In both humans and mice, the clinical signs of CM progress from seizures, ataxia, and paralysis to coma and eventually death.366 However, although cerebral IE sequestration is a prominent feature of CM,364 it is a minor feature of ECM.367, 368 Intravascular accumulation of platelets and immune cells has been observed in ECM, and CD8+ cells appear central to ECM pathogenesis. This evidence concerns the gene CD8A and cutaneous mastocytosis.