Case Study

Thoracoscopic enucleation for intrapulmonary lipoma: Case report

Asian Cardiovascular & Thoracic Annals 2015, Vol. 23(3) 338–340 ß The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492314531586 aan.sagepub.com

Yusuke Takahashi, Toshiyuki Shima, Masahiko Harada and Hirotoshi Horio

Abstract A 67-year-old woman with a history of uterine body cancer was admitted because of a nodular shadow in the right lower lobe on chest computed tomography. We planned thoracoscopic resection for diagnosis. Thoracoscopically, the tumor was seen through the visceral pleura as a round yellow nodule close to the inferior pulmonary vein, and it was soft on palpation with surgical forceps, which was consistent with intrapulmonary lipoma. We therefore performed thoracoscopic enucleation. Histological examination confirmed an intrapulmonary lipoma. We report the first case of intrapulmonary lipoma which was enucleated thoracoscopically.

Keywords Lipoma, Lung neoplasms, Thoracoscopy

Introduction Although lipoma is one of the most common benign soft tissue neoplasms, intrathoracic lipoma is rare. Most intrathoracic lipomas arise from a proximal bronchus; intrapulmonary lipomas arising in the lung parenchyma are extremely rare.1 To our knowledge, there are only 12 previous cases in the literature.2–7 We describe a case of intrapulmonary lipoma which was enucleated thoracoscopically.

Case report A 67-year-old asymptomatic woman who had never smoked was referred to us because of a nodular shadow in the right lower lobe on chest computed tomography (CT). She had undergone a hysterectomy for uterine body cancer 7 years earlier, and no abnormal shadows were detected on chest CT one year earlier. CT demonstrated a well-defined round low-density (approximately 100 Hounsfield units) nodule without calcification, which was 8 mm in size, located in the right segment 7 close to the visceral pleura (Figure 1). Positron-emission CT revealed neither significant accumulation in the nodular lesion and nor lesions elsewhere. Physical and laboratory examinations including serum tumor markers showed no significant

abnormalities. It was difficult to obtain adequate histological samples via an endobronchial or percutaneous approach because the lesion was located adjacent to the inferior pulmonary vein (IPV). Therefore, we planned partial resection of the right lower lobe or basal segmentectomy employing a thoracoscopic approach. Intraoperatively, the tumor was visible through the visceral pleura as a pale yellow round nodule close to the IPV (Figure 2). Careful palpation with surgical forceps revealed the nodule to be very soft. These observations suggested the lesion to be an intrapulmonary lipoma. We thus performed thoracoscopic enucleation using electrical cautery to preserve the IPV because we confirmed the tumor to be located within 1 cm of the IPV after dissection of the pulmonary ligament. Intraoperative frozen sections demonstrated no cellular component and the stamped cytology of the cut-surface of the specimen revealed a small number of adipocytes Department of General Thoracic Surgery, Tokyo Metropolitan Cancer and Infectious Disease Center, Komagome Hospital, Tokyo, Japan Corresponding author: Yusuke Takahashi, Department of General Thoracic Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan. Email: [email protected]

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Figure 1. High-resolution chest computed tomography (lung window) revealed a well-defined round solid nodule, 8 mm in size, located in the right segment 7 (arrowhead). The fat containing nodule was demonstrated on the mediastinal window (arrowhead).

Figure 2. Intraoperative thoracoscopic findings indicated the lesion to be a pale yellow rounded nodule (arrow).

and a few neutrophils but no malignant cells. These findings were consistent with lipoma. We applied a tissue sealant sheet (TachoSil; CSL Behring, King of Prussia, PA, USA) to the surgical margin to prevent postoperative air leakage because the defect in the visceral pleura was narrow. The patient’s postoperative course was uneventful. Macroscopically, the tumor was a well-demarcated yellowish nodule, 8 mm in size (Figure 3). The hematoxylin and eosin stained section revealed mature adipocytes without atypia in the nodular area, which was bordered by fibers extending into the surrounding normal pulmonary parenchyma. The nodule was diagnosed as an intrapulmonary lipoma (parenchymal type) with a negative surgical margin (Figure 3). The patient continues to return for follow-up visits and she has remained alive with no evidence of recurrence for 15 months since the surgery.

Figure 3. Lower magnification of hematoxylin and eosin stained sections revealed the fat-containing nodule to be surrounded by normal lung parenchyma. Inset: macroscopic cut surface revealed the yellow round nodule with a smooth border.

Discussion On rare occasions, lipomas can occur in the viscera,1 as in our patient with an intrapulmonary lipoma. The prevalence of bronchial lipoma is only 0.1% among all pulmonary tumors,8 and occurrence in the peripheral pulmonary parenchyma is even less frequent. The features of intrapulmonary lipoma are not well established. Most intrapulmonary lipoma cases are asymptomatic because the mass is located in the peripheral lung, with the majority being found incidentally on routine radiographs. Although intrapulmonary lipoma is benign, it can be difficult to distinguish clinically from malignant lesions. Thus CT may play a role in diagnosis whenever a defined homogenous mass with fat density (approximately 100 Hounsfield units) is detected.9 In the current case, the findings of high-resolution CT, which revealed a homogenous round fat-containing nodule, consistent

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with lipoma. However, when the lesion is small, it is potentially difficult to distinguish an intrapulmonary lipoma from many other benign intrapulmonary fatcontaining nodular lesions, such as lipomatous or chondromatous hamartoma, angiolipoma, lipoblastoma, or teratoma.9 The false-negative rate of subcentimeter pulmonary nodules is reported to be >19%.10 Therefore, the possibility of a metastatic tumor from uterine body cancer or a carcinoid tumor should be considered. Because the tumor in our patient was newly detected and we considered that it might have the potential to grow larger and become impossible to resect without sacrificing the right IPV, we decided to proceed with resection. This is the first report describing the diagnosis of an intrapulmonary lipoma based on intraoperative thoracoscopic findings, although several authors have reported radiographic diagnosis of intrapulmonary lipomas.4,7,11 The distinctive appearance consistent with that of lipomas is commonly seen. In this case, preoperative CT and intraoperative thoracoscopic findings were particularly important for diagnosis of intrapulmonary lipoma; accurate diagnosis allows the optimal surgical procedure, such as enucleation or wedge resection of the lung, to be selected. This case highlights the importance of carefully examining preoperative radiographic images and intraoperative findings including endoscopic visualization and palpation of pulmonary nodules, without a definitive preoperative diagnosis. Funding This research received no specific grant from any funding agency in the public, commerical, or not-for-profit sectors.

References 1. Enzinger FM and Weiss SW. Soft Tissue Tumors, 4th ed. Philadelphia: Mosby Publishing, 2001, pp. 571–581. 2. Kim NR, Kim HJ, Kim JK and Han J. Intrapulmonary lipomas: report of four cases. Histopathology 2003; 42: 305–306. 3. Civi K, Ciftc¸i E, Gu¨rlek Olgun E, Erginel S, Ozkan R and Metintas¸ M. Peripheral intrapulmonary lipoma: a case report and review of the literature. Tuberk Toraks 2006; 54: 374–377. 4. Wood J and Henderson RG. Peripheral intrapulmonary lipoma: a rare lung neoplasm. Br J Radiol 2004; 77: 60–62. 5. Erkilic¸ S, Koc¸er NE and Tunc¸ozgu¨r B. Peripheral intrapulmonary lipoma: a case report. Acta Chir Belg 2007; 107: 700–702. 6. Vassallo M, Rana Z and Allen S. A large transmural thoracic lipoma easily mistaken for pulmonary malignancy. Br J Clin Pract 1996; 50: 285–286. 7. Guermazi A, El Khoury M, Perret F, et al. Unusual presentations of thoracic tumors: case 3. Parenchymal lipoma of the lung. J Clin Oncol 2001; 19: 3784–3786. 8. Moran AM, Jian B, Min H, Pechet T and Fogt F. Peripheral intrapulmonary lipoma in a 26-year-old woman - a case report. Pol J Pathol 2011; 62: 113–115. 9. Gaerte SC, Meyer CA, Winer-Muram HT, Tarver RD and Conces DJ Jr. Fat-containing lesions of the chest. Radiographics 2002; 22: S61–S78. 10. JH O, Yoo IeR, Kim SH, Sohn HS and Chung SK. Clinical significance of small pulmonary nodules with little or no 18F-FDG uptake on PET/CT images of patients with nonthoracic malignancies. J Nucl Med 2007; 48: 15–21. 11. Doulias T, Gosney J and Elsayed H. An intra-parenchymal pulmonary lipoma with a high activity on positron emission tomography scan. Interact Cardiovasc Thorac Surg 2011; 12: 843–844.

Conflict of interest statement None declared.

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Thoracoscopic enucleation for intrapulmonary lipoma: case report.

A 67-year-old woman with a history of uterine body cancer was admitted because of a nodular shadow in the right lower lobe on chest computed tomograph...
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