Extension of a Pulmonary Blastoma Into the Left Atrium

Abstract

Pulmonary tumors of embryonic origin are rare, and pulmonary blastomas are probably the most uncommon. A thorough literature search disclosed no previous reports of extension of this type of tumor into the heart. We describe a patient whose initial clinical presentation suggested an obstructive left atrial mass; however, clinical and histologic findings indicated the mass was a tumor that originated from a pulmonary blastoma that extended into the left atrium through a pulmonary vein. The unique aspect of this case is that the patient's symptoms were related to the obstructive effects of the atrial mass, not to the primary pulmonary tumor. Pulmonary tumors of embryonic origin are rare, and pulmonary blastomas are probably the most uncommon. A thorough literature search disclosed no previous reports of extension of this type of tumor into the heart. We describe a patient whose initial clinical presentation suggested an obstructive left atrial mass; however, clinical and histologic findings indicated the mass was a tumor that originated from a pulmonary blastoma that extended into the left atrium through a pulmonary vein. The unique aspect of this case is that the patient's symptoms were related to the obstructive effects of the atrial mass, not to the primary pulmonary tumor. About 10% of patients with malignant neoplasms have metastases to the heart. Of these patients, approximately 10% have clinical evidence of such metastases. Carcinomas invade the heart much more commonly than sarcomas. In up to 90% of patients with carcinomas, clinical findings are secondary to pericardial involvement, either effusion or pericardial thickening with restriction.1Bearman RM Primary leiomyosarcoma of the heart: report of a case and review of the literature.Arch Pathol. 1974; 98: 62-65PubMed Google Scholar The only tumors not reported to metastasize to the heart are primary central nervous system neoplasms. In absolute numbers, the most common neoplasms that produce cardiac metatases are lung tumors in men and breast tumors in women, followed by leukemias and lymphomas in both sexes. The specific malignancy with the most frequent cardiac involvement is melanoma, which occurs in up to 70% of patients with disseminated disease.2Roberts WC Spray TL Pericardial heart disease.Curr Probl Cardiol. 1977; 2: 1-71Abstract Full Text PDF Scopus (16) Google Scholar The mechanism of metastatic growth to the heart depends on the tumor's origin and mode of spread. Lung and breast carcinomas tend to involve the heart and pericardium by direct extension from contiguous structures or from retrograde lymphatic spread. In some cases there is direct venous extension, such as renal and hepatic carcinomas that follow the inferior vena cava into the right atrium. Hematogenous spread is unusual for carcinomas, but it is the main route of cardiac metastasis for sarcomas, lymphomas, leukemias, and melanomas.3McAllister HA Hall RJ Cooley DA Tumors of the heart and pericardium.Curr Probl Cardiol. 1999; 24: 57-116Abstract Full Text PDF PubMed Google Scholar A 45-year-old man with a history of tobacco use presented to our emergency department because of a 3-week history of increasing dyspnea, orthopnea, and paroxysmal nocturnal dyspnea with progressively severe lower extremity edema. He denied having any previous serious medical problems. Review of symptoms disclosed a 2-month history of cough with white sputum when the patient was supine. On admission, he was normotensive, had hypoxemia with oxygen saturation of 88% while breathing room air, and had tachycardia at a rate of 123 beats/min. Physical examination showed a cachectic man with temporal wasting and slight tachypnea but in no acute distress. Jugular venous distention was noted. A lung examination revealed right basilar crackles, and the left lower lung was dull to percussion with decreased tactile fremitus and decreased breath sounds. Cardiac examination disclosed regular tachycardia with a positional mid diastolic click. Examination of the extremities showed 3+ pitting edema up to the knees bilaterally. A chest x-ray film revealed left lower lobe atelectasis with pronounced left-sided pleural effusion and prominent pulmonary vasculature. An electrocardiogram showed sinus tachycardia with left atrial enlargement. The patient was admitted to the hospital with the diagnosis of new-onset congestive heart failure of unclear cause with possible left lower lobe pneumonia. Transthoracic echocardiography showed a huge left atrial multilobar mass blocking the mitral orifice; left ventricular function was normal. Transesophageal echocardiograms (Figure 1, Figure 2) confirmed these findings, demonstrating that the mass appeared to be attached to the posterior wall of the left atrium with possible extension of the mass into the left inferior pulmonary vein. The interatrial septum was not involved. Cardiac catheterization revealed normal coronary arteries and an increased pulmonary capillary wedge pressure of 37 mm Hg in the right pulmonary artery (wedge pressure was not measured on the left side), with pulmonary artery pressures of 67/33 mm Hg. In the levo-phase of both the left and the right pulmonary artery angiograms, a large left atrium with an intracavitary filling defect was evident, with only the inferomedial aspect of the left atrium filling with contrast. Extension into the pulmonary vein was not clearly evident. There was no evidence of vascular supply by either the aorta or the pulmonary artery irrigating this mass. A ventriculogram showed normal contractility with an ejection fraction of 60%, with evidence of an immobile posterior mitral valve leaflet and regurgitation in a very limited space in the left atrium.Figure 2Transesophageal echocardiogram showing prolapse of left atrial mass into the left ventricle in diastole. The mass completely obliterates the mitral orifice. a = large mass in the left atrium; b = right ventricle; c = right atrium; d = aortic valve in diastole.View Large Image Figure ViewerDownload (PPT) During hospitalization, the patient's condition deteriorated rapidly. He became hypotensive with a blood pressure of 70/40 mm Hg and required intubation to maintain adequate oxygenation. Aggressive fluid support, pressors, and positional changes to the Trendelenburg position were necessary for optimization of his hemodynamic variables. Because the tumor was causing left ventricular inflow obstruction and the patient's cardiorespiratory condition was life-threatening, emergent cardiac surgery was performed within 24 hours of admission to the hospital. At surgery, approximately 3 L of pleural fluid, found to be transudative, was removed. A pericardial flap approximately 10 cm × 10 cm was excised, and the patient underwent cardiopulmonary bypass. Autotransplantation of his heart was necessary to remove the extensive tumor. His entire heart, except the posterior atrial wall to which the tumor was attached, was removed and preserved. The tumor and the posterior aspect of the left atrial wall were removed and sent for pathologic study (Figure 3). Further examination of the resected heart showed that the tumor extended into the left inferior pulmonary vein. Removing the tumor completely from the left inferior pulmonary vein was difficult. The resected pericardium was used as the posterior left atrial wall, the heart was reimplanted, and the patient was successfully weaned off bypass. However, because the tumor extended into the left inferior pulmonary vein, a left lower lobectomy with removal of that pulmonary vein was performed. During this second surgery, his whole left lower lobe was noted to be infiltrated by tumor. The patient's condition improved substantially after the surgeries. However, metastases to both the brain and the liver were found on postoperative examinations. The mass, which weighed 70 g and was 8 × 6.5 × 4 cm, was irregular and nodular. One aspect was relatively smooth, glistening, and nodular. The opposite aspect had a more fragmented, irregular papillary appearance with many small papillary to nodular areas. In some foci, they were like clusters of small grapes, varying from 0.2 to 0.5 cm in diameter (Figure 3). The cut surface revealed a variegated appearance from pale tan to areas with hemorrhage and necrosis involving the central portion of the lesion. Pathologic study of both the left atrial mass and the lung tumor showed a malignant neoplasm with papillary areas and various morphologic patterns suggestive of a germ cell tumor (Figure 4). Inmunohistochemical studies revealed positive markers for keratins, vimentin, and CD56 and CD99, favoring the diagnosis of a biphasic blastoma that originated in the lung and extended into the left atrium. A pulmonary blastoma is a rare malignancy, representing less than 1% of all lung cancers.4Kliem V Bugge M Leimenstoll K Maschek H Pulmonary blastoma—a rare tumour.Clin Investig. 1992; 70: 927-931Crossref PubMed Scopus (19) Google Scholar This tumor mimics the embryonic elements of the lung in early fetal development. A pulmonary blastoma should not be confused with the pleuropulmonary blastoma of childhood, which is analogous to a Wilms tumor of the lung in which there is no recognizable neoplastic epithelium. The 2 types of pulmonary blastoma are biphasic and fetal, also known as well-differentiated fetal adenocarcinoma.5Muller-Hermelink HK Kaiserling E Pulmonary adenocarcinoma of fetal type: alternating differentiation argues in favour of a common endodermal stem cell.Virchows Arch A Pathol Anat Histopathol. 1986; 409: 195-210Crossref PubMed Scopus (33) Google Scholar, 6Kodama T Shimosato Y Watanabe S Koide T Naruke T Shimase J Six cases of well-differentiated adenocarcinoma simulating fetal lung tubules in pseudoglandular stage: comparison with pulmonary blastoma.Am J Surg Pathol. 1984; 8: 735-744Crossref PubMed Scopus (85) Google Scholar, 7Nakatani Y Dickersin GR Mark EJ Pulmonary endodermal tumor resembling fetal lung: a clinicopathologic study of five cases with immunohistochemical and ultrastructural characterization.Hum Pathol. 1990; 21: 1097-1107Abstract Full Text PDF PubMed Scopus (58) Google Scholar Biphasic pulmonary blastomas contain both neoplastic glandular tissue and either adult sarcomatous or embryonic mesenchymal tissue,8Hage E Electron microscopic identification of endocrine cells in the bronchial epithelium of human foetuses.Acta Pathol Microbiol Scand [A]. 1972; 80: 143-144PubMed Google Scholar, 9Hage E Endocrine cells in the bronchial mucosa of human foetuses.Acta Pathol Microbiol Scand [A]. 1972; 80: 225-234PubMed Google Scholar whereas a well-differentiated fetal adenocarcinoma contains solely malignant glands of embryonic appearance. Several stage-specific embryonic antigens have been observed in the neoplastic cells of pulmonary blastomas, supporting an embryonal nature.10Inoue H Kasai K Shinada J Yoshimura H Kameya T Pulmonary blastoma: comparison between its epithelial components and fetal bronchial epithelium.Acta Pathol Jpn. 1992; 42: 884-892PubMed Google Scholar, 11Yazawa T Ogata T Kamma H Shibagaki T Iijima T Horiguchi H Pulmonary blastoma with a topographic transition from blastic to more differentiated areas: an immunohistochemical assessment of its embryonic nature using stage-specific embryonic antigens.Virchows Arch A Pathol Anat Histopathol. 1991; 419: 513-518Crossref PubMed Scopus (10) Google Scholar However, because of the existence of composite cases showing features of pulmonary blastoma and carcinosarcoma and because of sporadic cases displaying aberrant types of differentiation in pulmonary blastomas, including melanocytic and yolk sac elements, origin from a pluripotential stem cell is currently favored by most investigators.12Berho M Moran CA Suster S Malignant mixed epithelial/mesenchymal neoplasms of the lung.Semin Diagn Pathol. 1995; 12: 123-139PubMed Google Scholar Biphasic blastomas occur at any age, with the mean age at diagnosis being 35 to 40 years.13Koss MN Hochholzer L O'Leary T Pulmonary blastomas.Cancer. 1991; 67: 2368-2381Crossref PubMed Scopus (264) Google Scholar In 80% of patients, there is a history of tobacco use, suggesting that the same agents that are thought to have a role in the pathogenesis of bronchogenic carcinomas may also be involved in the development of pulmonary blastomas.13Koss MN Hochholzer L O'Leary T Pulmonary blastomas.Cancer. 1991; 67: 2368-2381Crossref PubMed Scopus (264) Google Scholar Approximately 25% to 40% of patients are asymptomatic at presentation, with incidental diagnosis by chest radiography. Hemoptysis and cough are the most common symptoms in patients with tumors affecting the bronchi, whereas chest pain is common when the pleura is involved.13Koss MN Hochholzer L O'Leary T Pulmonary blastomas.Cancer. 1991; 67: 2368-2381Crossref PubMed Scopus (264) Google Scholar, 14Francis D Jacobsen M Pulmonary blastoma.Curr Top Pathol. 1983; 73: 265-294Crossref PubMed Scopus (113) Google Scholar, 15Dail DH Uncommon tumors.in: Dail DH Hammar SP Pulmonary Pathology. 2nd ed. Springer-Verlag, New York, NY1994: 1312-1317Crossref Google Scholar Pleural effusions occur occasionally. Radiography shows a well-demarcated peripheral lesion encapsulated by compressing or atelectatic lung tissue.16Thompson TT Roentgen manifestations of pulmonary blastoma.Chest. 1972; 62: 104-105Crossref PubMed Scopus (10) Google Scholar Some lesions tend to be lobulated and cavitated. The lesions are large, from 2.5 to 25 cm, and grow rapidly; frequently, hemorrhage and necrosis are noted on gross pathologic specimens.13Koss MN Hochholzer L O'Leary T Pulmonary blastomas.Cancer. 1991; 67: 2368-2381Crossref PubMed Scopus (264) Google Scholar, 14Francis D Jacobsen M Pulmonary blastoma.Curr Top Pathol. 1983; 73: 265-294Crossref PubMed Scopus (113) Google Scholar, 15Dail DH Uncommon tumors.in: Dail DH Hammar SP Pulmonary Pathology. 2nd ed. Springer-Verlag, New York, NY1994: 1312-1317Crossref Google Scholar The prognosis is worse with the biphasic blastoma than with the fetal type because of the high incidence of metastasis in the former.13Koss MN Hochholzer L O'Leary T Pulmonary blastomas.Cancer. 1991; 67: 2368-2381Crossref PubMed Scopus (264) Google Scholar Overall, survival is 25% at 1 year and 16% at 5 years. 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If metastases are present, survival is unlikely despite therapy. An extensive literature search disclosed no previous report of a pulmonary blastoma extending into the heart. The unique aspect of our case is the presentation of this tumor as a cardiac mass in the left atrium, in some ways resembling the typical presentation of an obstructive left atrial mass (eg, myxoma), in a patient with severe hemodynamic compromise and no symptoms suggestive of a lung tumor. Whether this tumor originated in the lung and spread to the left atrium by direct extension through the pulmonary veins or whether it represents a primary carcinosarcoma of the heart as described by Chen25Chen KT Carcinosarcoma of the heart.J Surg Oncol. 1984; 27: 48-50Crossref PubMed Scopus (3) Google Scholar is debatable. However, based on our review of the literature and discussion with various pathologists, the latter seems unlikely.