Annular lichen planus

Annular lichen planus is a rare morphological variant of lichen planus, a chronic inflammatory disorder that primarily affects the skin. In this variant, the characteristic violaceous (purple-hued), flat-topped papules of lichen planus arrange themselves in a ring-shaped (annular) configuration, often with central clearing or atrophy. The lesions most commonly appear on the skin of the extremities, trunk, and genital areas, particularly the glans penis in males, where it is most frequently recognized. Annular lichen planus may also be referred to as ring-shaped lichen planus. The condition arises from a T-cell-mediated autoimmune response directed against basal keratinocytes in the skin, leading to inflammation at the dermal-epidermal junction. Patients typically present with well-defined annular plaques that may be pruritic (itchy) or asymptomatic. The lesions can range from a few millimeters to several centimeters in diameter. Histopathological examination reveals the classic features of lichen planus, including a band-like lymphocytic infiltrate at the dermal-epidermal junction, irregular acanthosis, wedge-shaped hypergranulosis, and civatte bodies (apoptotic keratinocytes). Treatment of annular lichen planus follows the general approach used for lichen planus and is primarily aimed at symptom relief and resolution of lesions. First-line therapy typically includes potent topical corticosteroids. Other treatment options include topical calcineurin inhibitors (such as tacrolimus), phototherapy (narrowband UVB or PUVA), and systemic therapies such as oral corticosteroids, retinoids, or immunosuppressants for refractory or widespread disease. The condition may resolve spontaneously over months to years, though recurrences are possible. Patients should be monitored for involvement of other sites commonly affected by lichen planus, including the oral mucosa, nails, and scalp.

Common questions about Annular lichen planus