Sarcomatoid carcinoma

Pulmonary blastoma

Editor-in-Chief: Debra L. Zynger, M.D.
Ihab Lamzabi, M.D.

Topic Completed: 5 December 2019

Minor changes: 12 May 2021

Copyright: 2003-2021,, Inc.

PubMed Search: Pulmonary blastoma[TI] free full text[sb]

Ihab Lamzabi, M.D.
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Cite this page: Gui H, Lamzabi I. Pulmonary blastoma. website. Accessed October 16th, 2021.
Definition / general
Essential features
  • Peripheral solitary large mass, well circumscribed, unencapsulated
  • Well differentiated glandular component and blastematous stroma
ICD coding
  • ICD-O: 8972/3 - pulmonary blastoma
  • Most common in fifth decade
  • M:F = 1:1
Clinical features
  • Relies on tissue histology and IHC on biopsy or surgical resection
  • Preoperative biopsy shows cytology of two cell patterns
Radiology description
Radiology images

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Mass near hilum

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Compression of vena cava

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Uptake within mass

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Right mass

Prognostic factors
Case reports
Gross description
  • Mostly peripheral large well circumscribed unencapsulated mass, average 9.1 cm (Lung Cancer 2011;73:127)
  • Lobulated with cystic, necrotic and hemorrhagic degeneration
Gross images

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Solid mass

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Hemorrhagic mass

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Hongxing Gui, M.D., Ph.D.

Epithelial and mesenchymal components



University of Michigan Virtual Slide Box

Glandular epithelium and blastematous stroma

Negative stains
Electron microscopy description
Molecular / cytogenetics description
Sample pathology report
  • Lung, right lower lobe, lobectomy:
    • Pulmonary blastoma, 9 cm, margins negative for tumor (see comment)
    • Comment: H&E sections demonstrate an admixture of malignant epithelial and mesenchymal components. Immunostains performed with adequate controls reveal that the glandular cells are strongly positive for pancytokeratin and TTF1. The stromal cells are vimentin positive. Beta catenin reveals nuclear staining in both epithelial and stromal components. The findings are consistent with the diagnosis of pulmonary blastoma, a subgroup of sarcomatoid carcinoma (WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart, 4th Edition, 2015).
Differential diagnosis
  • Fetal type adenocarcinoma
    • Epithelial component only, no blastematous stroma
  • Pleuropulmonary blastoma
    • Pediatric tumor, most diagnosed before 4 years of age
    • No epithelial component; admixture of blastematous and sarcomatoid components
    • Epithelium if seen is benign entrapped respiratory type
    • 40% with DICER1 mutation
  • Biphasic synovial sarcoma
    • Glandular component lacks TTF1
    • Focal CK, TLE positive, SS18-SSX fusion present
  • Carcinosarcoma
    • Non small cell carcinoma (squamous cell carcinoma or adenocarcinoma) and heterologous sarcomatous component
    • Older age
    • No nuclear staining of beta catenin
Board review style question #1
    Which of the following is true for pulmonary blastoma?

  1. Most common in young patients < 15 years old
  2. Low to moderate grade tumor
  3. Lung counterpart of Wilms tumor
  4. Mostly in central location
  5. Associated with smoking
Board review style answer #1
E. Smoking is a risk factor of pulmonary blastoma

Comment Here

Reference: Pulmonary blastoma
Board review style question #2
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    What distinguishes pulmonary blastoma, shown here, from primary lung carcinosarcoma?

  1. Less cytologic atypia
  2. Fewer mitotic figures
  3. Less necrosis
  4. Less common for metastasis
  5. Nuclear immunostaining of beta catenin
Board review style answer #2
E. Pulmonary blastoma is positive for beta catenin, which is negative in lung carcinosarcoma

Comment Here

Reference: Pulmonary blastoma
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