Uniform granular pigmentation as a novel dermoscopic feature of drug reaction

Abstract

Objective: In clinical practice, black-brown-gray pigment granules are common under dermoscopy. However, little is known about their clinical significance. We conducted this study to investigate the dermoscopy features of drug reaction. Methods: We searched the clinical database in Xiangya Hospital, Central South University from August 2017 to August 2022. Patients with full information on pigment granules and demographic and pathological findings were entered into the final analysis. Cases were reviewed for information regarding pathological and dermoscopic patterns. Fisher’s exact test was used to examine the correlation between individual histologic variables and established diagnoses. The depth of pigment granules showed a non-normal distribution and was analyzed using a nonparametric test. Results: In total, 83 patients were included in this analysis. The presence of pigment granules under dermoscopy significantly indicated destruction of basal cells or pigment incontinence (91.5%, 76/83). The pigment granules within lesions were divided into uniform and nonuniform patterns with respect to their size, color, and distribution. Uniform granular pigmentation was more likely to be associated with eosinophils (numerous or in aggregates, P<0.001) or perifollicular inflammatory infiltration in the dermis (P=0.008). Notably, uniform granular pigmentation was more likely to be induced by medications. Conclusion: Uniform granular pigmentation under dermoscopy is a novel indicator of a drug reaction and necessitates a detailed inquiry.