대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Inflammatory pseudotumor

Radiologic Findings

Initial chest X-ray showed no definite abnormality. In CT scan, there was a soft tissue mass anteromedial aspect to the right bronchus intermedius with mild and homogenous contrast enhancement. This mass causes the luminal narrowing of right bronchus intermedius and encases the right pulmonary artery descending branch.
Our first impression was lung cancer such as squamous cell carcinoma or small cell lung cancer. Bronchoscopy was performed and there were hyperemic mucosal swelling and bronchial narrowing of bronchus intermedius due to extrinsic compression. The result of initial bronchocopic biopsy was revealed as negative finding. Thereafter, the patients underwent VATS biopsy. Deep biopsy was done twice and no malignant cell was identified at each time. On histopathologic examination, specimen was composed of lymphoplasma cells and histiocytes without remarkable increase in IgG4 positive cells. The final pathologic diagnosis was established as and inflammatory pseudotumor.

Brief Review

An inflammatory pseudotumor arising solely in the mediastinum is very rare, few cases having been reported in the literature. There is considerable diversity of appearance of inflammatory pseudotumor on CT in cases. The radiographic appearance of inflammatory pseudotumor is quite variable and nonspecific. The most common radiographic presentation is that of a solitary well-circumscribed lobulating pulmonary mass with lower lobe predominance. Lesions can have low, equal, or high attenuation compared with the surrounding tissue. Variable enhancement patterns have been described on contrast enhanced CT scans, including no enhancement, mild enhancement, heterogeneous enhancement and peripheral enhancement. Variable calcification patterns have been described on CT scans including punctuate, dense, flocculent and curvilinear. In most cases, the lesion is usually intraparenchymal with secondary compression and entrapment of bronchi occurring with growth. Occasionally, endobronchial and endotracheal lesions may cause post obstructive pneumonia or atelectasis.
Inflammatory pseudotumor (IPT) is a quasineoplastic lesion consisting of inflammatory cells and myofibroblastic spindle cells. It most commonly involves the lung and orbit but found in nearly every site in the body. They are also known as plasma cell granuloma, histiocytoma, and fibroxanthoma depending on the predominant cell type. These tumors have no sex predilection, and their peak prevalence is in the second decade of life. Cough, fever, dyspnea, and hemoptysis are the usual presenting symptoms. Although benign, they have the capacity for local invasion, rapid growth and sarcomatous transformation. Pathologically, IPTs are composed with polymorphous inflammatory cell infiltrate and variable amounts of fibrosis, necrosis, granulomatous reaction, and myofibroblastic spindle cells.

References

1.Patnana et al. Inflammatory pseudotumor: The Great Mimicker. American Journal of Radiology. 2012; 198:W217-W227
2.Agrons GA et al. Pulmonary inflammatory pseudotumor: radiologic features. Radiology. 1998; 206:511-518
3.Yoo SH et al. Inflammatory pseudotumor in the mediastinum : Imaging with 18F-Fluorodeoxyglucose PET/CT. Korean J Radiol. 2013;14:673-676.

Keywords

Mediastinum, Non-infectious inflammation,