Inflammatory pseudotumors (IPs) are rare benign tumors of unknown etiology. They comprise 0.4% to 1% of all pulmonary tumors. With no sex predominance, they can occur at any age, but most commonly appear in childhood or early adulthood.1,2 These tumors develop in the lungs more frequently than the other sites, such as the larynx, gastrointestinal system, retroperitoneal area, genitourinary system, central nervous system, and the orbits.3,4
Morphologically, they are well-circumscribed, unencapsulated, and vascularized tumors. In addition to the absence of mitosis, their histologic pattern is characterized by inflammatory cells, collagen, mature fibroblasts, and benign mesenchymal cells.1–3 The subgroups of the IPs named by the dominant cell type are inflammatory myofibroblastic tumor (IMT), plasma cell granuloma, histiocytoma, fibroxantoma, xantogranuloma, and plasma cell histiocytoma complex.2,3 The current case is an IMT located bilaterally in the lung parenchyma.
A 21-year-old woman presented with nausea, vomiting, decrease in appetite, a 13-pound weight loss over the past 6 months, and right-sided chest pain of 5 days' duration. Her past and family histories were unremarkable. She was married, had 3 children, and gave a 3-pack-year smoking history. Earlier diagnostic work-ups had not been conclusive. She was referred for the further evaluation of bilateral lung lesions as seen on her chest x-ray. On physical examination, her blood pressure, body temperature, and pulse rates were within normal range. She had a pale appearance, in addition to increased dullness on percussion and reduced tactile vocal fremitus and breath sounds over the posterior, lower right hemithorax.
Her laboratory examination was as follows: erythrocyte sedimentation rate: 96 mm/hour, white blood cell count: 10,900 mm3, red blood cell count: 3,950,000 mm3, hemoglobin: 9.5 g/dL, hematocrit: 30%, platelets: 571,000 mm3, and serum albumin: 3.3 g/dL. Other routine biochemical tests were within normal ranges. Her posteroanterior chest x-ray depicted a right-sided 6-cm paracardiac mass that did not silhouette the borders of the heart. There was also a left-sided ill-defined, peripheral, and heterogeneous increase in density that superposed the left fouth rib and the third and fourth intercostal areas (Fig. 1). Computed tomography (CT)-guided transthoracic needle aspiration biopsy of the right pulmonary lesion was performed on an outpatient basis. Cytologic examination of the aspiration specimen was reported as “spindle cells; suspicious for spindle cell tumor.” She was hospitalized for further diagnostic work-up.
Thoracic CT further confirmed that the right pulmonary mass extended from the apical to the posterior basal segment of lower lobe abutting the pleura and had necrotic and solid components (Fig. 2A). There was a minimal right pleural effusion and a peripheral 2-cm cavitary nodule located in the inferior lingular segment (Fig. 2B). Positron emission tomography integrated CT scans were obtained, which revealed increased fluorodeoxyglucose uptake in both pulmonary lesions, subaortic lymph nodes, and gastric wall suggestive of malignancy.
The tissue specimen obtained by ultrasonography-guided transthoracic cutting needle biopsy from the right pulmonary mass was pathologically assessed as “inflammatory myofibroblastic tumor” (Fig. 3A). Biopsy from the stomach wall obtained at esophagogastroscopy showed erythematous gastritis.
At flexible bronchoscopy, compression of subsegmental bronchi in the posterior basal segment of the right lower lobe was noticed along with mucosal hyperhemia and edema of the inferior lingular bronchus. Transbronchial 19-gauge needle aspiration from the right lower lobe of this area revealed “nonspecific inflammatory cells,” and bronchial aspiration fluid cytology was benign. Bronchoalveolar lavage fluid and brush biopsy specimens obtained from the inferior lingular segment both yielded “mixed inflammatory cells.” There was no growth on the cultures of the bronchial aspiration and bronchoalveolar lavage fluid samples.
The patient underwent right lower lobectomy. Pathologic examination of the surgical specimens confirmed IMT (Fig. 3B) and reactive lymph nodes, respectively. Vimentin-positive and CD45-positive and pancytokeratin and calretinin-negative immunohistochemical staining of the tumor tissue further confirmed it as a spindle cell tumor (Fig. 3C).
The chest x-ray and thoracic CT scans obtained at 1 month following the thoracotomy showed spontaneous and almost complete resolution of the peripheral cavitary nodule in the lingula. The patient is being followed up at 3-month intervals. One year after the surgery she has no complaints, no recurrence has been detected on her thoracic CT scans, and laboratory test results have remained within normal range.
Despite the absence of a definite etiology, one of the suspected factors in the development of IP is pulmonary infection in at least 30% of the patients. Viral infections with Epstein-Barr virus have been blamed in some cases. Metabolic disturbances, antigen-antibody reactions, immune disturbances, earlier radiotherapy, local trauma, and hemopoietic stem cell transplantation have also been suggested in some others.1,3,5 A clonal chromosomal rearrangement involving chromosome band 2p23 that targets anaplastic lymphoma kinase gene has been frequently shown, particularly in young adults and children with IMTs.6 In our case, we could not define any specific etiologic factor either from her history or laboratory tests.
Most common symptoms and signs in IP are cough, chest pain, dyspnea, hemoptysis, anorexia, arthralgia, fever, and clubbing, whereas some cases can be asymptomatic.2,4,5,7 Our patient, in addition to a local symptom (chest pain), also had systemic symptoms (nausea, vomiting, decrease in appetite, and weight loss). Anemia, thrombocytosis, high erythrocyte sedimentation rate, and polyclonal hypergammaglobulinemia can be determined on laboratory analysis.3,5,7 The current patient had a high erythrocyte sedimentation rate, anemia, mild thrombocytosis, and hypoalbuminemia.
Although benign, IPs can show local invasion to neighboring structures, particularly vertebral bodies and thoracic vessels. Extrapulmonary IPs behave more aggressively with frequent local recurrences. Recurrence and multifocality can be seen in 8% to 24.5% of IPs. Recurrences may occur at 1 to 24 months.3,5,8 IP can grow fast and show sarcomatous or lymphomatous transformation.3,5,9 There was no invasive behavior of the IP in the current case; however, the right pulmonary mass was resected for its possible malignant transformation in the future.
Radiologically, an IP is frequently a solitary and well-circumscribed nodule or mass closely related to the airway. It frequently has heterogeneous attenuation and calcification foci. Its diameter is usually 0.5 to 5.5 cm, but occasionally may be as large as 36 cm. Rarely, there can be multiple nodules or masses, central cavitation, hilar lymphadenopathy, mediastinal mass, atelectasis, and consolidation. However, pleural effusion has not been shown.1,5,10 Our patient had bilateral pulmonary lesions: a right-sided 6-cm mass with heterogeneous attenuation, and a left-sided cavitary 2-cm nodule with no calcification foci in either lesions. There was subaortic lymph node involvement and minimal right pleural effusion.
The most frequent site for IPs is the lung parenchyma.1,3,5,7 However, endobronchial or endotracheal involvement is rare.5,10 Mediastinum, larynx, gastrointestinal system, retroperitoneal area, genitourinary system, central nervous system, and orbits can also be involved.3–5 Our patient had bilateral parenchymal, but no endobronchial lesions. On positron emission tomography integrated CT scans, there was increased fluorodeoxyglucose uptake in a subaortic lymph node and the wall of the stomach. However, specimens obtained by mediastinal lymph node dissection and gastroscopic biopsy did not show IP.
Differential diagnosis of IP includes mesenchymal malignancy (particularly sarcoma), spindle cell squamous carcinoma, lymphoma, hamartoma, chondroma, granuloma, sclerosing hemangioma, carcinoid tumor, neurofibroma, and nodular fasciitis.1,3,5,11 In our patient, considerable weight loss, anemia, a 6-cm mass and a contralateral nodule, all together, increased the suspicion for primary or metastatic malignancy although a diagnosis of IMT was obtained by transthoracic cutting needle biopsy. Thus, surgical resection was performed to obtain the definite diagnosis.
Resection of IPs is the treatment of choice.1,5,7,11 The right pulmonary mass was resected first in the current case for both diagnostic and therapeutic purposes. We intended to resect the nodule in the left lung at another session after confirming the diagnosis of IP.
Three-year and 5-year survival rates after complete resection are 82% and 74%, respectively. In cases with incomplete resection, tumor recurrence, and candidates who are unsuitable for surgery, corticosteroids, nonsteroidal anti-inflammatory drugs, radiotherapy, or chemotherapy have been used with varying degrees of success.1,4,5,12
Particularly in cases in which preservation of the lung tissue is required, obstructive IPs in the trachea or central bronchi can be ablated by interventional bronchoscopic methods such as laser, electrocauterization, and/or mechanical debulking for palliation.5
Prognosis of IP varies. There can be recurrence after surgery or steroid treatment. Some cases may show spontaneous resolution without any treatment. In some other cases, synchronous or metachronous multifocal behavior can be observed.1,3,5,12 Mortality (9.4%) is due to local complications or treatment regimen.5,7,11,12 In this case, 1 month after the resection of the right pulmonary mass, the left pulmonary nodule was found to have resolved spontaneously, obviating its planned resection. The chest x-ray taken on the 10th postoperative day showed the nodule was still stable. Furthermore, no corticosteroid or nonsteroid anti-inflammatory treatment was prescribed before, during, or after the surgery. The patient has been asymptomatic and has had no recurrences or new foci within the 12-month follow-up. She will be followed up closely in the outpatient department.