Ann Thorac Surg 2008;86:661-663. doi:10.1016/j.athoracsur.2008.02.042
© 2008 The Society of Thoracic Surgeons
Case Reports
Respiratory Failure Caused by Giant Thymolipoma
Sami Ceran, MDa,
Baykal Tulek, MDb,*,
Guven Sunam, MDa,
Mecit Suerdem, MDb
a Department of Thoracic Surgery, Meram Faculty of Medicine, Selcuk University, Konya, Turkey
b Department of Pulmonary Medicine, Meram Faculty of Medicine, Selcuk University, Konya, Turkey
Accepted for publication February 14, 2008.
* Address correspondence to Dr Tulek, Selcuk Universitesy, Meram Tip Fakultesi, Gogus Hastaliklari AD, Konya, 42080, Turkey (Email: baykaltulek{at}yahoo.com).
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Abstract
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The authors present the case of a 31-year-old woman with a massive anterior mediastinal tumor who presented with respiratory failure. A thoracic computed tomographic scan suggested a mediastinal lipomatous mass, and an operation was performed. Resection of the tumor resulted in immediate improvement in the patient's pulmonary status, and the histopathologic examination revealed thymolipoma. Because thymolipoma can attain enormous dimensions and compress adjacent structures, it should be immediately resected.
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Introduction
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Thymolipoma is a rare benign tumor of the anterior mediastinum. These tumors account for 2% to 9% of thymus tumors [1]. The tumor grows slowly and can become large before symptoms occur. Most thymolipomas are diagnosed incidentally after routine radiographic imaging [2]. We describe an adult in which a thymolipoma caused respiratory failure.
A 31-year-old woman was admitted to our clinic with progressive dyspnea of 3 years. She mentioned that even though she received several brochodilator and diuretic therapies, her dyspnea was not relieved. She had no smoke or occupational exposure history. On physical examination, lung sounds were absent in both anterior lung fields. A chest x-ray film showed an enlarged mediastinum with homogenous opacities overlying both sides of the heart (Fig 1). A pulmonary function test revealed severe restriction (forced vital capacity, 28%) and arterial blood gases analysis showed severe hypoxemia at rest (PaO2, 48 mm Hg). An echocardiogram showed normal left and right ventricular function. A thoracic computed tomographic scan revealed a huge mass that occupied the entire anterior mediastinum with posterior and caudal displacement of both lungs. There was no sign of invasion of neighboring structures. The mass consisted of fatty tissue elements interspersed with soft tissue and no calcification was observed (Fig 2). A magnetic resonance scan of the chest confirmed the fatty nature of the mass (Fig 3).
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Fig 1. The chest roentgenogram demonstrating an enlarged mediastinum with homogenous opacities overlying both sides of the heart.
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Fig 2. Thorax computed tomographic image of the mass occupying the entire anterior mediastinum with posterior and caudal displacement of both lungs.
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Because of the respiratory compromise and the benign radiographic appearance of the tumor, a biopsy was not obtained, and the patient underwent surgery. A large lipomatous mass was found occupying the entire anterior mediastinum draped over the pericardium, extending to both pleural spaces. There was no invasion of contiguous structures by the tumor, and it was easily dissected off the surrounding organs. The mass was resected through a median sternotomy. The mass weighed 5,500 g. A pathologic examination of the resected block revealed diagnosis of thymolipoma.
Resection of the tumor resulted in immediate improvement in the patient's pulmonary status, and she was discharged in good health.
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Comment
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Thymolipoma is an uncommon benign tumor of the anterior mediastinum. This tumor accounts for only a small percentage (2% to 9%) of thymic tumors [1]. The highest incidence occurs in young adults with a mean age of 33 years [2]. The tumors are usually large, most weighing more than 500 g, with 25% weighing more than 2,000 g. Rarely they can reach a huge size. The largest of these tumors that have been reported in the literature weighed 6,000 g [3]. We believe that our case is the second largest one in the literature.
Most patients are asymptomatic, and the tumors are identified incidentally during a diagnostic workup for other medical problems. Approximately half of the patients with this tumor experience symptoms, such as dyspnea, chest pain, cyanosis, tachypnea, and chronic nonspecific chest symptoms. Thymolipoma may be rarely associated with myastenia gravis [4].
The radiologic features of thymolipoma can mimic several conditions including cardiomegaly, pericardial efusion, and pericardial tumors [5]. On computed tomographic scan, the tumor appears as linear strands and whorls of soft tissue intermixed with fat or as rounded islands of soft tissue surrounded by fat. The adipose tissue of the tumor appears isointense in T1-weighted magnetic resonance images, and the adipose tissues appear suppressed in T2-weighted sequences, whereas the remains of the thymic tissue are enhanced [4].
Thymolipomas are characterized by mesodermal and endodermal elements. Some thymolipomas show predominantly mature adipose tissue with only occasional remnants of thymic tissue. However, other thymolipomas have been reported to have a greater proportion of thymic tissue. The pathogenesis of thymolipoma is still uncertain. Replacement of diffuse thymic hyperplasia by adipose tissue seems to be the most widely accepted explanation [4]. The only curative treatment is surgical resection of the tumor. Because diagnosis can be established by imaging, a biopsy might not be needed to confirm histology of the tumor. The encapsulated and lobular nature of thymolipomas and lack of invasion into adjacent structures allow for a relatively uncomplicated surgical excision of the tumor [1].
In conclusion, our case represents an atypical clinical presentation of giant thymolipoma with respiratory failure. The patient had longstanding respiratory complaints because of thymolipoma. The compression of the lungs by the thymolipoma resulted in reduced lung volume. The reduced lung volume caused chronic respiratory symptoms and a restrictive lung pattern unresponsive to medical therapy.
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References
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- Halkos ME, Symbas JD, Symbas PN. Acute respiratory distress caused by massive thymolipoma South Med J 2004;97:1123-1125.[Medline]
- Moran CA, Rosado-de-Christenson M, Suster S. Thymolipoma: clinicopathologic review of 33 cases Mod Pathol 1995;8:741-744.[Medline]
- Dunn BH, Frkovich G. Lipomas of the thymus gland with an illustrative case report Am J Pathol 1956;32:41-51.[Medline]
- Rosado-de-Christenson ML, Pugatch RD, Moran CA, Galobardes J. Thymolipoma: analysis of 27 cases Radiology 1994;193:121-126.[Abstract/Free Full Text]
- Gamanagatti S, Sharma R, Hatimota P, Guleria R, Arvind S. Giant thymolipoma AJR Am J Roentgenol 2005;185:283-284.[Free Full Text]
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Abstract
Introduction
