Lung tumor
Sarcomatoid carcinoma
Pulmonary blastoma
Editor-in-Chief: Debra Zynger, M.D.
Topic Completed: 5 December 2019
Minor changes: 15 January 2020
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PubMed Search: Pulmonary blastoma[TI] free full text[sb]
Table of Contents
Definition / general | Essential features | ICD coding | Epidemiology | Terminology | Clinical features | Sites | Pathophysiology | Etiology | Diagnosis | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review answer #1 | Board review style question #2 | Board review answer #2Cite this page: Gui H, Lamzabi I. Pulmonary blastoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumorpulmonaryblastoma.html. Accessed August 8th, 2020.
Definition / general
- Rare lung malignancy, 0.25 - 1% of lung cancers
- Biphasic components with admixed epithelium and primitive stroma
- Highly aggressive, part of sarcomatoid carcinomas (BMC Res Notes 2014;7:294, WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart, 4th Edition, 2015)
Essential features
- Peripheral solitary large mass, well circumscribed, unencapsulated
- Well differentiated glandular component and blastematous stroma
ICD coding
- ICD-O: 8972/3 - pulmonary blastoma
Epidemiology
- Most common in fifth decade
- M:F = 1:1
Terminology
- Separated from fetal adenocarcinoma (epithelium only) and pleuropulmonary blastoma (mesenchymal only) (WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart, 4th Edition, 2015)
Clinical features
- Nonspecific, 40% asymptomatic (Cancer 1991;67:2368)
Sites
- All lobes equally affected with upper lobe predominance (Lung Cancer 2011;73:127)
Pathophysiology
- Both components derived from single pluripotent cell clone (Lung Cancer 2011;73:127)
- TP53 (Hum Pathol 1996;27:1117) and CTNNB1 (Am J Surg Pathol 2004;28:921) mutations detected
Etiology
- 80% associated with smoking (BMC Res Notes 2014;7:294)
Diagnosis
- Relies on tissue histology and IHC on biopsy or surgical resection
- Preoperative biopsy shows cytology of two cell patterns
Radiology description
- Large solitary peripheral mass with variable enhancement and necrosis (Lung Cancer 2011;73:127)
- 25% endobronchial growth (Respir Med 2006;100:1174)
Radiology images
Images hosted on other servers:
Mass near hilum
Compression of vena cava
Uptake within mass
Right mass
Prognostic factors
- Poor prognosis, 5 year survival 16% (Lung Cancer 2011;73:127)
- Poor prognostic factors: tumor recurrence, metastasis at initial presentation and size > 5 cm (Lung Cancer 2011;73:127)
Case reports
- 33 year old woman who smoked with left lower lobe mass (J Radiol Case Rep 2017;11:10)
- 53 year old man with upper lobe mass (Medicine (Baltimore) 2017;96:e8918)
- 66 year old woman with smoking history presenting with a large mass in the left hemithorax (Ann Thorac Surg 2019;107:e345)
- 68 year old man with left upper lobe tumor (Case Rep Oncol Med 2015;2015:842621)
- 71 year old woman, past smoker, with tumor in lower lobe (Crit Rev Oncol Hematol 2018;125:48)
Treatment
- Surgical resection (Lung Cancer 2011;73:127)
- Chemoradiation and neoadjuvant therapy have limited responses in few cases (Lung Cancer 2011;73:127)
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
Images hosted on other servers:
Solid mass
Hemorrhagic mass
Microscopic (histologic) description
- Glandular branching tubules resembling fetal lung lined by pseudostratified columnar cells with subnuclear and supranuclear glycogen vacuoles (Lung Cancer 2011;73:127)
- Loose undifferentiated mesenchymal stroma with variable cellular atypia, possible heterologous differentiation (skeletal muscle, cartilage and bone) (Lung Cancer 2011;73:127)
- Morules and neuroendocrine cells in two thirds of cases (Cancer 1991;67:2368)
- May have germ cell tumor (J Thorac Oncol 2008;3:1185) or melanoma component (Arch Pathol Lab Med 1990;114:1076)
Microscopic (histologic) images
Contributed by Hongxing Gui, M.D., Ph.D.
Epithelial and mesenchymal components
TTF1
Vimentin
University of Michigan Virtual Slide Box
Glandular epithelium and blastematous stroma
Positive stains
- Glandular component: beta catenin (nuclear), CK7, AE1 / AE3, TTF1, CEA, synaptophysin, focal chromogranin (BMC Res Notes 2014;7:294, Lung Cancer 2011;73:127)
- Blastemal stromal component: beta catenin (nuclear), vimentin, SMA (BMC Res Notes 2014;7:294)
Negative stains
- Glandular component: vimentin (BMC Res Notes 2014;7:294)
- Blastemal stromal component: CAM 5.2, TTF1 (BMC Res Notes 2014;7:294)
Electron microscopy description
- Nuclear filaments and biotin rich products attribute to nuclear clearing (Ultrastruct Pathol 1995;19:501)
Molecular / cytogenetics description
- Exon 3 of CTNNB1 missense mutations, associated with morule formation (Am J Surg Pathol 2004;28:921, J Pathol 2003;200:214)
- 42% with TP53 mutation (Hum Pathol 1996;27:1117)
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
- 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?
- Most common in young patients < 15 years old
- Low to moderate grade tumor
- Lung counterpart of Wilms tumor
- Mostly in central location
- Associated with smoking
Board review answer #1
Board review style question #2
- What distinguishes pulmonary blastoma, shown here, from primary lung carcinosarcoma?
- Less cytologic atypia
- Fewer mitotic figures
- Less necrosis
- Less common for metastasis
- Nuclear immunostaining of beta catenin
Board review answer #2
E. Pulmonary blastoma is positive for beta catenin, which is negative in lung carcinosarcoma
Reference: Pulmonary blastoma
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Reference: Pulmonary blastoma
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