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Case Reports

Abstract

Lichen striatus (LS) is a self-limiting, linear inflammatory dermatosis that typically presents on an upper or lower extremity and follows the lines of Blaschko. It is most often seen in children, while adult-onset cases are rare. The etiology remains unclear, with proposed mechanisms including autoimmune triggers, vaccine-related immune stimulation, post-infectious processes, and cutaneous mosaicism. Spontaneous resolution is well recognized. A 63-year-old woman presented with a new-onset eruption of a well-circumscribed figurate erythematous scaly plaque on the mid-lower back. The patient first noted the rash shortly after a COVID-19 infection, though she acknowledged it may have been present for several months prior. Punch biopsy demonstrated a lichenoid infiltrate with sawtooth hyperplasia of the epidermis, wedge-shaped hypergranulosis, and perieccrine lymphocytic inflammation. A diagnosis of LS was favored, and the patient was treated with topical steroids. Complete resolution was observed two years later. Although LS is more common in children and on the extremities, recognition of its occurrence in adults and in atypical locations is important. Awareness of the benign, self-limiting nature of LS is important to prevent unnecessary intervention. This case adds to the limited literature on adult-onset lichen striatus. The temporal association with COVID-19 infection, in line with limited prior reports of vaccine-related and infection-related cases, suggests COVID-19 as a potential trigger in the onset of LS.