Approximately 2000 patients underwent pulmonary thromboendarterectomy (PTE) to date at University of California, San Diego. We retrospectively reviewed the clinicopathologic manifestations of 200 consecutive PTE cases from June 2004 to February 2006 with an emphasis on the histopathologic spectrum of chronic thromboembolic disease. Pathology reports and all histologic sections of study cases were examined. Pertinent clinical data were obtained from operative reports and medical records. In the study group, there were 2 cases (1 man, 1 woman) of pulmonary artery sarcomas and 1 case of metastatic tumor emboli from a testicular germ cell tumor. Two patients (both women) showed histologic evidence of arteritis without clinically apparent systemic vasculitis. The remaining 195 PTE patients with chronic thromboembolic disease consisted of 97 women and 98 men with a mean age of 52 (range, 17-83) and 51 (range, 16-82), respectively. Bilateral PTE was performed in 191, and unilateral PTE was performed in 4 (right and left, 2 each) patients. History of deep vein thrombosis was noted in 38.5%, and coagulation abnormalities were documented in 16.4% of these 195 cases. Grossly, the volumes of PTE specimens were greater in men than in women and on the right side than on the left in both men and women. Microscopically, the thrombi were recent fibrinous clot in 0.8%, mixed fibrinous and organizing in 45%, and old organized in 54.2% of specimens. Inflammation within the thrombi was usually mild but moderate and severe inflammation was found in 13.4% and 1.3% of specimens, respectively. Exuberant epithelioid granulomas were seen within the thrombi in one patient who had a history of sarcoidosis. Collections of foamy histiocytes and/or cholesterol clefts were found in 45%, and calcification was present in 11.5% of specimens. One case revealed diffuse myofibroblastic proliferation in a highly inflammatory background containing numerous plasma cells, reminiscent of inflammatory myofibroblastic tumor. In summary, pathology of PTE specimens in our study group encompassed remodeling of thrombi at various stages with variable degrees of inflammation and cellularity, granulomas associated with sarcoidosis, a rare case showing features of inflammatory myofibroblastic tumor, primary or metastatic malignancy, and isolated pulmonary arteritis.