Clinicopathological characterisation of myeloproliferative neoplasm?unclassifiable (MPN?U): a retrospective analysis from a large UK tertiary referral centre

Myeloproliferative neoplasm-unclassifiable (MPN-U) presents an MPN-type phenotype that fails to meet diagnostic criteria for other MPN variants. Variability in the clinicopathological phenotypes many challenges. Amongst a registry cohort of 1512 patients with MPN, 82 MPN-U were included, median (range) age 49·7 (13–79) years. Albeit heterogeneous, common presentation features included raised lactate dehydrogenase, thrombocytosis and clustered/pleomorphic megakaryocytes on trephine biopsy. Thrombosis was (21%), necessitating vigilance. The event-free survival 11·25 years (95% confidence interval 9·3–not reached), significantly shortened cases lower platelet counts (<500 × 109/l) leucocytosis (?12 at presentation. Generation potential prognostic scores is required.