Pulmonary blastoma

Lung tumor
Sarcomatoid carcinoma
Pulmonary blastoma

Authors: Hongxing "Simon" Gui, M.D., Ph.D., Ihab Lamzabi, M.D.

Editor-in-Chief: Debra Zynger, M.D.

Topic Completed: 5 December 2019

Revised: 15 January 2020

Copyright: 2003-2020, PathologyOutlines.com, Inc.

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

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Table of Contents

Cite this page: Gui H, Lamzabi I. Pulmonary blastoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungtumorpulmonaryblastoma.html. Accessed March 28th, 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
- 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

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

E. Smoking is a risk factor of pulmonary blastoma

Reference: Pulmonary blastoma

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Board review style question #2

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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