Lichenoid drug rash pathology

Introduction

Lichenoid drug reactions are induced by one drug or another exogenous source that can mimic other lichenoids skin disease clinically and histologically.

Histology of the lichenoid drug eruption

In reactions to lichenoid medications, the pathology it is almost identical to lichen planus. There is a dense band lymphocytic infiltrate in dermis obscuring the dermoepidermal junction, cytoplasmic vacuolization of basal keratinocytes and apoptotic keratinocytes that degenerate into colloid bodies (Figures 1,2). Furthermore, there are generally eosinophils in the infiltrate (best seen in figure 3).

Special studies for lichenoid drug eruption.

Generally none is needed.

Differential diagnosis for lichenoid drug rash

Other diagnoses to consider include any lichenoid skin disease. The key differential is lichen planus. Clinical correlation can be very helpful. Key Histological Features Observed in the Lichenoid Drug rashes, which are not common in idiopathic Lichen planus, includes the presence of eosinophils and the presence of prominent parakeratosis.