Pleuropulmonary Blastoma (PPB)

Epidemiology and Etiology:

· Birth to 6y

· Type I prenatal to 2y

· May progress from type I to type III

Common sites:

·

Gross features:

· Type I (early stages):

· Entirely cystic

· Unifocal or multifocal

· Adjacent to or involving pleura

· Type II:

· Cystic and solid

· Type III:

· Purely solid

Histologic features:

· Tell-tale population of small primitive mesenchymal cells beneath benign epithelial cyst lining

· Small nodules of immature cartilage maybe

· Type I:

· Multicystic structure with delicate septae

· Type III:

· High-grade sarcoma

· Rhabdomyomatous differentiation maybe

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· Trisomy 8 (nonspecific but relatively consistent in PPB)

· CCAM does not show trisomy 8

· 75% sporadic

· 25% genetic predisposition

·

Other features:

· Type 1 (cystic) PPB is indistinguishable from CCAM in clinical presentation and imaging

· Type I PPB and type 4 CCAM may be difficult or impossible to distinguish from eachother

· Entire cyst should be put through to look for blastemal elements

· Thought to be a progression from type I to type III

· Genetic cases (25%)

· Cystic nephroma

· Small bowel polyps

· Ovarian stromal-cell tumours

· Gonadal germ cell tumours

· Childhood sarcomas

· Malignancies in other organs

References:

· Silverberg SG, DeLellis RA, Frable WJ, LiVolsi VA, Wick MR. Silverberg's Principles and Practice of Surgical Pathology and Cytopathology: 2-Volume Set. 4th ed. Churchill Livingstone; 2005:2656.