol 2014;27:1267
Case reports
  • 5 month old girl with pleuropulmonary blastoma in association with cystic nephroma and DICER1 syndrome (Radiology 2014;273:622)
  • 7 month old girl with histologic features predominately of cystic nephroma but with foci containing atypical mitotic figures and anaplastic nuclei thought to be nascent anaplastic sarcoma (Hum Pathol 2016;53:114)
  • 16 month old girl with multilocular cystic renal tumor extending into the renal pelvis and ureter (J Urol Surg 2014;1:39)
  • 2 year old girl with pediatric cystic nephroma and pleuropulmonary blastoma with mutation analysis and pedigree (BMC Cancer 2017;17:146)
  • 8 year old girl with DICER1 mutation, anaplastic sarcoma and septated renal cysts, thought to be cystic nephroma (Pediatr Blood Cancer 2016;63:1272)
  • 9 year old boy with bilateral and recurrent pediatric cystic nephroma (Can Urol Assoc J 2021;15:E290)
Treatment
  • Adequately treated by resection with excellent prognosis if completely excised (J Urol 2007;177:294)
Gross description
Gross images

Contributed by Daniel Anderson, M.D., M.B.A.

Bulging mass

Multicystic

Thin septa and fine vasculature



Images hosted on other servers:

Specimen after nephrectomy

Microscopic (histologic) description
  • Multicystic architecture with variably sized simple cysts lacking immature nephrogenic elements, solid areas and cytologic atypia
  • Cystic septa are usually hypocellular and fibrous with variable amounts of mixed inflammation and rarely differentiated tubules
    • Focally increased subepithelial cellularity may be present either due to spindle cells or inflammation
    • Wavy / ropy collagen is absent
  • 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

Contributed by Daniel Anderson, M.D., M.B.A.

Cystic nephroma

Adjacent renal parenchyma

Cystic nephroma flat

Cuboidal, hobnail, flat

Cystic nephroma with hobnailing

Positive stains
  • ER positive in subepithelial stromal cells; PCN usually shows stronger and more diffuse positivity in contrast to adult cystic nephroma (Am J Surg Pathol 2017;41:472)
Molecular / cytogenetics description
  • DICER1 is a multidomain protein with 2 type III endoribonucleases
  • PCNs usually carry DICER1 mutations, which may be somatic or germline
Molecular / cytogenetics images

Images hosted on other servers:

DICER1 protein domains and mutations

Videos

Pediatric renal tumors: molecular diagnostics and COG updates

Sample pathology report
  • Left kidney, partial nephrectomy:
    • Pediatric cystic nephroma; margins are negative (see comment)
    • Comment: Pediatric cystic nephroma is characterized by mutations in the DICER1 gene and may occur as a part of DICER1 syndrome. Clinical correlation and correlation with germline DICER1 mutation analysis is recommended.
Differential diagnosis
Board review style question #1

A 2 year old boy with metastatic pineoblastoma was noted to have a palpable kidney mass. CT imaging showed a low attenuating cystic mass arising from the left kidney. Partial nephrectomy was performed and showed the above morphology on H&E. Given the findings, what syndromic condition needs to be considered?

  1. Denys-Drash Syndrome
  2. DICER1 syndrome
  3. Hereditary retinoblastoma
  4. Von Hippel-Lindau (VHL) syndrome
Board review style answer #1
B. DICER1 syndrome. The image shows features of pediatric cystic nephroma. DICER1 syndrome is characterized by an increased risk of developing pleuropulmonary blastoma, multinodular goiter, pediatric cystic nephroma, Sertoli-Lydig cell tumors and embryonal rhabdomyosarcoma. Less commonly, DICER1 mutations have been documented in pineoblastoma, pituitary blastoma, nasal chondromesenchymal hamartoma and medulloepithelioma, among others (Acta Neuropathol 2014;128:583, Acta Neuropathol 2014;128:111, Hum Genet 2014;133:1443, Eye (Lond) 2013;27:896).

Hereditary retinoblastoma is associated with pineablastoma and retinoblastoma. VHL is associated with hemangioblastomas, pheochromocytomas, renal cell carcinomas and endolymphatic sac tumors. Denys-Drash syndrome is a WT1 related Wilms tumor syndrome and associated with disorders of sexual development and Wilms tumor.

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Reference: Pediatric cystic nephroma
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