Neutrophils in Fixed Drug Eruptions: Correction of a Mistaken Hypothesis.

ABSTRACT: Classical histopathological findings of fixed drug eruption (FDE) include a lichenoid/interface dermatitis and perivascular infiltrate in the upper and deep dermis composed of lymphocytes and eosinophils accompanied by pigment incontinence. The presence of neutrophils is also an established finding but is less investigated. Sporadic cases of "neutrophilic FDE" have been reported and suggested as a separate entity, a rare variant, or an early stage of the condition. In this article, we report 16 cases of FDE with quantitative analysis showing that neutrophils are relatively common in FDE (68.8%) and that cases with abundant neutrophils had a significantly shorter onset-to-biopsy interval (3.7 vs. 16.9 days, P < 0.023). Our findings support that neutrophilic FDE more likely represents the early phase of FDE rather than a different entity. The presence of neutrophils expands the histopathological differential diagnosis of FDE to include neutrophilic dermatosis, signifying the value of clinical correlation.