INFLAMMATORY SARCOMATOID CARCINOMA OF THE LUNG - REPORT OF 3 CASES AND CLINICOPATHOLOGICAL COMPARISON WITH INFLAMMATORY PSEUDOTUMORS IN ADULT PATIENTS

Although the capacity for some pulmonary carcinomas to mimic sarcomas is well recognized, their potential resemblance to selected benign les ions of the lung is currently underappreciated. The authors herein rep ort three examples of sarcomatoid bronchogenic carcinoma with a decept ively bland appearance and an investment of reactive inflammation, suc h that they resembled pseudotumors histologically. These lesions occur red in two men and one woman who were 44, 61, and 63 years old, respec tively, at diagnosis. All patients presented with a productive cough, hemoptysis, or chest pain. Their pulmonary masses were irregularly mar ginated radiographically, and ranged in size from 2.5 to 5.5 cm. Two w ere treated with lobectomy, and one underwent a wedge excision, follow ed by radiotherapy to the thorax. Despite these measures, each patient with inflammatory sarcomatoid carcinoma (ISC) died of disease or is l ikely to do so. Microscopically, ISCs were composed of uniform spindle cell proliferations with only modest nuclear pleomorphism, limited mi totic activity, and an arrangement in fascicles, storiform configurati ons, or haphazard arrays. Lymphocytes and plasma cells were interspers ed throughout each of them, and keloidal stromal collagen was apparent internally in two examples. Two of the neoplasms also invaded pulmona ry blood vessels or bronchi. A comparison group of 10 adults with pulm onary inflammatory pseudotumors (IPs) of the fibrous histiocytoma type shared several clinical attributes with ISC and showed closely simila r histological features, except that the IPs lacked mitoses and invasi veness, and contained xanthoma cells or multinucleated elements in som e cases in this series. lmmunohistochemical analyses showed consistent dissimilarities between ISC and IF; keratin and epithelial membrane a ntigen were present in ISC but not IF, whereas actin was observed only in the proliferating spindle cells of IF. In summary, the potential c linicopathologic overlap between ISC and IP suggests that caution shou ld be exercised in the separation of these two lesions. In particular, it is unwise to attempt to make this distinction in ten intraoperativ e frozen section setting. Copyright (C) 1995 by W.B. Saunders Company