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January - March 2006: 
Volume 19, Issue 1

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Inflammatory pseudotumor of the lung: our experience
Abstract
Inflammatory pseudotumor (IPT) is a rare benign lesion of the lung of unknown origin. We retrospec¬tively present our experience in the surgical management of ten such cases. During the period 7/1995¬6/2001, 10patients (8 males, 2 females) were operated on due to undefined pulmonary lesions that were ultimately identified as IPT. Mean patient age was 53.5±8.4years (range: 42-69years). The main clinical manifestations included haemoptysis or bloody sputum (3), and recurrent pulmonary infec¬tions (3); the pulmonary lesion was an incidental finding in 4 cases. The thorough preoperative work¬up was negative for malignancy in all cases. All patients underwent exploratory thoracotomy. Frozen sections obtained from the lesions were negative for malignancy in 2 cases and non-diagnostic in the rest. Seven lobectomies, 1 pneumonectomy and 2 wedge pulmonary resections in disease-free margins were performed. The mean postoperative period was 10.2±4.4 days (range: 6-19 days). Morbidity was 10% (due to prolonged air-leakage in 1 patient), while mortality was nil. The pathology report showed that all cases were IPTs, with a mean tumor size of 3.3±1.3 cm (range: 1-5.5 cm). In follow-up examination, all patients are alive with a mean survival of 63.1±19.7 months (range: 32-102 months), with no evidence of recurrence of the lesion. IPT is mimicking lung cancer in clinical and radiological presentations. Neither preoperative investigation, nor intraoperative frozen section pathology exami¬nation are diagnostic. The treatment of choice is surgical resection, which has both diagnostic and therapeutic value, with excellent results. Pneumon 2006,19(1):49-53.
Full text
INTRODUCTION

Inflammatory pseudotumor (IPT) represents a benign, non-neoplastic lesion of the lung of unknown origin. It was first described in 1973 by Bahabori and Liebow; other terms that have occasionally been used to describe such lesions include post-inflammatory tumor, histiocytoma, xanthoma, fibroxanthoma, xanthogranuloma, plasma cell tumor1,2.

We retrospectively present our experience in the management of ten patients with inflammatory pseudotumor, outlining diagnostic difficulties and ultimate treatment.

Figure 1. Chest radiograph showing a solitary nodule in the left lung.


MATERIAL - METHODS

In the period from 7/1995 to 6/2001, 10 patients were operated on due to undefined pulmonary lesions that were ultimately identified as IPT. The study subjects included 8 males and 2 females with a mean age of 53.5±8.4 years (range: 42-69 years). The main clinical manifestations included haemoptysis or bloody sputum (3), and recurrent pulmonary infections (3); the pulmonary lesion was an incidental finding in 4 cases (Figure 1). A detailed medical history was taken; 3 patients had chronic obstructive pulmonary disease, 3 had diabetes mellitus, and one had been operated on for breast cancer. All patients underwent a thorough diagnostic investigation, including routine laboratory examinations, fiberoptic bronchoscopy, computer tomography (CT) scanning of the chest, brain, and upper abdomen; and bone scintigraphy. An echinococcus cyst of the liver was found in 1 patient. Imaging findings were described as peripheral tumor-like lesions, without calcification; mediastinal lymph nodes were noted in 5 patients (Figure 2). The lesion was located in the left lung in 6 patients; as regards lobar involvement, in particular, the upper lobes were affected in 6 patients, the lower lobes in 2 patients; and the right median lobe and the lingula in the remaining 2 patients.

Figure 2. Chest CT showing an inflammatory pseudotumor presenting itself as a nodular density in the left lung.


Fiberoptic bronchoscopy showed no endobronchial lesion; bronchoalveolar lavage fluid showed no evidence of malignancy. Cultures for common pathogens and mycobacteria were negative. Four patients underwent fine needle aspiration (FNA) biopsy under CT guidance, which was non-diagnostic. The preoperative work-up was eventually negative for malignancy; it was then decided to proceed to exploratory thoracotomy. A posterolateral thoracotomy was performed; the pathological examination of frozen sections was negative in 2 patients and non-diagnostic in the other 8 patients. Two patients had mediastinal infiltration and 2 had pleural infiltration; in one patient, the lower lobe tumor had firmly infiltrated the upper lobe (Figures 3, 4). Seven lobectomies, 1 pneumonectomy and 2 wedge pulmonary resections in disease- free margins were finally performed.

Figure 3. Chest CT showing an inflammatory pseudotumor adjacent to the mediastinu.


RESULTS

The mean postoperative period was 10.2±4.4 days (range: 6-19 days). Morbidity was 10% due to prolonged air-leakage in 1 patient, while mortality was nil. The pathology examination showed findings consistent with inflammatory pseudotumors, with a mean diameter of 3.3±1.3 cm (range: 1-5.5 cm). The histological features of these tumor-like processes included the presence of spindle-shaped, intercalating large cells, along with in flammatory cells, plasma cells, lymph cells, as well as histiocytes (Figure 5).

In follow-up examination, all patients are alive with a mean survival of 63.1±19.7 months (range: 32-102 months), with no evidence of disease recurrence.

Figure 4. Chest CT showing a peripheral inflammatory pseudotumor adjacent to the pleura


DISCUSSION

Inflammatory pseudotumors (IPT) constitute 0.7-1% of lung neoplasms3. In the present work, we review 10 IPT cases with a mean age of 52 years; however, the majority of IPT cases in the literature are less than 40 years of age. IPT has been described as the most common benign tumor in patients aged £16 years4. No gender differences have been reported, although in our study population there is a clear predominance of males2.

The origin of the lesions is unknown. It has been reported that 33% of the patients have a history of respiratory infection or inflammatory conditions; the respective rate in our patient population was 40%5. Other possible causes include viral infections, immune responses or disorders of cholesterol metabolism. However, inflammatory pseudotumors of the lung are considered a variant process for restoring inflammatory changes rather than a true neoplasm. Immunohistochemical studies have shown the polyclonal development of plasma cells, with predominance of IgG production3.

Figure 5. The tumor margin in contiguous with the fat tissue; inflammatory infiltration consisting of lymphocytes and many eosinophils is noted. The tumor (right) shows peripheral fibrosis, whereas the center consists of myofibroblastic cells (eosin-hematoxylin stain, x100)


The majority of patients are asymptomatic; however, persistent cough, fever, dyspnea, weight loss, as well as hemoptysis or bronchitis have been reported2,5,6.

The typical radiographic finding is a solitary, well-defined density in the lower lobes of the lungs. This is in discordance with our experience; the lesion was located in the upper lobe in 6 patients. Most lesions are parenchymal, whereas mediastinal or pleural infiltration is revealed in 5% of the cases. Multiple parenchymal masses, pulmonary consolidation, atelectasis, cavitation or hilar mass are uncommon imaging findings2,7. In our patient population, both mediastinal infiltration (2) and mediastinal lymphadenopathy (5) were noted.

The diagnostic investigation, including sputum examination, fiberoptic bronchoscopy and thoracentecis under CT guidance, as well as frozen section biopsy, is inconclusive in almost all patients; this was also the case in our patient population. Surgical resection and pathological examination of the resected lung tissue provides both definite diagnosis and treatment2,3,5,6.

Macroscopic examination shows a white-yellow, welldefined lesion, lacking capsule. In microscopic examination, the lesion consists of variable combinations of fibroblasts, granular tissue, fibrous tissue and inflammatory cells, including lymphocytes, histiocytes, gigantic cells, macrophages, neutrophils, eosinophils and, typically, a large number of plasma cells8. Differential diagnosis includes lymphoma, sarcoma, malignant fibrous histiocytoma, malignant plasmacytoma and fibrosis5,6.

Surgical resection in disease-free margins through thoracotomy or thoracoscopy is the treatment of choice, since it provides radical treatment of the disease preventing recurrence2-9. Given the inability to reach a definite preoperative or even intraoperative diagnosis in the majority of the cases, pneumonectomy may also be accepted. Hence, in those cases where there is no definite diagnosis despite multimodal investigation, imaging findings are consistent with a possible malignancy, and local conditions make therapeutic excision of the lesion technically impossible (i.e. due to lesion size or location, e.g. central lesion; or due to infiltration of adjacent structures), then the minimal major resection procedure is performed, which may be a segmental resection, lobectomy or pneumonectomy2-9. Besides, excisional surgery may also be necessary for the treatment of massive hemoptysis2- 9. In cases in which an accurate preoperative diagnosis has been reached, the least extensive possible resection with uninvolved margins, e.g. wedge resection, is the preferred option. Accordingly, we performed 2 wedge resections in patients with negative frozen section examination and 8 major resections (7 lobectomies; 1 pneumonectomy) with a view to establishing an accurate diagnosis, resecting the lesion with disease-free margins, as well as managing significant hemoptysis.

Management of patients not eligible for surgical resection, patients who have already undergone partial lung resection or patients with recurrent disease, may include radiotherapy, chemotherapy or corticosteroid treatment, with controversial results10.

In conclusion, IPT is mimicking lung cancer in clinical and radiological presentations. Thorough multimodal preoperative investigation and intraoperative biopsy are non-diagnostic in the majority of cases. The treatment of choice is surgical resection, which has both diagnostic and therapeutic value, with excellent results.

REFERENCES

1. Bahadori M, Liebow AA. Plasma cell granulomas of the lung. Cancer 1973; 31(1):191-208. 2. Alexiou C, Obuszko Z, Beggs D. Inflammatory pseudotumors of the lung. Ann Thorac Surg 1998; 66:948-50.
3. Ishida T, Oka T, Nishino T, Tateishi M, Mitsudomi T, Sugimachi K. Inflammatory pseudotumor of the lung in adults: radiographic and clinicopathological analysis. Ann Thorac Surg 1989; 48:90-5.
4. Topcu S, Tastepe I, Alper A, Ozdulger A, Albayrak M, Bozkurt D, Liman T, Cetin G. Inflammatory pseudotumors of the lung: a clinical study of eleven patients. 2000; 119(1):180-2.
5. Copin MC, Gosselin BH, Ribet ME. Plasma cell granuloma of the lung: difficulties in diagnosis and prognosis. Ann Thorac Surg 1996; 61:1477-82.
6. Cerfolio RJ, Allen MS, Nescimento AG, Deschamps C, Trastek VF, Miller DL, Pairolero PC. Inflammatory pseudotumors of the lung. Ann Thorac Surg 1999; 67: 933-6.
7. Agrons GA, Rosado-de-Christenson ML, Kirejczyk WM, Conran RM, Stocker JT. Pulmonary inflammatory pseudotumor: radiologic features. Radiology 1998; 206:511-8.
8. Ferrante G, D'Armiento F, Griffo S, Gentile M, Costabile R, Cicalese M. Inflammatory pseudotumor of the lung: histomorphologic, clinical and therapeutic study. Minerva Pneumologica 2003; 42,4:223.
9. Araki K, Nakamura H, Fukui H, Ikeda M. Inflammatory pseudotumor diagnosed by thoracoscopic resections; report of a case. Kyobu Geka 2003; 56(10):893-6.
10. Urschel JD, Horan TA, Unruh HW. Plasma cell granuloma of the lung. J Thorac Cardiovasc Surg 1992; 104: 870-5.
References