Inflammatory Pseudotumor of the Lung: Three cases report

Kim, Hye Soog; Hur, Bang; Chang, Hee Kyung; Hur, Man Ha

Abstract

The inflammatory pseudotumor of the lung is a non-neoplastic pulmonary mass lesion, composed of a variey of inflammatory cells including plasma cells, histiocytes(often xanthomatous), mast cells, lymphocytes, and spindle shaped mesenchymal cells. Although the pathogenetic etiology of this lesion is not estabilished, it has been claimed that it is associated with local inflammatory reaction. From 1984 to 1986, we experienced three cases of pathologically confirmed inflammatory pseudotumor of the lung. All three cases revealed similar gross and microscopic features, with only minor differences in components on microscopic level. All specimens were products of lobectomy. They showed a relatively well defined, yellowish white and solid mass, measuring about 5.0 cm in diameter. Histologically, the lesions, which were well demarcated from the uninvolved region, were characterized by dense infiltration of plasma cells and xanthomatous histiocytes admixed with lymphocytes, spindle shaped mesenchymal cells and polymorphonuclear leukocytes. At periphery, bronchi and bronchioles were entrapped by these cells. In focal areas, spindle shaped mesenchymal cells were aggregated, resulting in formation of thick bundles in which plasma cells were infiltrated. In case 1 and 2, myxoid change of stromal tissue was noted. Also noted were foci of osteoid metaplasia of the stromal layer in case 1. The authors report three cases of inflammatory pseudotumor of the lung, with comparative observation of each case, associated with literature review, with emphasis on the pathogenesis of this rather infrequent lesion. And some reviews were made on differential diagnosis between inflammatory pseudotumor and non-neoplastic or neoplastic lung mass including so called sclerosing hemangioma.