Isolated pulmonary Takayasu arteritis: clinicopathologic characteristics.

Involvement of the pulmonary arteries is common in systemic Takayasu arteritis and, in nearly all of the reported cases, the diagnosis has been based solely on clinical and angiographic evaluations of the patients. Isolated pulmonary Takayasu arteritis occurs rarely and can be diagnosed only after histologic examination of the appropriate tissue specimens; five such patients are described herein. The patients were two men and three women. Their age at diagnosis ranged from 25 to 66 years. The initial clinical diagnosis was thromboembolism in two patients, and primary pulmonary hypertension, pulmonary granulomatosis, or pulmonary tumor or sarcoidosis in the remaining three patients, respectively. All five patients underwent surgery for lung resection (three patients) or for reconstruction/bypass of the obstructed pulmonary arteries (two patients). Three types of vascular lesions were observed in the surgical specimens: the classic large-vessel granulomatous giant cell arteritis, a peculiar type of organized thrombus with prominent recanalization and neoangiogenesis, and plexogenic arteriopathy. Thus, the histopathologic findings of pulmonary Takayasu arteritis is distinctive and differs in many aspects from that of systemic Takayasu arteritis. Moreover, the vascular lesions of pulmonary Takayasu arteritis are distinguishable from those of pulmonary hypertension, sarcoidosis, and other types of pulmonary angiitis and granulomatosis.