A higher CSF protein level and number of cells per μL were observed in patients with TBM vs patients with CM, 230 (118-778) mg/dl in patients with TBM vs 58 (45-129) in patients with CM (p = 0.006), respectively 200 (9-1406) cells per μL in patients with TBM vs 60 (25-106) cells per μL in patients with CM (p = 0.013). The gene discussed is CSF2; the disease is cutaneous mastocytosis.