Inflammatory pseudotumor of the lung: clinicopathological analysis in seven adult patients

As the origin and pathology of inflammatory pseudotumor is not clearly understood, there has recently been some confusion regarding the diagnosis of inflammatory pseudotumor.

We performed clinicopathological analyses in seven patients with inflammatory pseudotumors of the lung histologically diagnosed after surgical resection. The seven patients, selected from patients admitted to Kawasaki Medical School Hospital between April 1989 and December 2005, consisted of four men and three women (average age, 60.4 years). The detection method was from clinical symptoms in two patients and from health examinations in five patients.

Five patients had a solitary nodular shadow on chest radiographs and the other two patients had multiple shadows. Because it was difficult to distinguish pseudotumor from lung cancer by chest computed tomography in the five patients showing a solitary nodular shadow, the final diagnosis was obtained by surgical resection. In the other two patients, with multiple shadows, one of whom had nodular shadows with cavitary lesions, surgical resection was performed to distinguish the pseudotumor from metastatic lung cancer. The histological types according to the criteria of Matsubara were fibrous histiocytic in five patients, organizing pneumonia in one, and lymphoplasmocytic in one. The histological types according to the World Health Organization criteria were compact spindle-cell pattern in six patients and hypocellular fibrous pattern in one.

Because it is difficult to make a preoperative diagnosis of inflammatory pseudotumor by radiological findings or histological findings using specimens obtained by transbronchial lung biopsy, surgical resection, such as video-assisted thoracic surgery or open lung biopsy, is required to differentiate inflammatory pseudotumors from primary or metastatic lung cancers.