Safety of Drug Provocation Tests in Adults With and Without Clonal Mast Cell Disorders

Mastocytosis is a clonal mast cell disorder (CMD) characterized by the proliferation and accumulation of mast cells (MC) in different tissues. Anaphylaxis, resulting from massive MC activation and mediators' release, is reported in 22%-49% of mastocytosis cases, with drugs being potential triggers. Proper counseling on drug safety is crucial. We aim to demonstrate that, after a careful evaluation of clinical history and allergic work-up, drug provocation tests (DPT) are a safe and effective diagnostic tool in patients with CMD.

We enrolled 104 CMD patients with a suspicion of drug hypersensitivity reactions (DHR) or without known tolerated drugs and 100 control patients with DHR. The types of DHR and the results of DPT were compared between CMD and control groups.

In both groups, previous DHR was mostly represented by skin reactions (46.4% in CMD and 82.9% in the control group); the most involved drugs were aminopenicillins and nonsteroidal anti-inflammatory drugs (NSAIDs). We performed 250 DPTs in the CMD group and 231 in the control group; challenges were well tolerated in both groups, except for 6 skin reactions: 1 in the CMD group (1.0%) and 5 in the control group (5%).

Drug challenge is a safe and effective diagnostic tool in patients with CMD. Moreover, patients that have never had adverse reactions to NSAIDs or antibiotics before the diagnosis of CMD do not need to undergo challenge tests. In contrast, patients with a history of reactions should avoid the culprit drugs and undergo DPT to identify a safe alternative drug.