Other tumors
Pleuropulmonary blastoma

Topic Completed: 1 May 2014

Minor changes: 1 March 2019

Copyright: 2003-2019,, Inc.

PubMed Search: Pleuropulmonary blastoma[TI] full text[sb]

Vaidehi Avadhani, M.D.
Page views in 2019: 493
Page views in 2020 to date: 196
Cite this page: Avadhani V. Pleuropulmonary blastoma. website. Accessed May 26th, 2020.
Definition / general
  • Malignant tumor with a cystic / sarcomatous appearance arising in lung or less commonly in parietal pleura
  • Also called pulmonary blastoma of childhood, pneumoblastoma
  • Defined in 1988 by Manivel et al. (Cancer 1988;62:1516)
  • Tumor of infancy and childhood
  • Type I PPB are diagnosed in younger children (median age: 9 months)
  • Type II and III are seen in older children (type II: median age 36 months, type III: median age 42 months)
  • No gender preference
  • Postulated to arise from primitive mesenchymal cell - abnormally regulated mesenchymal cells proliferate and secrete growth factors that promote proliferation of proximate epithelial cells, leading to formation of cysts (Am J Surg Pathol 2008;32:282)
Clinical features
  • First 12 - 18 months of life: respiratory distress or pneumothorax
  • Ages 2 - 4 years: fever, chest pain and cough (cystic lesion often misdiagnosed as pneumonia / abscess)
  • Type I PPB does not have any distinctive features to differentiate it from a developmental lung cyst on imaging - pathologic examination is the only way to establish the diagnosis so high clinical suspicion is paramount in correct diagnosis
  • Children presenting with pneumothorax, multifocality, family history of lung cysts, PPB, rhabdomyosarcoma, nodular hyperplasia or carcinoma of thyroid gland, hamartomatous intestinal polyps, cystic nephroma or any childhood malignancy should raise the possibility of PPB and encourage removal of lung cysts for examination
Radiology description
  • Unilateral or rarely bilateral pulmonary cysts
  • Pneumothorax may be present
  • Septal thickening or intracystic mass is a clue
Radiology images

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Large thin walled cyst

Lung cavity

Case reports
  • Type 1 PPB: surgery with possible chemotherapy
    • 5 year survival ~ 85%
  • Type 2 and type 3: surgery + chemotherapy
    • 5 year survival ~ less than 50%
Gross description
  • Solid or multiloculated cysts in continuity with pleural surface
Microscopic (histologic) description
  • Type I PPB:
    • Sections show a multicystic architecture
    • Cysts are lined by respiratory type epithelium above small primitive malignant cells
    • Some cells may show rhabdomyoblastic differentiation, with a variable cambium layer
    • Small nodules of primitive cartilage and hyalinized septal stroma may be present
  • Most important features of type I PPB:
    1. Characteristic microscopic multilocular architecture
    2. Well circumscribed border with adjacent normal lung parenchyma
    3. Layers of small primitive cells within the septa
    4. Septal lining epithelium alveolar type
    5. Association with multifocality or pneumothorax

  • Type II PPB:
    • Primitive small cells forming plaques or nodules
    • May show mixed blastematous and sarcomatous features

  • Type III PPB:
    • Solid; may be composed of blastematous or sarcomatous appearing cells
    • Foci of necrosis, hemorrhage and fibrosis may be present
Microscopic (histologic) images

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Type 1: focal mesenchymal hypercellularity

Type 1: primitive blastematous cells

Type 1: various stains

Multiple cyst-like blebs

Loose myxoid matrix

Cytology description
Cytology images

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Papanicolaou stained aspirated tumor cells

Positive stains
Negative stains
Molecular / cytogenetics description
  • Recently, heterozygous germline DICER1 mutations have been described in familial pleuropulmonary blastomas
  • Also associated with trisomy 8
Molecular / cytogenetics images

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Clinicopathological data for DICER1 mutation cases

Serum mature microRNAs in the DICER1 mutation cases

DICER1 mutations

Differential diagnosis
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