Pulmonary extra-medullary hematopoiesis and pulmonary hypertension from underlying polycythemia vera: a case series

Myeloproliferative neoplasia (MPN)-associated pulmonary hypertension (PH) is included in group five of the most recent clinical classification of PH.(1) The MPNs are a heterogeneous group of disorders that includes disorders with primary expression of a myeloid phenotype and disorders characterized by expression of the Janus Kinase 2 (JAK2) mutation, p.V617F. The latter includes essential thrombocytosis, polycythemia vera, and idiopathic myelofibrosis.(2) Pulmonary extra-medullary hematopoiesis (EMH) refers to the presence of hematopoietic precursor cells in the lung. It is a rare complication associated with myelofibrosis. Here we present a case series highlighting the clinical–pathological–radiological features of pulmonary EMH and PH from underlying polycythemia vera.