Late‐onset pulmonary arterial hypertension in association with graft‐versus‐host disease after allogeneic stem‐cell transplantation

Pulmonary arterial hypertension (PAH) has been reported only rarely after allografting. Cases have all been in young patients, occurred within 6 months of transplant and been attributed to direct toxicity of chemoradiotherapy on the pulmonary vasculature. This case describes the late onset of PAH in a 36-year-old woman on a background of acute and chronic graft-versus-host disease (GVHD). Open lung biopsy demonstrated medial hypertrophy and intimal proliferation in small pulmonary arteries and arterioles, with no evidence of secondary causes such as thromboembolism, vasculitis, interstitial lung disease, or obliterative bronchiolitis. Therapy with bosentan produced symptomatic improvement. While the possibility of coincidental "idiopathic" PAH cannot be excluded, the clinical context suggests that pulmonary vessels may be a target for GVHD post-allograft.