While the first issue may be tackled by using the KITD816V mutation allele burden in PB as a surrogate marker for multilineage KITD816V mutation (which was not routinely performed in this series, at the time of diagnosis),47, 48 the second issue derives from hypersensitivity to NSAIDs or other COXi being an infrequent finding in patients with mastocytosis and warrants further prospective studies in larger (e.g., multicentric) series of patients in whom diagnostic drug challenges are performed. Here, MT-CO1 is linked to mastocytosis.