Pigmented demodicidosis - an under-recognized cause of facial hyperpigmentation

Background There is a paucity of data regarding demodicidosis-associated facial hyperpigmentation. Objective To delineate the clinical, dermoscopic, and histopathologic features of demodicidosis-associated facial hyperpigmentation. Methods Clinical and diagnostic data were collected from the medical files of patients who were referred to our outpatient dermatology clinic in 2006-2019 for evaluation of facial hyperpigmentation and were diagnosed with demodicidosis. Results The cohort included 19 patients (13 male) aged 42-76 years, all with Fitzpatrick skin type 3-4. All presented with mostly asymptomatic dusky, brown-gray, facial pigmentation, localized or diffuse with background erythema in 36.8% of cases, and skin roughness in 26.3%. Dermoscopy yielded characteristic findings of white gelatinous or opaque protrusions from hair follicles or infiltration of follicular openings with an amorphic material. A specific finding was perifollicular and reticulated pigmentation of the affected areas. Findings were confirmed on microscopic (n = 7) and histopathologic (n = 5) studies. Anti-demodectic treatment led to complete (73.6%) or partial (23.4%) resolution of pigmentation within 2 years. Conclusion We describe unique clinicopathological and dermoscopic findings associated with an under-recognized type of facial hyperpigmentation caused by demodex for which we propose the term "pigmented demodicidosis." Demodicidosis should be added to the list of causes of facial hyperpigmentation.