Abstract

Pleuropulmonary blastoma is a rare and aggressive childhood tumor of mesenchymal origin. It has a poor prognosis and mainly classified as cystic (type 1), mixed type (type 2), and solid (type 3). Herein, we present two cases of pleuropulmonary blastoma type 3 presenting with pneumothorax, a rare clinical presentation of pleuropulmonary blastoma, which was successfully treated with surgery.

Pleuropulmonary blastoma (PPB) is a rare tumor with a poor prognosis which often affects children under six years of age and is believed to be disembryogenic.[1] It may be of pleural or pulmonary origin, or both.[2] In certain cases, the origin cannot be determined.[2] Although rare, it is still the most frequent primary lung malignancy in childhood.[3] Pleuropulmonary blastomas are mainly classified as cystic (type 1), mixed type (type 2), and solid (type 3).[4,5] They may result in local relapse and distant metastasis[3] and is a part of a tumor spectrum related to DICER1 gene mutation.[3] It has been also shown to be linked with a disorder of the long arm of chromosome 8.[1]

In this report, we present two cases of PPB type 3 presenting with pneumothorax, a rare clinical presentation of PPB, which was successfully treated with surgery.

Case Presentation

Case 1- A 3 2-month-old m ale c hild w as a dmitted to the emergency department with severe stomach pain and fever. A right total pneumothorax was detected on chest X-ray, when no respiratory sounds were heard on the right side, and a chest tube was inserted. Clinical symptoms of the patient relieved following the insertion of the chest tube and a giant bulla type image was detected on thoracic computed tomography (CT). A written informed consent was obtained from each parent and the patient underwent video-assisted thoracoscopic surgery (VATS) and the bulla was removed from the thorax with complete excision. The patient presented with sudden high fever and coughs during the fifth month of follow-up, and a large opacity on the right side was detected on chest X-ray (Figure 1). Thoracic CT revealed fluid collection with regular limited density on the right side. A VATS was initiated; however, right thoracotomy was switched due to severe adhesions and possible surgical complications and poor health status. During thoracotomy, a mass, which was considered lung initially, was observed toward the right lower lobe. The lesion was controlled and it was observed to be a mass originating from the pleural base covered with a thin and fragile capsule. The lesion was completely removed from the diaphragmatic region in which it originated. However, it was not possible to remove the fragile lesion as a single piece. The patient was discharged five days later without any complications.

Figure 1: (a) First application, a giant bulla on thoracic CT. (b) First surgery, resection by endoscopic linear stapler of giant bulla. (c) Second application, second surgery for mass, resected tumor tissue (d) Surgical specimen (Case 1).
CT: Computed tomography.

Case 2- A 12-month-old female patient was admitted to our institution with a foreign body aspiration diagnosis, after she started crying while playing with a balloon filled with fluid. A chest tube was inserted in the patient after detecting total pneumothorax on chest X-ray. No foreign body was detected in the rigid bronchoscopy. A cavitary lesion with a diameter of approximately 12 mm was observed on CT in the right chest upper lobe anterior segment. A written informed consent was obtained from each parent and a right thoracotomy was performed, and an air leak focus was observed in the right lung upper lobe and a linear stapler was applied. At six-month follow-up, the patient was hospitalized after detecting a rightsided distinctive opacity on chest X-ray and thoracic CT revealed findings compatible with the presence of a pneumothorax 4 cm in diameter in the anterior section of the right hemothorax and a 5×7-cm lesion in the vicinity of this air appearance for which fluid mass distinction was unable to be made. A lesion with indistinct borders and a cystic appearance was observed in the thoracic cavity after right thoracotomy was performed. The primary origin of the mass remained undetermined. The lesion was separated from the thymus surface via wedge resection. Similarly, the parenchyma of the lung was subjected to wedge resection (Figure 2). The patient was discharged after chest tube removal with suggestions.

Figure 2: (a) First application with pneumothorax. (b) Cavitary lesion on right upper lobe. (c) Second application, an opacity seen in right superior lobe on chest X-ray. (d) a 5×7-cm lesion (Case 2).

Histopathological examination showed neoplastic tissues consisting of spindle and some pleomorphic cells. Cystic areas were only observed as microscopic foci and tumoral tissue was completely solid. Neoplastic cells showed diffuse vimentin positivity. There was focal desmin and myogenin positivity showing rhabdomyoblastic differentiation. The result was reported as PPB type 3 in both patients.

Discussion

The majority of tumors of the thorax in childhood are comprised of metastases of malignancies outside the thorax.[2] Primary malignant thoracic tumors account for less than 1% of all pediatric malignancies.[6] Pleuropulmonary blastoma was first described in 1988 based on presentation of the histopathological and clinical characteristics of this mesenchymal cell-based disease.[2] Later on, the International Pleuropulmonary Blastoma Registry (IPPBR) and European Cooperative Study Group for Pediatric Rare Tumors (EXPERT) studies collected data on this rare disease and put forth definitions related to the diagnosis, treatment, and follow-up of PPB.[1,7]

Clinical presentation of PPBs include complaints resembling respiratory system infections such as coughing, fever, and shortness of breath.[7] Therefore, patients are often misdiagnosed with upper respiratory tract infections.

Surgery is the primary method of treatment. Thoracotomy is performed and total mass excision is recommended. However, many studies have shown that subtotal resection is also acceptable. Although there is currently no established chemotherapy regimen, different protocols with doxorubicin have been used in the treatment. In addition, the effect of radiotherapy on PPBs has not been determined, yet.[1,7] However, the mean disease-free survival (DFS) and overall survival (OS) have been more clearly defined in recent years. Five-year DFS and OS rates have been reported as 82% and 91%, respectively for type 1 disease, 59% and 37%, respectively for type 2 disease, and 71% and 53%, respectively for type 3 disease.[7]

In the literature, there are patients similar to our cases who underwent surgery following the presentation with pneumothorax complaints without histopathological or intraoperative detection of a tumor, but in whom a PPB was diagnosed about six months after surgery and underwent a further surgical treatment.[8] In such cases, cystic lung disease may be a precursor of PPB.[8] A lthough it h as b een i ndicated in both EXPERT and IPPBR studies that all three types can transform into one another and cystic lesions are indicated in some cases as precursors, the exact mechanisms remain unclear. Further studies are, therefore, warranted.

In conclusion, pleuropulmonary blastoma should be kept in mind in the early stage for pediatric cases presenting with spontaneous pneumothorax complaints and close follow-up on a monthly basis is recommended for these patients, since pleuropulmonary blastoma may grow rapidly within six months.

Declaration of conflicting interests
The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Funding
The authors received no financial support for the research and/or authorship of this article.

References

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