Pulmonary cystic disease may be the indication for surgery, and PPB may be an unexpected microscopic finding in the wall of a lung cyst (see Pathology of PPB, Type I, below). When cystic lung disease is the only indication for surgery, there is usually little pre-operative concern about a malignancy and resections of cysts may be incomplete. Because 25% of PPB cases occur in genetically susceptible children, PPB might be considered in advance if there is any family history of childhood cancer or dysplasia, cystic nephroma, or multifocal or bilateral lung cysts. (see Constitutional/Syndromic and Familial Disease.
More commonly, during thoracotomy for exploration of a chest mass or an unexplained infectious process, Type II or III PPB will be discovered. Pleural effusion is common, and empyema is occasionally a consideration. PPB involves pleura and lung parenchyma extensively, crossing lobar boundaries. The origin of lesions may be impossible to discern. Entire hemithoracic involvement is common. PPB tissue is often friable, necrotic and hemorrhagic. Spillage, as in Wilms' tumor, is common.
In addition to lung and pleura, PPB may invade the chest wall, mediastinum, diaphragm, superior vena cava and right atrium, or pulmonary vein and left atrium. Tan et al. Pleuropulmonary blastoma with a large embolic cerebral infarct. Pediatr Radiol 2003;33:506-8.] Hilar lymph node involvement is not common.
“Complete” resection is often reported by surgeons, but in the more extensive cases, resection may be piecemeal. Lobectomy is a common surgical result; pneumonectomy is rare. Re-expansion of remaining lung is typical. We find no cases of intra-operative death in a review of all Registry and literature cases, although the extent of disease is occasionally so massive that early post-operative death (2 - 4 days) from respiratory and circulatory insufficiency has occurred.
The importance of extent of surgical resection was addressed in the Registry’s series of 50 patients published in 1997. We could not show that the degree of resection was statistically associated with survival in univariate analysis. Type I (purely cystic) disease seems more likely to be completely resected and appears to have a greater likelihood of survival, but statistical significance was not reached, perhaps due to small numbers [Registry Publications, Priest et al 1997].
Several cases of post-biopsy, neo-adjuvant (pre-resection) chemotherapy have been reported and are summarized below (see Chemotherapy Recommendations). Tumor shrinkage of 33 - 85% has been reported after 3 - 4 months. Neo-adjuvant chemotherapy for extensive disease is used in other pediatric neoplasms such as Wilms' tumor and hepatoblastoma and is an appealing strategy. It is our hope that data collected by the PPB/DICER1 Registry may define this approach further.
Surgeons are asked to consider sending tissue to the PPB/DICER1 Registry Tissue Bank. For details, see Tissue Bank.