Pulmonary hypertension with unclear and/or multifactorial mechanisms

5.1 Haematological disordersChronic haemolytic anaemia
Myeloproliferative disorders
5.2 Systemic and metabolic disordersPulmonary Langerhans cell histiocytosis
Gaucher disease
Glycogen storage disease
5.3 OthersChronic renal failure with or without haemodialysis
Fibrosing mediastinitis
5.4 Complex congenital heart diseaseSee the Task Force article by Rosenzweig et al. [31] in this issue of the European Respiratory Journal