Ann Thorac Surg 2007;83:2203-2205
© 2007 The Society of Thoracic Surgeons
Case Reports
Lipoma of the Diaphragm: A Rare Presentation
Serdar 
en, MDa,*,
Berent Di
cigil, MDb,
smail Badak, MDb,
U
ur Gürcün, MDb
a Department of General Thoracic Surgery, Adnan Menderes University, Faculty of Medicine, Aydin, Turkey
b Department of Cardiovascular Surgery, Adnan Menderes University, Faculty of Medicine, Aydin, Turkey
Accepted for publication January 22, 2007.
* Address correspondence to Dr en, General Thoracic Surgery Department, Adnan Menderes University, Faculty of Medicine, Aydin, 09100, Turkey (Email: drserdarsen{at}yahoo.com).
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Abstract
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Lipoma of the diaphragm is an extremely rare entity. A 67-year-old asymptomatic man who had a tumor located in the posterior region of the left hemi-diaphragm is presented. The tumor was removed through a left mini-thoracotomy. The diaphragm was reconstructed primarily by using nonabsorbable suture material. The final pathologic examination revealed a mature lipoma. The patient remains without evidence of recurrence 60 months after the operation.
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Introduction
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Primary tumors of the diaphragm are rarely seen, especially benign ones, which are very uncommon [1]. Diaphragmatic lipoma is a very rare entity and it is located predominantly on the left side (ratio, 2 to 1) and posterolateral area of the diaphragm [2], although lipoma is the most common benign tumor of the diaphragm [1]. Benign tumors, including lipomas and cystic masses (such as bronchogenic, mesothelial, and teratoid cysts) are most frequently reported diaphragmatic tumors. The diaphragm is commonly involved with malignant pleural or peritoneal disease [2]. Most malignant tumors are sarcomas of fibrous or muscular origin [1]. Surgical exploration is recommended because the possibility of liposarcoma can not be excluded [3].
A 67-year-old man was admitted for back pain. His physical examination was normal other than moderate high blood pressure. Auscultatory findings of the chest were normal. No abnormality was found in his complete blood count, biochemical studies, and tumor markers. Erytrocyte sedimentation rate was 15 mm/1 h. Arterial blood gases on air were PaO2 = 65.5 mm Hg, PaCO2 = 47 mm Hg, pH = 7.417, base excess = 6.5, bicarbonates = 30.6, and saturation = 95%. A spirogram showed almost normal data with forced vital capacity = 2.83 L (84.7%), forced expiratory volume in 1 second = 2.06 L (63.1%), and forced expiratory volume in 1 second/forced vital capacity = 72.7%.
A chest roentgenogram revealed a 5 x 6 cm mass obscuring the posterior contour of the diaphragm in the lateral view (Fig 1). The appearance of the mass on computed tomographic scan (CT) examination was 5 x 5 cm in size, fat in density (–90 Hounsfield unit), which was located in the base of the left lung adjacent to the pleura (Fig 2).
The patient underwent a left posterior mini-thoracotomy. In surgery the mass was found in the posterior localization of the diaphragm, and it was totally free of lung tissue. It was yellowish pink in color, covered by diaphragmatic pleura, and it originated from muscle tissue of the diaphragm (Fig 3). The mass was resected in total, and the remaining defect on the pleural surface of the diaphragm was repaired by direct suturing with 2-0 nonabsorbable suture material. Light microscopy showed a lipoma consisting of mature adipose tissue, and no evidence of malignancy existed. The patient made an uneventful recovery and was discharged home 6 days postoperatively. To date (5 years after the operation), the patient remains in good condition without evidence of recurrence on diagnostic imaging.
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Comment
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Primary tumors of the diaphragm are rare and commonly present in the fourth and fifth decades of life. There have been less than 200 cases described in the English literature between 1868 and 2005 [4].
Grancher described a primary diaphragmatic tumor, which was a benign fibroma in 1868 [2]. Clark described a diaphragmatic lipoma in 1886 [4]. In a 71-patient series with primary diaphragmatic neoplasms, only 9 patients had lipomas [3]. Lipomas, mesothelial cysts, neurofibroma, and angiofibroma are common benign tumors [3, 5, 6], and lipomas make up 35% of them. Furthermore, lipomas are rarely seen in the thoracic cavity [6, 7]. These two rarely seen features, being primary diaphragmatic lipoma grown into the thoracic cavity are present in the patient reported in this article. On the other hand, primary malignant neoplastic lesions are mostly mesenchymal origins of the diaphragm. Rhabdomyosarcoma is the most common malignant tumor of the diaphragm [4]. The diaphragm is commonly involved with malignant pleural or peritoneal disease [3].
Tumors of the diaphragm are not associated with any characteristic symptom [7]. The presentation of the patient with a diaphragmatic tumor is variable depending on age at presentation, size of mass, involvement of adjacent organs, or metastatic disease, and tumor histology. "Chest-associated" symptoms are more common than "abdomen-associated" symptoms at presentation. Clinical presentation was reported by authors to be a combination of chest, shoulder, and back pain, shortness of breath, cough, hemoptysis and respiratory failure, and rupture of the diaphragm [3–6]. However, most diaphragmatic lipomas are incidentally found [3, 5, 6]. There was slight elevation in the preoperative blood PCO2 level of the patient presented in this case report, without any shortness of breath. However we have no clear evidence whether CO2 retention has any relation with reduced diaphragmatic function if there is any in the present patient.
Radiologic evaluation is extremely important that 0 and –100 Hounsfield unit are defined as CT number for water and air, respectively. Fatty tissue corresponds –80 to –135 Hounsfield unit. Negative CT numbers are observed only in air and fatty tissue [6, 8]. Due to the high specificity of CT scan in identifying homogenous fat-containing structure, the diagnosis of lipoma was established with certainity [6]. Diaphragmatic lipoma is located predominantly on the left side (ratio, 2 to 1) and posterolateral area of the diaphragm [2]. Lobulations, localized eventration slip or hypertrophic diaphragmatic crus may simulate tumors of the diaphragm, and this should be kept in mind during evaluation [1, 6, 8]. In this regard, diaphragmatic hernia or eventration containing omentum should be taken into consideration as a possibility in differential diagnosis. Occasionally the left kidney is located in a high position and locally elevates the diaphragm, mimicking a neoplasm [6].
The management of asymptomatic diagnostic lipomas has not been established. Some authors recommend a radiologic follow-up of asymptomatic noninfiltrating diaphragmatic lipomas, whereas others insist on surgery because of the risk of developing a diaphragmatic liposarcoma [2, 3, 5]. Although malignant changes in a lipoma are exceedingly rare, some of these are pleomorphic lipomas and others are well-differentiated liposarcomas in which the malignant characteristics were missing when the tumor was first examined [3, 5]. Differentiation between diaphragmatic lipoma and a malignant tumor (such as liposarcomas) often relies on the assumption that malignancy would often be associated with a pleural effusion [3]. However it has been suggested that histologic examination of a completely resected specimen is a much safer way to secure final diagnosis. Therefore we have decided that surgical resection rather than conservative management by close observation alone is a safer way of treatment for the outcome of the patient presented in this report [3].
To ensure complete surgical resection a diaphragmatic tumor, a portion of the hemidiaphragm usually has to be sacrificed, which may necessitate repair with a muscular flap or exogenous material such as polytetrafluoroethylene (or Gore-Tex [W.L. Gore & Assoc, Flagstaff, AZ]) [4]. In surgery we were able to reconstruct the diaphragm by simple suturing without using a patch material.
In conclusion, a patient is presented with lipoma, which originated in the left hemidiaphragm, detected as an abnormal pulmonary shadow on chest roentgenogram. We recommend surgical exploration because the possibility of liposarcoma can not be excluded. Treatment of the patient was surgical excision of the tumor and primary closure of the defect on the diaphragm. To date, 5 years after the operation, our patient has been in good condition, without evidence of recurrence on diagnostic imaging.
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References
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- Weksler B, Ginsberg RJ. Tumors of the diaphragm Chest Surg Clin N Am 1998;8:441-447.[Medline]
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- Cada M, Gerstle JT, Traubici J, Ngan BY, Capra ML. Approach to diagnosis and treatment of pediatric primary tumors of the diaphragm J Pediatr Surg 2006;41:1722-1726.[Medline]
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- Shimizu J, Hashimoto T, Imai T, Kawahara E. Primary lipoma of the diaphragm Respiration 1996;63:397-399.[Medline]
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Ann. Thorac. Surg.,
July 1, 2008;
86(1):
261 - 265.
[Abstract]
[Full Text]
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Abstract
Introduction
