WHO subvariants of indolent mastocytosis: clinical details and prognostic evaluation in 159 consecutive adults

Abstract

To the editor: The 2008 World Health Organization (WHO) proposal recognizes 2 provisional indolent systemic mastocytosis (ISM) subvariants: smoldering systemic mastocytosis (SSM) and isolated bone marrow (BM) mastocytosis (BMM).[1][1] SSM is characterized by a high burden of mast cells (MCs; [Table