Classification of group 5 pulmonary hypertension according to European Society for Cardiology/European Respiratory Society guidelines

5. Pulmonary hypertension with unclear and/or multifactorial mechanisms
 5.1 Haematologic disorders: chronic haemolytic anaemia, myeloproliferative disorders, splenectomy
 5.2 Systemic disorders: sarcoidosis, pulmonary histiocytosis, lymphangioleiomyomatosis, neurofibromatosis
 5.3 Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders
 5.4 Others: tumoral obstruction, fibrosing mediastinitis, chronic renal failure, segmental pulmonary hypertension

Reproduced from [1] with permission.