Bunel V, et al. - Researchers intended to better understand pulmonary arterial histologic lesions in COPD patients with severe pulmonary hypertension (PH). Three groups of patients with COPD: severe PH-COPD (n = 10, mean pulmonary pressure (mPAP) level at rest is ≥ 35 mm Hg or ≥ 25 mm Hg with low cardiac index), moderate PH-COPD (mPAP between 25 and 34 mm Hg without low cardiac index) (n = 10), and no PH (mPAP < 25 mm Hg) (n = 10) were retrospectively compared, from the explants of patients undergoing lung transplantation. Significantly higher remodeling score of the microvessels and lower capillary density were seen in the severe PH-COPD group vs the moderate PH group. Less differentiation was offered by changes of the medium-size arteries, which were important in group 1 PH. Overall, these findings suggested a specific histologic pattern in patients with severe PH-COPD, which was different from that seen in patients with COPD with moderate PH or without PH.