Lung tumor
Other malignancies
Pleuropulmonary blastoma

Author: Erdener Özer, M.D., Ph.D. (see Authors page)
Editorial Board Review: Andrey Bychkov M.D., Ph.D.

Revised: 14 April 2017, last major update March 2017

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed Search: pleuropulmonary blastoma
Cite this page: Pleuropulmonary blastoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungtumorPPB.html. Accessed April 28th, 2017.
Definition / general
  • Pleuropulmonary blastoma (PPB) is a rare, primitive primary neoplasm of the thorax in young children
  • The tumor, which is often but not always associated with cystic lung lesions, may arise in pulmonary parenchyma, the mediastinum and pleura
  • It was initially proposed to be a distinct entity in 1988 (Cancer 1988;62:1516)
  • An international registry has been established (ppbregistry.org)
Essential features
  • Three subtypes of PPB exist (Types I, II and III), and are a continuum from the least to most malignant lesions (Cancer 2015;121:276, Pediatr Dev Pathol 2015;18:504)
    • Type I is multicystic; it is now considered the same clinical and pathologic entity as CPAM (congenital pulmonary airway malformation) type IV (Neonatology 2017;111:76)
    • Type II shows thickening areas (nodules) within this cystic lesion
    • Type III shows solid masses
Terminology
  • PPB
  • Pneumoblastoma
  • Mesenchymal cystic hamartoma
  • Cystic mesenchymal hamartoma
  • Pulmonary rhabdomyosarcoma
  • Rhabdomyosarcoma in lung cyst
  • Pediatric pulmonary blastoma
ICD-10 coding
  • M8973/3
Epidemiology
  • PPB is encountered in childhood, mostly in the first years of life (90% are between 0 - 2 years old)
  • Type I may be found in very young children (birth to 2 years of age)
  • Types II and III tend to be found after 2 years of age (Pediatr Dev Pathol 2015;18:504)
Sites
  • PPB may arise in the lung, mediastinum and pleura
Pathophysiology
Etiology
  • PPB is associated with PPB family tumor and dysplasia syndrome in 33% of cases
  • Many of these patients have a mutation of the DICER1 gene (Cancer 2015;121:276)
Clinical features
  • Children usually present with difficulty breathing or other respiratory problems including persistent pneumonitis, coughing or atelectasis
  • 10% may also present with multilocular cystic nephroma and very rarely, Wilms tumor
Diagnosis
  • MRI or CT can help diagnose, but biopsy is suggested
Radiology description
Prognostic factors
  • The prognosis of PPB, especially Types II and III is poor because of frequent relapses and distant metastases which are often seen in the brain and bone (Pediatr Pulmonol 2015;50:698)
Case reports
Treatment
  • At present, the treatment of PPB is multimodal and includes surgery, chemotherapy or radiation therapy
  • The combination depends on the type and aggressiveness of the disease (Pediatr Pulmonol 2015;50:698)
Gross description
  • Type I PPB is a peripherally located, multicystic and thin walled structure
  • Type II PPB is a mixed solid and cystic tumor characterized by variable thickened or nodule-like areas
  • Type III PPB is characterized by a well circumscribed, mucoid, white-tan solid mass attached to the pleura and involves a lobe or entire lung; necrosis and hemorrhage may be present in the friable areas
Gross images

Images hosted on PathOut server:

Contributed by Erdener Özer, M.D., Ph.D.:

Type III PPB characterized
by well circumscribed,
whitish tan solid tumor



Case of Week #166

Type III PPB



Images hosted on other servers:

Type I PPB has multiloculated cyst
filled with scanty clear serous fluid

Pleuropulmonary Blastoma

Microscopic (histologic) description
  • Type I PPB is a peripherally located, multicystic and thin walled structure
  • Type II PPB is a mixed solid and cystic tumor with variable thickened or nodule-like areas
  • Type III PPB is an apparently heterogeneous tumor composed of one or more of the following elements:
    • Primitive blastema-like small cells with hyperchromatic nuclei, high nuclear to cytoplasmic ratio and abundant mitoses
    • Spindled and ovoid cells embedded in a myxoid stroma
    • Nodules of immature or malignant chondroid elements
    • Isolated or clusters of large anaplastic cells with pleomorphic nuclei, atypical mitotic figures or eosinophilic hyaline bodies
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Erdener Özer, M.D., Ph.D.:

Types I and III PPB



Contributed by Dr. Roopa Arora:

Pleuropulmonary blastoma

SMA



Case of the Week #166:

Type III PPB: tumor composed of primitive, undifferentiated blastema cells and sarcomatous elements of different types of differentiation



Images hosted on other servers:

Pleuropulmonary Blastoma

Pleuropulmonary Blastoma

Cytology description
  • Cellular smear with both dispersed single cells and cohesive aggregates (Arch Pathol Lab Med 2000;124:416)
  • Uniform cells (small round blue cells) may lack cytoplasm, typically display nuclear molding with round or oval nuclei containing darkly stained fine chromatin
  • Scattered malignant giant cells have more abundant cytoplasm with indistinct edges and more dispersed chromatin
  • Some malignant cells may be spindled with high N/C ratios, eosinophilic cytoplasm and irregular nuclear membranes
  • There is no evidence of rosette or glandular formation (Journal of Clinical and Diagnostic Research 2011;5:1656)
Cytology images
Images hosted on other servers:

Papanicolaou-stained aspirated tumor cells:
A) Dispersed single cells and cohesive aggregates
B-C) Cells with round or oval nuclei, darkly stained fine chromatin, and devoid of cytoplasm
D) Scattered malignant giant cells
E) A few malignant cells with more spindled contours and high nuclear-cytoplasmic ratios

Positive stains
Differential diagnosis