Two patients with mixed connective tissue disease complicated by pulmonary arterial hypertension showing contrasting responses to pulmonary vasodilators.

Mixed connective tissue disease (MCTD) involves various clinical manifestations, and pulmonary hypertension (PH) is an important organ dysfunction defining the prognosis of MCTD. The pathology of PH is heterogeneous. Here, we present 2 cases of MCTD complicated by PH that had contrasting clinical courses. The first case involved a 54-year-old woman with Raynaud's phenomenon and dyspnoea on exertion. She was diagnosed with MCTD accompanied by pulmonary arterial hypertension (PAH) and was treated with ambrisentan and tadalafil in addition to high-dose glucocorticoid (GC) therapy and rituximab therapy. After treatment, her PH resolved. The second case involved a 64-year-old woman with Raynaud's phenomenon and dyspnoea on exertion. She was similarly diagnosed with MCTD accompanied by PAH and was treated with ambrisentan and tadalafil in addition to high-dose GC therapy and cyclophosphamide pulse therapy. However, she showed exacerbation of her respiratory condition and manifestation of pulmonary veno-occlusive disease (PVOD). Thus, the treatment was discontinued, and subsequently, her condition improved and eventually returned to that before treatment. The findings suggest that the presence or absence of latent PVOD might be an important factor for predicting the therapeutic responsiveness of MCTD-associated PH. Evaluation of chest radiography findings, computed tomography findings, percent vital capacity, and percent carbon monoxide diffusion capacity might be useful for predicting prognosis and might aid in treatment. PVOD could be underlying in patients with CTD-PH. When the complication of PVOD is suggested by chest CT or pulmonary function test, we need a careful introduction with pulmonary vasodilators. So, combination therapy of pulmonary vasodilators should not be applied in all patients with CTD-PH since underlying PVOD could deteriorate the patient's condition.