Indian Journal of Pathology and Microbiology

CASE REPORT
Year
: 2012  |  Volume : 55  |  Issue : 4  |  Page : 513--515

Malignant pleural mesothelioma forming a huge mediastinal mass and causing atrial fibrillation


Hiroko Kuwabara1, Hiroshi Tsuji2, Yuki Inada3, Yuro Shibayama1,  
1 Department of Pathology, Osaka Medical College, Osaka, Japan
2 Department of Internal Medicine, Osaka Medical College, Osaka, Japan
3 Department of Radiology, Osaka Medical College, Osaka, Japan

Correspondence Address:
Hiroko Kuwabara
Department of Pathology, Osaka Medical College, 2-7 Takatsuki, Osaka 569-8686
Japan

Abstract

A patient with malignant pleural mesothelioma was admitted with atrial fibrillation. Chest computed tomography showed a huge mediastinal tumor adjacent to the heart. Autopsy revealed a 12 × 9.5 -cm mediastinal mass involving the right lung, which distorted and stretched the myocardial sleeve surrounding the right inferior pulmonary vein. This case demonstrates that advanced malignant pleural mesothelioma can cause atrial fibrillation, possibly by stimulating myocardium around a pulmonary vein.



How to cite this article:
Kuwabara H, Tsuji H, Inada Y, Shibayama Y. Malignant pleural mesothelioma forming a huge mediastinal mass and causing atrial fibrillation.Indian J Pathol Microbiol 2012;55:513-515


How to cite this URL:
Kuwabara H, Tsuji H, Inada Y, Shibayama Y. Malignant pleural mesothelioma forming a huge mediastinal mass and causing atrial fibrillation. Indian J Pathol Microbiol [serial online] 2012 [cited 2020 Oct 24 ];55:513-515
Available from: https://www.ijpmonline.org/text.asp?2012/55/4/513/107794


Full Text

 Introduction



Malignant mesothelioma typically develops diffusely along the serosal membrane. In the advanced stage, mesothelioma may form a mediastinal mass, with compression of the adjacent organs causing many complications. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, and the majority of episodes are triggered by atrial ectopic beats originating from the muscle fibers extending from the left atrium along the pulmonary veins. [1] This has led to the development of radiofrequency catheter ablation therapy of the pulmonary veins, which is effective in drug-resistant cases of AF. Here, we present a patient with advanced pleural mesothelioma, who was admitted with AF. Autopsy showed a large mediastinal tumor compressing and stretching the muscle fibers around the right inferior pulmonary vein.

 Case Report



A 66-year-old man, with no history of occupational exposure to asbestos, presented to our hospital for the treatment of a right pleural effusion and spontaneous pneumothorax. Pleural fluid cytology and chest computed tomography (CT) did not show any evidence of malignancy, and he was discharged with regular observation. Follow-up chest CT revealed a progressive right pleural thickening, and a CT-guided right pleural biopsy was performed at age 69 years. Histological examination of the biopsy specimen showed epithelioid tumor cells proliferating in tubular and sheet-like patterns with a fibrous stroma [Figure 1]a, which stained positive for calretinin [Figure 1]b, D2-40 [Figure 1]c, epithelial membrane antigen, cytokeratin 5/6 and mesothelial cell (HBME-1), and negative for carcinoembryonic antigen and thyroid transcription factor-1. He was diagnosed with pleural mesothelioma, and was treated with Specific Substance Maruyama at his request for 14 months. At age of 70 years, he was admitted to our hospital complaining of chest pain, dyspnea, abdominal fullness and leg edema. His blood pressure was 90/60 mmHg, and electrocardiography showed AF with a heart rate of 170 beats per minute. Chest CT showed a huge mass involving the mediastinum and the right lung, adjacent to the heart [Figure 2]. Abdominal CT showed ascites and multiple nodules, suggesting metastatic mesothelioma. He was treated with oral pirmenol for AF, and reverted to sinus rhythm after 1 week. His ascites was drained, and intravenous parenteral nutrition was administered. However, his general condition deteriorated, and he died on the 29 th day after admission.{Figure 1}{Figure 2}

An autopsy was performed. The volumes of left pleural fluid and ascites were 1200 mL and 2300 mL, respectively. There was marked right pleural thickening due to tumor, which extended into the thoracic wall. There was also a tumor mass measuring 12 x 9.5 cm involving the mediastinum, pericardium, and right lung, and adjacent to the right atrium and the myocardial sleeve surrounding the right inferior pulmonary vein [Figure 3]a. The tumor compressed the inferior vena cava, which appeared to be the cause of the leg edema. Metastatic tumor was detected in the right diaphragm, left lung, peritoneum, omentum, mesentery, psoas major muscle, right adrenal gland, lymph nodes of the right lung hilum, and abdominal para-aortic lymph nodes. There were no bone metastases, and no thyroid abnormalities. Histological examination showed tumor cells proliferating in tubular, papillary, microcystic, and sheet-like patterns. In addition to these epithelioid cells, a spindle-shaped sarcomatoid component was seen. The sharp circumscribed tumor of the mediastinum distorted and stretched the myocardium surrounding the right inferior pulmonary vein [Figure 3]b and c. A sarcomatoid component predominated in the abdominal tumor. Immunohistochemical staining of the epithelioid tumor cells showed the same results as the biopsied pleural specimens, and spindle tumor cells stained positive only for calretinin. A final diagnosis of biphasic pleural mesothelioma was made.{Figure 3}

 Discussion



Malignant mesothelioma typically presents as diffuse pleural thickening, but may also present as a bulky mass in the advanced stage. Compression of adjacent organs by an enlarging mediastinal tumor can cause many complications. Narrowing or obstruction of the superior vena cava, inferior vena cava, trachea, and esophagus may cause superior vena cava syndrome, leg edema, dyspnea, and dysphagia, respectively. AF can occur in patients with mediastinal tumors. [2],[3],[4],[5],[6],[7],[8],[9] In these patients, the tumor compressed the left atrium and the myocardium surrounding a pulmonary vein, and the myocardial fibers were mechanically stretched. In the present case, structural heart disease, thyroid abnormality, and hypertension were absent, and a huge mediastinal tumor compressing the myocardium around the right inferior pulmonary vein seemed to be the cause of the AF. To the author's knowledge, this is the first reported case of AF associated with a malignant mesothelioma which distorted and stretched the myocardium around a pulmonary vein. Previously reported mediastinal tumors inducing AF include bronchogenic cyst, mature teratoma, lipoma, and esophageal cancer, [2],[3],[4],[5],[6],[7],[8],[9] and most were benign noninfiltrating tumors with a well-circumscribed margin, which caused stretching of the myocardial fibers. In our case, the mediastinal tumor adjacent to the heart and the right inferior pulmonary vein had a relatively well-circumscribed margin.

AF due to a mediastinal tumor can be cured by surgical excision of the tumor. [5],[6],[7],[8] Although the treatment of advanced mesothelioma is difficult, chemotherapy using pemetrexed and cisplatin, antibody-based therapies targeting epidermal growth factor receptor, and immunotherapy have been attempted recently. [10] Advanced mesothelioma can cause AF, and the reduction in the tumor size using such therapies may prevent AF. It is important to diagnose mesothelioma at an early stage.

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