Hydroxychloroquine withdrawal triggers pregnancy-associated pulmonary arterial hypertension in systemic lupus erythematosus: a case report and exploration of the Complement-EndMT axis.

Background: The continuation of hydroxychloroquine (HCQ) during pregnancy in patients with systemic lupus erythematosus (SLE) is a cornerstone of management, proven to mitigate maternal disease flares. However, its precise role in preventing the devastating cardiopulmonary complication of pregnancy-associated pulmonary arterial hypertension (PAH) remains inadequately defined, and the underlying pharmacological mechanisms remain largely elusive. Case presentation: We detail the case of a 31-year-old primigravida with a 15-year history of well-controlled SLE, who self-discontinued HCQ at 8 weeks of gestation. At 27 + 4 weeks, she presented with significant exertional dyspnea. Diagnostic evaluation confirmed severe PAH (estimated PASP 107 mmHg) with right heart strain, alongside serological evidence of active SLE, including hypocomplementemia. A multidisciplinary therapeutic protocol was immediately instituted, comprising the reinstatement of HCQ and the administration of intravenous methylprednisolone. This intervention resulted in a marked reduction in pulmonary arterial pressure to a moderate range (PASP 73 mmHg), stabilizing the patient's condition sufficiently to prolong gestation to 31 + 1 week, culminating in a planned cesarean delivery. At the 3-month postpartum assessment, echocardiography documented sustained improvement, with PAH decreased to a mild grade (PASP 40 mmHg). Conclusion: This case provides compelling