Ann Thorac Surg 2002;73:1572-1575
© 2002 The Society of Thoracic Surgeons
Original article: general thoracic
Pulmonary blastoma: medium-term results from a regional center
Afzal Zaidi, FRCS*a,
Vipin Zamvar, FRCS(CTh)a,
Fergus Macbeth, FRCRa,
Allen R. Gibbs, FRCPathb,
Nihal Kulatilake, FRCSa,
Eric G. Butchart, FRCSa
a Department of Cardiothoracic Surgery, University Hospital of Wales, Heath Park Cardiff, United Kingdom
b Department of Histopathology, Llandough Hospital, Cardiff, United Kingdom
Accepted for publication February 4, 2002.
* Address reprint requests to Dr Zaidi, Department of Cardiothoracic Surgery, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK
e-mail: afzalzaidi{at}compuserve.com
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Abstract
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Background. Pulmonary blastomas are rare lung tumors that morphologically resemble fetal pulmonary structure and can exist in two forms, biphasic and monophasic. We reviewed our experience over a 12-year period with emphasis on the clinical features, management, and outcome.
Methods. Patients with a diagnosis of pulmonary blastoma from January 1988 to July 1999 were identified from the database of the Department of Histopathology, Llandough Hospital, Cardiff. Specimens had been obtained from bronchoscopy, fine-needle aspiration, trucut biopsy, and thoracotomy.
Results. Six patients were identified from 2,720 histologically proven lung cancers (0.2%). Median age was 35.5 years and sex ratio was equal. Overall, 4 patients underwent resection and are all alive (median, 43.5 months). Three of these had advanced tumors at presentation (stage IIIb or IV), two of which were successfully downstaged with neoadjuvant chemotherapy, and the third treated with postoperative radiotherapy. Nonresected cases succumbed at a median of 5.5 months.
Conclusions. Although pulmonary blastomas are rare, those affected represent a group of patients with advanced tumors for whom a coordinated approach from both oncologists and surgeons can achieve excellent medium-term results.
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Introduction
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Pulmonary blastomas are rare lung tumors composed of immature mesenchyme or epithelium that morphologically resemble fetal lung [1]. This tumor was first described in detail by Barnard [2] in 1952 who named it pulmonary embryoma. The term pulmonary blastoma was first used by Spencer in 1961 in the belief that these tumors were analogous to nephroblastomas [3]. However, in 1988 pleuropulmonary blastoma of infancy was classified separately from pulmonary blastoma, as it was accepted that the former was a high-grade sarcomatous malignancy of infancy, with epithelial components representing entrapped epithelium [4]. The remaining pulmonary blastomas have been divided into two groups: biphasic tumors (containing both epithelial and mesenchymal elements) and monophasic or well-differentiated fetal adenocarcinoma (containing epithelial elements only) [5]. Recently the latter has been classified under adenocarcinoma in the third World Health Organization classification of lung cancer.
Because the majority of patients reported in the literature have been single or double case reports [6–8] we sought to review our experience of this tumor in a single institution during a 12-year period with emphasis on the clinical features, management, and outcome.
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Material and methods
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Patients with a diagnosis of pulmonary blastoma from January 1988 to July 1999 were identified from the database of the Department of Histopathology, Llandough Hospital, Cardiff. Specimens had been obtained from bronchoscopy, fine-needle aspiration, trucut biopsy, and thoracotomy. Histopathologic diagnosis was confirmed by two experienced pathologists specializing in pulmonary histopathology. Biphasic pulmonary blastomas were defined as those tumors containing malignant mesenchyme and epithelium in which one or both components mimic fetal lung between 10 and 16 weeks’ gestation [9]. Well-differentiated fetal adenocarcinomas were defined as monophasic tumors containing neoplastic well-ordered glandular epithelial elements showing an endometrioid pattern and resembling embryonic lung [5].
Clinical staging was defined in accordance with the revised International System for Staging Lung Cancer [10]. Survival times were measured from the time of diagnosis.
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Results
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Six patients with pulmonary blastoma were identified from this period. Two thousand seven hundred twenty lung cancers were diagnosed in the histopathology department during this same period, giving an incidence of 0.2% for all histologically verified lung cancers. Histologic features, stage, treatment, and outcome are summarized in Table 1.
The median age at presentation was 35.5 years, with equal sex incidence. Five tumors occurred in smokers (mean consumption, 14.8 pack years), and presentation was generally with dyspnea, hemoptysis, or cough. One tumor was discovered on a routine chest roentgenogram in an asymptomatic patient (case 4). In all patients a mass was visible on the chest film. Histologically, three blastomas were biphasic and three were monophasic (well-differentiated fetal adenocarcinoma).
Patients 1 and 2 were inoperable due to esophageal involvement and hepatic metastases, respectively. Patient 3 underwent an intrapericardial pneumonectomy, but unexpectedly, tumor was seen within the inferior pulmonary vein, confirmed histologically. He underwent postoperative radiotherapy to the mediastinum. Nine months later he presented with a visual field defect due to a solitary cerebral metastasis. This was treated by resection followed by cranial irradiation. Patients 5 and 6 were initially considered inoperable due to malignant pleural effusion and left atrial involvement, respectively. Neoadjuvant chemotherapy successfully downstaged the tumors before surgical excision (Fig 1).
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Fig 1. Preoperative computed tomographic scans of a 27-year-old woman (patient 6) with a stage IIIb pulmonary blastoma taken (A) before and (B) after neoadjuvant chemotherapy with mitomycin, ifosfamide, and carboplatin. There is tumor present within the left atrium (A), which has disappeared after two cycles of chemotherapy (B). An intrapericardial pneumonectomy was subsequently performed.
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Comment
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Pulmonary blastomas are rare, and much of the world literature derives from reviews of isolated case reports [11] or the experience of multiple centers during several decades [1]. Therefore, we sought to review our experience with this tumor in a single teaching hospital (with a large referral base) during a 10-year period. Before 1988 pleuropulmonary blastoma of childhood was also included in this group by some authorities, leading to discrepancies between investigators in the perceived demographics and clinical features of this disease. Since 1988, and in this review, pleuropulmonary blastoma has been excluded. The incidence of 1 in 450 histologically proven lung cancers may not seem as rare as would be expected given the paucity of the literature, thus variation in histopathologic diagnosis and classification is likely to be important. In a retrospective review of 380 patients with pulmonary adenocarcinoma, Tamai and colleagues [12] discovered two pulmonary blastomas that had been misclassified, an incidence of 0.5%. This review reflects the incidence of histopathologically diagnosed lung cancer from within the Cardiff area as well as being a tertiary referral center for surrounding areas.
Pulmonary blastomas are tumors that affect a younger age group of patients than the common pulmonary malignancies, with a median age of 35.5 years (range, 23 to 67 years). This is very similar to the findings of Koss and colleagues [1] and Larsen and Sorensen [11] (Table 2).
In our series there appears to be an association with cigarette smoking. Koss and associates, the only researchers to document the smoking habits in their review, also found a strong correlation with cigarette smoking (80%) [1]. This implies that the latency of this tumor in relation to smoking is much shorter than for other smoking-related lung cancers. The equal sex ratio and equal incidence of well-differentiated fetal adenocarcinoma and biphasic forms are also similar findings in that study.
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Table 2. Comparative Clinical Features of Pulmonary Blastoma With Respect to Histologic Type in This Series and That of Koss et al [1] and Larsen et al [11]
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It is noteworthy that our series arises from a regional general thoracic surgical practice, in contrast to that of Koss and colleagues [1] from the Armed Forces Institute of Pathology, Washington, DC, which represents a supraregional service. This may explain why Koss mainly reported stage I tumors, whereas five of six tumors in our series were advanced (stage IIIb or IV) at the time of presentation. Three of these patients underwent surgical resection, in one case followed by radiotherapy (its advanced stage was only discovered at operation), and in 2 patients with neoadjuvant chemotherapy, which successfully downstaged the tumor before surgical resection. These 3 patients with advanced cancers, who underwent surgical resection, are all alive and well at a median of 30 months. All 4 operated patients are alive at a median of 43.5 months. The two nonresected cases succumbed at a median of 5.5 months. We believe that surgical resection should be contemplated in all patients, with neoadjuvant chemotherapy used in an attempt to downstage advanced tumors before resection. During the period 3 patients received chemotherapy with three different regimens from different oncologists. In the absence of any clear guidance from the literature, regimens were selected somewhat arbitrarily. In 2 patients there was a substantial response (that led to successful resection) to regimens containing either cisplatin or carboplatin and ifosfamide. Although we cannot draw firm conclusions from this limited data, it would seem that this can be a chemoresponsive tumor, and that regimens containing these drugs should be considered. Our data do not allow us to comment on the value of radiotherapy either as a sole modality or as a postoperative adjuvant.
In this series even a solitary cerebral metastasis resected 9 months after the lung resection has not precluded a 4.5-year survival in a person who still works as a music teacher. Clearly if this patient’s well-differentiated fetal adenocarcinoma pulmonary blastoma had been misdiagnosed as an adenocarcinoma he may not have received such aggressive therapy. In both our series and that of Koss, well-differentiated fetal adenocarcinoma tumors do carry a better prognosis than adenocarcinomas and biphasic pulmonary blastomas of similar stage [10].
Thus, although pulmonary blastomas are rare, those affected by them represent a group of patients with advanced tumors for whom a coordinated approach from both oncologists and surgeons can achieve excellent medium- to long-term results.
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References
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Abstract
Introduction
