A 51-year-old man, with skin type V according to the Fitzpatrick scale, with human immunodeficiency virus (HIV) infection currently receiving highly active antiretroviral therapy, and with an undetectable viral load, presented with a 3-week history of asymptomatic lesions on his back and arms. Clinical examination revealed multiple pin-point, round, white-colored, flat-topped papules, some clustered, and others arranged linearly (Fig. 1A). Dermoscopic examination uncovered several white, well-circumscribed, circular areas measuring 0.5-1 mm in diameter, characterized by a smooth surface with a central brown shadow (Fig. 1B and C). Histopathological analysis of a biopsy specimen revealed epidermal hyperplasia encompassing a central area of atrophy and erosion. This was accompanied by a focal dense lymphohistiocytic infiltrate in the upper dermis, with surrounding hyperplastic rete ridges forming a distinctive “ball and claw” configuration (Fig. 1D). These findings were consistent with a diagnosis of lichen nitidus (LN).

Figure 1 Lichen nitidus. A: numerous pinhead-sized white papules on the flexural aspect of the arm, some clustered and some in a linear distribution. B and C: dermoscopy of multiple white, well-circumscribed, circular areas measuring 0.5-1 mm in diameter, characterized by a smooth surface with a central brown shadow – clustered (B) and linearly (C) (DermLite DL4; polarized, ×10). D: histopathologic picture revealing epidermal hyperplasia surrounding a central zone of atrophy and erosion; focal dense lymphohistiocytic infiltrate in the upper dermis, with surrounding hyperplastic rete ridges in a “ball and claw” configuration (H&E, ×40). 

LN is an uncommon idiopathic chronic eruption with an unknown etiology and pathogenesis. Predominantly, LN cases manifest in pediatric and young adult populations¹. It presents with multiple small, uniform, shiny, and asymptomatic papules, typically localized in the flexor aspects of the upper extremities, abdomen, and genitalia¹,². The Koebner phenomenon serves as a hallmark of LN³. Dermoscopy proves to be a valuable tool, revealing well-demarcated, smooth, white circles with a discernible brownish shadow within⁴. A definite diagnosis, as described in the reported case, relies on histopathological evaluation²,³. Given its typically asymptomatic nature and tendency to spontaneous resolution within months to a year, treatment primarily targets symptomatic or generalized cases of LN. Therapeutic options include topical corticosteroids, topical calcineurin inhibitors, oral antihistamines, and phototherapy¹. It is imperative to provide patients with reassurance regarding the benign yet chronic course of this condition. This case underscores the importance of considering LN in HIV-positive patients and highlights the utility of dermoscopy in its diagnosis. Clinicians encountering similar presentations should consider LN in their differential diagnosis.