Role of peripheral eosinophilia in adverse cutaneous drug reactions

The objective of this retrospective study was to verify whether peripheral eosinophilia (PE) may be a marker of severity for adverse cutaneous drug reactions (ACDR).

We investigated for PE in sixty-three patients diagnosed as adverse cutaneous drug reactions. All the patients underwent blood tests at baseline visit. Only patients that showed a very likely connection between ACDR and the suspected causative drug were induced in the study.

We found that 11 out of 63 patients (17%) presented PE for values ≥ 0.6 x 10(9) cells/l or for a percentage of total leukocytes ≥ 6%. These 11 patients compared to patients without eosinophilia had a longer recovery time, they showed diffuse severe cutaneous reactions and they all needed a systemic therapy compared to the 41% of patients without eosinophilia.

These outcomes prompt us to believe that peripheral eosinophilia may be an index of severity for adverse cutaneous drug reactions. Therefore, we suggest physicians to always detect the presence of peripheral eosinophilia in order to not underestimate the reaction and to promptly start an appropriate therapy.