A case report of inflammatory pseudotumor of the lung: rapid recurrence appearing as multiple lung nodules.

An inflammatory pseudotumor (IPT), known as a plasma cell granuloma, is a relatively uncommon neoplasm with an unidentified etiology. To our knowledge, an early relapse with multiple lung nodules following lung resection and occurrences in multiple organs is extremely rare. The patient was a 49-year-old man who presented with left chest pain and fever. A chest film demonstrated an 8x8 cm mass in the left lower lobe. During thoracotomy in April 2001, a mass was seen to have invaded the diaphragm with remarkable pleural adhesion. The intraoperative pathological diagnosis was infiltration of inflammatory cells with no malignancy. Therefore, a partial resection of the left lower lobe was performed. Three months after the thoracotomy, a chest CT scan disclosed multiple nodular opacities bilaterally, and an open lung-biopsy of the right lung was performed in January 2002. His past history included an excision of a mass on the penis in another hospital in 1994 and a subcutaneous mass that appeared on the right thigh and disappeared spontaneously following a needle biopsy in 1999. Pathologically there was no fundamental difference among his present lesion and the former two. The pathological diagnosis at each occurrence was inflammatory pseudotumor (IPT). In immunohistochemical study, the staining with smooth muscle actin cells was positive, but was negative for the staining with anaplastic lymphoma kinase (ALK). With no evidence of a neoplastic process, these histopathological and immunohistochemical findings could imply that this case may be a postinflammatory reparative reaction, although his condition exhibited the clinically aggressive behavior of suspected lung metastasis.