Ann Thorac Surg 2007;84:221-224
© 2007 The Society of Thoracic Surgeons
Original Articles: General Thoracic
Treatment of Inflammatory Myofibroblastic Tumor of the Chest: The Extent of Resection
Hyun Joo Lee, MDa,
Jin Shun Kim, MDa,
Yong Soo Choi, MDa,
Kwhanmien Kim, MD, PhDa,
Young Mog Shim, MD, PhDa,
Joungho Han, MD, PhDb,
Jhingook Kim, MD, PhDa,*
a Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
b Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
Accepted for publication March 13, 2007.
* Address correspondence to Dr Kim, 50 Ilwon-Dong, Kangnam-Ku, Seoul, 135-710, Republic of Korea (Email: jkim{at}smc.samsung.co.kr).
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Abstract
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Background: Owing to the rarity of inflammatory myofibroblastic tumor, its pathology and clinical course are poorly understood.
Methods: We performed a retrospective chart review of patients diagnosed with inflammatory myofibroblastic tumor in the chest who underwent surgical resection.
Results: From 1995 to 2006, 15 patients (10 males and 5 females) underwent surgical procedures owing to inflammatory myofibroblastic tumors. The mean age of these patients was 31.3 years (range, 7 months to 61 years). Among them, 13 patients (86.7%) presented with respiratory symptoms such as cough, dyspnea, and hemoptysis. Seven patients presented with the tumor located in the lung parenchyma, 4 in the trachea, 2 in the main bronchus, 1 in the segmental bronchus, and 1 in the chest wall. The diagnosis was confirmed before surgery for only 1 patient (6.3%). The types of operations performed included lobectomies for 4 patients, wedge resections using video-assisted thoracic surgery for 4 patients, tracheal/bronchial resections with end-to-end anastomoses for 6 patients, and chest wall resection for 1 patient. Only 2 patients received adjuvant radiation therapy. We followed up with all patients postoperatively for a mean of 33.3 months (range, 1.2 months to 8.4 years). Fourteen patients were free of local recurrence or distant metastasis during the follow-up period.
Conclusions: Inflammatory myofibroblastic tumor usually requires surgical resection for both proper diagnosis and adequate treatment. Complete resection and achieving negative margins leads to excellent outcome.
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Introduction
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Inflammatory myofibroblastic tumor (IMBT) is a benign tumor first described in the lung by Brunn and associates [1]. Although IMBT is a rare disease, the most common sites are the lung and the eye orbit [2]. Inflammatory myofibroblastic tumor has been called plasma cell granuloma, xanthogranuloma, fibrous histiocytoma, or inflammatory pseudotumor, but inflammatory pseudotumor is the most well-known designation [2, 3] because the tumor is histopathologically composed of myofibroblasts and inflammatory cells such as histocytes, lymphocytes, and plasma cells [4]. However, IMBT is the most suitable terminology because inflammatory pseudotumor can encompass postinflammatory nodules [5]. Inflammatory myofibroblastic tumor in the lung is usually discovered as a solitary mass in the lung periphery, but in some cases is detected as an endobronchial mass along with respiratory symptoms. In this study, we reviewed our clinical experience to evaluate the diagnosis and treatment strategies for IMBT according to the subtypes.
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Patients and Methods
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The Samsung Medical Center Institutional Review Board approved this retrospective study with the use of a database from the Department of Thoracic Surgery (IRB No. 2006-12-023), and waived the need for patient consent. Between 1994 and 2006, 12,355 general thoracic procedures were performed at Samsung Medical Center, and 15 patients (0.12%) underwent surgery owing to IMBT. Medical records were reviewed for sex, age, presenting symptoms, location and size of the lesions, methods of treatment, and recurrence during routine follow-up. Chest computed tomography (CT) scans were performed preoperatively for all patients, and two radiologists independently reviewed the scans. In 12 of the 15 patients, helical CTs (HiSpeed Advantage; General Electric Medical Systems, Milwaukee, Wisconsin) with or without contrast were performed at our institution. The other 3 patients underwent CT scans at other centers using a Somatom Plus 40 scanner (Siemens, Forscheim, Germany). Bronchoscopy was also performed for preoperative evaluation, except for 1 patient who was too young for the procedure. The operations were performed by 3 surgeons at our center. An experienced pathologist re-reviewed all specimen slides and confirmed IMBT in each [6]. After surgery, all patients were regularly followed up with every 3 months at the outpatient clinic and underwent CT scans or bronchoscopic examinations once per year.
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Results
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Fifteen patients, 10 men and 5 women, underwent surgery for IMBT. The mean age was 31.3 ± 18.1 years (range, 7 months to 61 years). Thirteen patients (86.7%) were symptomatic and their presenting symptoms included cough (20.0%), dyspnea (26.7%), hemoptysis (20.0%), chest pain or discomfort (13.3%), and a palpable chest wall mass (6.7%). The other 2 patients (13.3%) were asymptomatic and their lesions were noticed on routine examinations.
On preoperative chest CT scans, the lesions manifested as a solitary mass with discrete margins in 14 of 15 patients regardless of location (Table 1). Only 1 patient had 3 bilateral parenchymal mass lesions. The masses usually had homogenous attenuation, but atypical shadows were shown in 2 cases due to necrosis within the tumor. Calcifications in the mass were found in 2 cases, 1 of which revealed tumor blood vessels supplied from the abdominal aorta. The mean mass size was 2.7 ± 2.0 cm in diameter (range, 1.2 to 9.0 cm).
Tumors were located within the airway in 7 patients (4 tracheal, 2 main bronchial and 1 in the segmental bronchus). Seven patients had tumors originating from the peripheral lung parenchyma, and 1 had a chest wall mass.
All patients with airway lesions presented with respiratory symptoms such as dyspnea, cough, and hemoptysis in the early period of disease. Bronchosopic biopsy confirmed the diagnosis of IMBT in only 1 patient. In the others, findings were suggestive of a tumor of a bronchial gland origin, a carcinoid tumor, or leiomyosarcoma. The surgical treatment procedures are summarized in Table 2. Tracheal (or bronchial) resection and end-to-end anastomoses were performed in 6 patients who had tumors in the trachea or the main bronchi, whereas lobectomy through thoracoscopy was performed for the patient with a tumor in the segmental bronchus. The initial presenting symptoms of parenchymal IMBT were comparatively less significant. Among 7 patients, 4 underwent preoperative fine-needle biopsy, but none were definitively diagnosed (only inflammatory cells were noted in 2 cases, an inadequate specimen was obtained in 1, and some atypical cells were noted in 1). We did not try preoperative biopsy in the 3 remaining patients owing to procedural inaccessibility of the tumor. Four patients underwent wedge resections and 3 patients underwent lobectomies. One patient with bilateral lesions had serial resctions. The tumor originating from chest wall was successfully removed from the adjacent rib tissue without performing rib resection.
The tumors were completely resected in all patients, and the resection margins were confirmed to be tumor free by frozen biopsy. The patients were discharged from the hospital after the mean postoperative stay of 8.1 ± 3.6 days (range, 4 to 15). Two patients with tumors in the lower trachea underwent additional postoperative radiation therapy owing to very close resection margins. All patients had regular annual routine follow-up CT scans for a mean postoperative period of 2.7 ± 2.4 years (range, 1.2 months to 8.4 years). One patient had a local recurrence detected in the same side of the thorax on a routine postoperative CT scan, and subsequently underwent redo excision at 1.6 years.
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Comment
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Inflammatory myofibroblastic tumor in the chest is a rare finding, and making the histopathologic diagnosis is difficult when obtaining only a small biopsy tissue sample for frozen section. Inflammatory myofibroblastic tumor in the chest can be roughly classified into two groups according to location: tumors that develop in the lung parenchyma (parenchymal IMBT) and tumors that develop within the airway (airway IMBT). Previous studies have reported that most IMBTs manifest as a solitary mass in the lung parenchyma with a discrete margin [7], and only 10% of these tumors develop within the airway with early respiratory symptoms. In our sample, however, the incidence of IMBT within the airway was 46.7% (7 of 15 patients), which is much higher than previously reported. Kim and colleagues [8] reported 10% and 3.6% endobronchial and endotracheal IMBTs, respectively; and Narla and associates [2] reported that 10% of IMBTs were located in the airway.
According to our study, the two types of IMBTs clearly differ in their symptoms, diagnosis, and treatment strategy. Airway IMBT is an extremely rare disease but presents at an early stage owing to obstructive respiratory symptoms. In our cases, these airway tumors originated from the submucosal layer in the tracheal wall with broad bases and intact respiratory mucosal membranes. Eyden and coworkers [9] reported that IMBT might originate from the differentiation of quiescent fibroblasts into spindle cells, such as myofibroblasts and fibroblasts, in response to some unknown stimuli, thereby suggesting connective tissue origin of IMBT. The detection of endobronchial lesions by bronchoscopy is straightforward in airway IMBTs, but preoperative histopathologic confirmation was rather difficult. Acquiring adequate tumor tissue from the submucosal layer was technically difficult and also accompanied by high risks of bleeding due to vascularization of the tumors. Complete tumor removal with bronchoscopy or laser was also difficult, and thus surgical intervention for airway IMBT was necessary for diagnosis and treatment. Although there were anatomical difficulties in acquiring adequate safety margins in the trachea or the main bronchus, local recurrence was rare even without administering adjuvant radiation therapy. In our cases, all airway IMBTs were completely resected and there was no local recurrence during the follow-up period.
Parenchymal IMBTs in contrast were silent or manifested with vague symptoms at presentation. The mean size of parenchymal tumors was larger than that of airway IMBTs (3.3 cm versus 2.0 cm, respectively, p = 0.025; Table 2) and multiple lesions could exist. Despite parenchymal locations, the lesions were histologically similar to the respiratory mucosa in 5 of 7 patients, suggesting a close relationship between IMBT and the airway [5]. Like airway IMBT, parenchymal IMBT was also difficult to diagnose preoperatively due to tumor characteristics. Therefore, diagnosis and treatment were usually performed simultaneously with surgical procedures, for which thoracoscopic wedge resection was useful. Because IMBT is a benign lesion, additional anatomic resection and adjuvant therapy were not needed in most cases. We completely resected 7 pulmonary IMBTs without adjuvant therapy, and only 1 patient had tumor recurrence. The recurred tumor was a 9 cm mass at presentation, the largest mass in our sample, complicated with bloody pleural effusion and severe peritumoral inflammation in the left lower lobe. This patient underwent a lobectomy during the first operation; 1.6 years later, a recurrent mass was detected within the same part of the thorax, adjacent to the previous mass.
There have been reports of recurrent IMBTs. Cerfolio and coworkers [10] reported recurrence in 3 of 23 patients (13%), and Melloni and associates [11] reported 3 of 18 patients (16.7%) died of systemic metastasis or malignant transformation. Narla and associates [2] have also stated that the local recurrence rate was as high as 25%. Most recurrent cases were bilateral multiple lesions at presentation or had been incompletely resected. Recurrence after complete resection was rare [8, 9]. Based on our experiences and past reports, we believe solitary, localized parenchymal IMBTs can be treated with limited resections, in which adequate safety margins are secured. For multiple or unusually large IMBTs, careful clinical monitoring is warranted in consideration of risks of recurrence or metastasis.
As for age, 26.7% of the patients were under the age of 18 years and 53.3% were under age 40, which is comparable with the reports of Cerfolio and coworkers [10], in which 26% of the IMBT patients were under the age of 18, and Kim and associates [8], in which 55% of the IMBT patients were under 40 years. In our sample, patients with airway IMBTs were younger than those with parenchymal ones (29.2 years versus 38.5 years, respectively).
In conclusion, IMBT of the chest is a benign tumor, and usually presents as a mass in the lung parenchyma or within the airway of young patients. Inflammatory myofibroblastic tumor is difficult to diagnose with preoperative tissue biopsy, and therefore surgical diagnosis and treatment should be considered once it is suspected. Although complete resection of the tumor is crucial for continued remission, this can be achieved with a limited resection, in which an adequate safety margin is allowed but the rest of the lung is preserved. Rare exceptions may be when the mass is unusually large with invasion of adjacent tissues or when there are multiple systemic metastatic lesions. Adjunctive treatments such as radiation may be appropriate in such cases. Larger numbers of long-term follow-up cases will be needed for establishing a clear operational treatment algorithm.
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References
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Abstract
Introduction
