Complex sentence: WM is an "indolent lymphoma" (i.e., one that tends to grow and spread slowly) and a type of lymphoproliferative disease which shares clinical characteristics with the indolent non-Hodgkin lymphomas.
Split into simpler sentences: WM is an "indolent lymphoma" (i.e., one that tends to grow and spread slowly). It is a type of lymphoproliferative disease, which shares clinical characteristics with the indolent non-Hodgkin lymphomas.