[Pulmonary hypertension in autopsy cases of mixed connective tissue disease].

We histologically studied pulmonary vascular lesions of 11 MCTD autopsy cases without clinical manifestation of pulmonary hypertension (PH), and compared them with 6 advanced PH cases. Pulmonary vascular changes such as cellular intimal proliferation, intimal fibrosis, and fresh and/or organized thrombi characterized by PH were also found in non-PH cases. Furthermore, there was severe obstructive vasculopathy in small vessels of less than 100 microns in diameter, though they were not frequently observed in non-PH cases. These results suggest that morphological changes of pulmonary vessels in non-PH are qualitatively similar to those of PH. The important point between PH and non-PH cases in MCTD is whether the pulmonary arterioles over 200 microns in diameter are diffusely involved or not. The endothelial damage in the early stage, followed by microthrombi and proliferation of intimal myocytes seems to progress to severe pulmonary vascular diseases with PH.