Systemic mastocytosis (SM) is an abnormal proliferation of mast cells, loca
ted in different structures: skin, bone marrow spleen, liver and lymph node
s. Magnetic resonance imaging was prospectively, performed in ten patients
diagnosed by bone marrow biopsy in order to describe the different patterns
of bone marrow involvement. Coronal T1-weighted I spin-echo images were ob
tained in vertebral, pelvic, humeral and femoral bones. Depending on the ex
tension of the cell infiltration, three patterns of bone marrow involvement
were used: normal/no involvement (N), non-homogeneous (NH) and homogeneous
(H). All ten patients presented bone infiltration. The patterns observed w
ere: spine (50 % NH, 50 % H), pelvis (70 % NH), humerus 100(NH) and femur 4
0 % (NH). T1-weighted MR imaging is a sensitive technique for detecting mar
row abnormalities in patients with systemic mastocytosis. There is no corre
lation between percentage of mast cells in bone marrow biopsy and extent or
pattern of bone marrow involvement.