PPB is subdivided into three pathologic subtypes, determined by laboratory examination of the surgical specimen. Type I is purely cystic in appearance with no grossly identifiable nodular disease. Type III is entirely solid disease with no grossly detectable cystic areas. There may be “cyst”-like spaces created by grossly necrotic/degenerated tumor which can be seen microscopically to be different from the “true” cysts of Type I (see below). Type II presents grossly apparent cystic and solid disease. At recurrence, Type I may have progressed to Type II or III, or Type II may have progressed to III. Regression of Type has not been observed.

• PPB Types: I, II, & III
• Progression of Type
• Type I Pathology Diagnosis and Differential Diagnosis
• Type II & III Pathology Diagnosis and Differential Diagnosis
• Differentiation from Adult Pulmonary Blastoma
• Immunohistochemistry
• Ultrastructural Findings
• Fine Needle Aspiration Cytology
• Pathology of Metastases
• Recommended Path Studies
• Special Studies/Tumor Cytogenetics
• Pathology Consultation

Surgeons are asked to consider sending tissue to the PPB/DICER1 Registry Tissue Bank. For details, see Tissue Bank.