Inflammatory pseudotumor of the trachea. (Original Article).

Abstract

"Inflammatory pseudotumor" is a broad descriptive term used to describe a localized collection of inflammatory and fibroblastic cells. It is an uncommon lesion that can mimic a tumor when it is located intraluminally in the trachea or bronchi. Because an inflammatory pseudotumor has an abundance of polyclonal plasma cells, its etiology (postinflammatory vs immunologic) is still being debated. We report a new case of inflammatory pseudotumor that arose in the trachea of a 20-year-old man. We also review the histologic and clinical characteristics of this lesion.

Introduction

An inflammatory pseudotumor can be defined as a localized mass made up of a fibrous stroma and chronic inflammatory infiltrates with a predominance of plasma cells or histiocytes and an absence of anaplasia and mitotic figures. (1) These lesions can be categorized as one of three histiopathologic subtypes: (1) those that have a prominent histiocytic component (xanthogranuloma subtype), (2) those that have a prominent plasma cell component (plasma cell granuloma subtype), and (3) those that have marked sclerosing features (hyalinized sclerosing subtype). (1) Combinations of these three subtypes have occurred in some patients. (1)

These uncommon lesions usually occur in the lung parenchyma; other reported sites include the liver, kidney, thyroid, adrenal glands, and choroid plexus of the brain. (1) An inflammatory pseudotumor of the trachea is rare. In this article, we describe a new case of tracheal inflammatory pseudotumor, and we review the histologic and clinical characteristics of this lesion.

Case report

A 20-year-old white man sought evaluation for a 7-month history of progressive shortness of breath and laryngeal stridor. Bronchoscopy revealed that a tracheal mass had occluded 90% of the tracheal lumen. An endoscopic biopsy was not diagnostic.

Plain x-ray revealed a marked stenosis of the midtrachea (figure 1). Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated that a soft-tissue mass had occluded the tracheal lumen at the level of the thoracic inlet (figure 2). There was no evidence of invasion of the tracheal wall cartilage or adjacent structures. The mass was surgically resected (figure 3). On pathologic analysis, findings were consistent with those of an inflammatory pseudotumor. A terminoterminal anastomosis was performed, and the patient recovered completely. To date, he has shown no evidence of recurrence.

Discussion

The trachea and central airways are uncommon locations for an inflammatory pseudotumor. Even so, isolated cases have been reported in the parapharyngeal space and maxillary sinuses. (2-7) The etiology of these lesions is not clear. It has been postulated that they might be the result of a postinflammatory repair process, a metabolic disturbance, or an antigen-antibody interaction with an agent that was no longer identifiable in aspiration or biopsy material. Berardi et al reported that only 30% of patients with pulmonary inflammatory pseudotumor had a history of lung disease, which supports the immunologic theory. (8)

The clinical findings in a patient with an inflammatory pseudotumor are variable, depending on the growth rate of the lesion and the specific structures that have been affected. Inflammatory pseudotumors have been reported to cause chronic cough (as a result of endobronchial growth), (2) dry cough, fever, pleuritic pain, (8) right upper quadrant or epigastric pain, (1) and several constitutional symptoms, (1-5) such as malaise, weight loss, fatigue, and syncope. Inflammatory pseudotumors have been found incidentally during imaging examinations for other reasons.

In some patients, laboratory findings are normal; in others, there might be an elevated erythrocyte sedimentation rate and C-reactive protein level and sometimes a high white blood cell count. However, none of the published reports on inflammatory pseudotumor have mentioned the presence of positive tumor markers (e.g., alpha fetoproteins or carcinoembryonic antigens) in these lesions.

Microscopically, the common features of pseudotumors are dense hyalinization, fibrous proliferation, and lymphoblastic cell infiltration with histicytes, foam, spindle, and mast cells. The plasma cells contain Russell bodies and tend to be mature. No mitotic figures are found, which further illustrates the benign nature of this disease process. Immunoperoxidase tissue section staining has confirmed the polyclonal nature of the plasma cells, which are primarily positive for immunoglobulins G and A (IgG and IgA). (9) It should be noted that neither bacteria nor fungi have been shown to grow in tissue cultures. (8) Calcifications are seldom present in an inflammatory pseudotumor. When they are present, they might represent a similar but distinct pathologic entity called calcifying fibrous pseudotumor. These pseudotumors usually originate in the soft tissues of the extremities, and they exhibit extensive concentric psammomatous or dystrophic calcifications. (10)

On imaging, an inflammatory pseudotumor in the lung has been described as a well-defined and circumscribed nodule or mass. (8) Atelectasis secondary to an endobronchial inflammatory pseudotumor has also been described. (2) Pleural effusion is seldom associated with its entity, and its presence should cast doubt on the diagnosis. CT can detect calcifications that might be missed on plain radiographs, especially in calcifying fibrous pseudotumor. However, these imaging findings are nonspecific, so other diseases, including inflammatory or malignant processes, should be ruled out. An endoscopic biopsy is necessary to confirm the diagnosis. (5,6) When a patient younger than 20 years has a very slowly growing lesion, the possibility should be raised that it is an inflammatory pseudotumor.

References

(1.) Yoon KH, Ha HK, Lee JS, et al. Inflammatory pseudotumor of the liver in patients with recurrent pyogenic cholangitis: CT-histopathologic correlation. Radiology 1999;211:373-9.

(2.) Yildirim Z, Soysal O, Gokirmak M, et al. Endobronchial inflammatory pseudotumor: A cause of chronic cough. Asian Cardiovasc Thorac Ann 1999;7:326-8.

(3.) Nakayama K, Inoue Y, Aiba T, et al. Unusual CT and MR findings of inflammatory pseudotumor in the parapharyngeal space: Case report.AJNR Am J Neuroradiol 2001;22:1394-7.

(4.) Maldjian JA, Norton KI, Groisman GM, Som PM. Inflammatory pseudotumor of the maxillary sinus in a 15-year-old boy. AJNR Am J Neuroradiot 1994;15:784-6.

(5.) Oteo Dominguez JF, Yebra Bango M, Varela de Ugarte A, et al. [Endobronchial inflammatory pseudotumor: A case report and review of literature]. Arch Bronconeumol 1994;30:52-5.

(6.) Ojeda P, Ramirez JC, Alarcon A. Inflammatory pseudotumor of the trachea: Case report. Rev Col Neumologia 2000;9:274.82.

(7.) Spoto G, Jr., Rossi NP, Allsbrook WC. Tracheobronchial plasma cell granuloma. J Thorac Cardiovasc Surg 1977:73:804-6.

(8.) Berardi RS, Lee SS, Chen HP, Stines GJ. Inflammatory pseudotumors of the lung. Surg Gynecol Obstet 1983;156:89-96.

(9.) De Mascarel A, Vergier B, Merlio JP, et al. Plasma cell granuloma of the adrenal gland and the thyroid: Report of two cases. J Surg Oncol 1989;41:139-42.

(10.) Eftekhari F, Ater JL, Ayala AG, Czerniak BA. Case report: Calcifying fibrous pseudotumour of the adrenal gland. Br J Radiol 2001;74:452-4.

From the Department of Radiology, Louisiana State University Health Sciences Center, New Orleans.

Reprint requests: Enrique Palacios, MD, Department of Radiology, Louisiana State University Health Sciences Center, 1542 Tulane Ave., New Orleans, LA 70112. Phone: [phone]; fax: [phone]; e-mail: [e-mail]