An association between congenital lung cysts and PPB has been reported, although cytogenetic and molecular studies can help distinguish the nonneoplastic congenital cystic adenomatoid malformation from PPB.[33,34,35,36,37] Comparative genomic and fluorescent in situ hybridization methods have identified gain of chromosome 8q as the main recurrent chromosomal abnormality in pleuropulmonary blastoma.[38,39] A family history of cancer in close relatives has been noted for many young patients affected by this tumor.[40,41] In addition, PPB has been reported in siblings. There has been a reported association between PPB and cystic nephroma.[43,44]
The tumor is usually located in the lung periphery, but it may be extrapulmonary with involvement of the heart/great vessels, mediastinum, diaphragm, and/or pleura.[36,45] The International Pleuropulmonary Blastoma Registry identified 11 cases of Type II and Type III PPB with tumor extension into the thoracic great vessels or the heart. Radiographic evaluation of the central circulation should be performed in children with suspected or diagnosed PPB to identify potentially fatal embolic complications. The tumors may recur or metastasize, in spite of primary resection.[29,32] The cerebral parenchyma is the most common metastatic site. Responses to chemotherapy have been reported with agents similar to those used for the treatment of rhabdomyosarcoma, and adjuvant chemotherapy may benefit patients with Type I PPB by reducing the risk of recurrence.[31,47] Achieving total resection of the tumor at any time during treatment is associated with improved prognosis. Chemotherapeutic agents may include vincristine, cyclophosphamide, dactinomycin, doxorubicin, and irinotecan. High-dose chemotherapy with stem cell rescue has been used without success. Radiation, either external beam or P-32, may be used when the tumor cannot be surgically removed. Data from the International Pleuropulmonary Blastoma Registry suggest that adjuvant chemotherapy may reduce the risk of recurrence.
Evidence suggests a close histologic relationship between a Type 4 cystic adenomatoid malformation and a Type I PPB.[50,51] Complete surgical lobectomy is adequate treatment for these patients, but close observation is recommended.
There are no standard treatment options. Current treatment regimens have been informed by consensus conferences. The rare occurrence of these tumors makes recommending treatment difficult. Some general treatment considerations from the Pleuropulmonary Blastoma Registry include:
- Type I: Surgery alone for select cases; adjuvant chemotherapy may decrease recurrences.[31,52]
- Type II and Type III: Surgery followed by chemotherapy.
An independent group of researchers has established a registry and resource Web site for this rare tumor.
Esophageal cancer is rare in the pediatric age group, though it is relatively common in older adults. Symptoms are related to difficulty in swallowing and associated weight loss. Most of these tumors are squamous cell carcinomas, though sarcomas can also arise in the esophagus. The most common benign tumor is leiomyoma. Diagnosis is made by histologic examination of biopsy tissue.