Pleuropulmonary blastoma the so-called pulmonary blastoma of childhood

Abstract

The authors studied 11 pediatric intrathoracic neoplasms that share clinicopathologic features and constitute a specific tumor in children. These neoplasms were intrapulmonary, mediastinal, or pleural-based masses. A common histologic feature was the presence of small, primitive cells with blastematous qualities separated by an uncommitted stroma. Focal rhabdomyosarcomatous, chondrosarcomatous, and liposarcomatous differentiation was observed. Epithelial components had bland cytologic features and probably represented entrapped benign epithelium and/or mesothelium. The prognosis for these patients was grave; seven patients died of their disease 5 months to 2 years after diagnosis. Two patients have survived disease-free for 10 and 12 years after diagnosis. Two recent cases are alive 14 and 32 months after diagnosis. This neoplasm constitutes a distinct entity which has been reported in the literature as pulmonary blastoma in children. It differs from pulmonary blastoma in adults because of its variable anatomic location, primitive embryonic-like blastema and stroma, absence of a carcinomatous component, and potential for sarcomatous differentiation. The designation of pleuropulmonary blastoma is suggested by the authors for these intrathoracic neoplasms of childhood rather than pulmonary blastoma for histogenetic and anatomic reasons. The clinicopathologic features, immunophenotypic and ultrastructural characteristics, possible histogenesis, and differential diagnosis of these neoplasms from other thoracopulmonary tumors in children serve as the basis for this report.

Pulmonary cysts in early childhood and the risk of malignancy

“…41 At approximately the same time that CPAM type 4 was being introduced into the literature, so also was the spectrum of cystic to solid PPB. 8,28,49 As discussed above, the initial manifestation of PPB is a It is important to emphasize that cystic PPB is distinct from types 1 and 2 CPAM. PPB is not a pre-existing CPAM which has undergone ''malignant transformation,'' a persistent misconception in the literature.…”

“…8,28,57 It appears to be the pulmonary analog of more common developmental neoplasms of childhood, such as Wilms tumor (nephroblastoma), hepatoblastoma, neuroblastoma, embryonal rhabdomyosarcoma and medulloblastoma, all named because of their histologic resemblance to corresponding embryonal tissues. Like these other pediatric malignancies, most cases of PPB (94%) present in children less than 6 years of age.…”

“…The information presented on PPB has been collected and analyzed since the late 1980s by the International PPB Registry (IPPBR) (www.ppbregistry.org) comprised of physicians involved in the initial description of this rare malignancy. 8 The Registry currently follows more than 220 pathology-confirmed cases of PPB. Data from these observations can inform the cyst management decision regarding the likelihood of malignancy and the specific, albeit rare, populations in which malignancy can be predicted to occur.…”

Gain of chromosome 8q is a frequent finding in pleuropulmonary blastoma

“…All initial diagnoses were confirmed and the tumors were classified into pleuropulmonary blastoma types 1, 2, and 3, according to the gross specimen description and microscopic analysis. 1 Routine immunohistochemical analysis was performed on 4-mm thick tissue sections from a representative block of each of the tumors, using antibodies to myoglobin, myogenin, vimentin, pankeratin, actin, CD34, smooth muscle actin, desmin, S100, and MyoD1. Incubation of slides was performed using a standard avidin-biotin-complex method.…”

“…The latter tumor consists of malignant epithelial and mesenchymal components, whereas in pleuropulmonary blastoma only the mesenchymal component is malignant, the epithelial component being regarded as entrapped elements. 1 The mesenchyme may be undifferentiated or may show rhabdomyomatous, chondroid, or fibrosarcomatous differentiation. Generally, three gross types of pleuropulmonary blastoma have been distinguished: type 1, consisting entirely of multiple cysts; type 2, consisting of solid and cystic areas; and type 3, entirely composed of solid tumor tissue.…”