Correspondence Address:
Anjali Dhiman
Department of Dermatology, Venereology and Leprosy, All India Institute of Medical Sciences, Gorakhpur, Uttar Pradesh
India

Full Text



Sir,

Lichen nitidus is an uncommon idiopathic skin condition first described by Pinkus in 1907. Classical lesions in the form of tiny, skin-coloured or hypopigmented, discrete, shiny, asymptomatic papules are observed. Common sites of involvement include extremities, especially dorsa of hands, trunk and genitalia. Young adults and children are commonly affected.

The aetiology is unknown, but genetic factors are implicated as familial cases have been reported. It has been suggested that genetic predisposition renders individuals susceptible to some environmental factors that induce lichen nitidus. No specific gene has been identified so far. There is no known gender predilection. We report a very uncommon case of three first-degree relatives with lichen nitidus with onset in the second decade of life.

A 22-year-old male presented to our outpatient clinic with small white lesions over dorsal aspect of both hands and feet for the past eight years with gradual increase in the size and number of the lesions. Gradually, some lesions developed a central depression which was relatively darker in colour. The lesions were associated with mild itching. Similar lesions were present in two first-degree relatives. No systemic symptoms were present.

Cutaneous examination revealed multiple, pinhead sized to 2 × 2 mm, smooth, firm, flesh-to white-coloured papules symmetrically distributed over dorsa of hands, forearms and feet. Smaller papules were flat topped with shiny surfaces while larger lesions had central umbilication [Figure 1]. Nail plate showed longitudinal melanonychia and longitudinal ridging with no involvement of nail folds. Palms and soles were spared. Rest of the general and mucocutaneous examination was normal, and no lesions of lichen planus were seen. Similar findings were present in both his sisters [Figure 2].{Figure 1}{Figure 2}

Dermoscopy revealed smooth, white, well-circumscribed areas with central brown shadow [Figure 3].{Figure 3}

We performed a provisional diagnosis of lichen nitidus along with differential diagnosis of acrokeratosis verruciformis of Hopf, granuloma annulare, lichen sclerosus et atrophicus and frictional lichenoid keratosis and took a 4 mm punch biopsy. Histopathological examination showed epidermis with focal basal layer degeneration. We also observed abundant lymphohistiocytic infiltrate in the upper and mid dermis with focally expanded dermal papilla surrounding the infiltrate giving rise to 'claw clutching ball' appearance [Figure 4].{Figure 4}

Based on dermoscopy and histopathology examination, we performed a diagnosis of lichen nitidus.

Lichen nitidus is a rare chronic inflammatory condition with unknown aetiology. Factors responsible for this condition include autoimmunity against basal keratinocytes with altered antigenicity[1] and genetic factors. Three cases of familial lichen nitidus are already reported in the literature.[2],[3],[4] [Table 1] It is possible that the genetic predisposition renders individuals susceptible to some environmental factors that induce lichen nitidus.{Table 1}

Lichen nitidus usually presents as asymptomatic, rarely pruritic, pink to dark brown, shiny, flat-topped papules involving neck, limbs, trunk, abdomen and penile shaft. Mucous membranes and nails are rarely involved.[3] There are several morphological variants, namely, localized, generalized, plantar/palmar, linear perforating,[5] actinic,[6] haemorrhagic, vesicular,[7] mucosal and nail. Nail involvement includes longitudinal and transverse ridging, trachyonychia, nail plate thinning pits and lateral nail dystrophy.[8] Lichen nitidus often presents with lichen planus in some cases.[9]

The characteristic dermoscopic and histopathological findings can help to differentiate acrokeratosis verruciformis of Hopf from lichen nitidus. Dermoscopy of acrokeratosis verruciformis of Hopf shows papules with irregular white homogenous areas, white network and a cobblestone appearance, and histopathology shows hyperkeratosis, hypergranulosis, acanthosis, low papillomatosis and mild perivascular lymphocytic infiltration.[10] However, in the case of lichen nitidus, smooth, white, well-circumscribed 1–2 mm circular areas are seen with a brown shadow reflected through the white areas. The well-circumscribed white circular areas correlate with the epidermal acanthosis, as in histopathology. The brownish shadows correlate with the underlying epithelioid cells and lymphocytes in the dermal papilla. Histopathology shows sharply circumscribed lymphohistiocytic inflammatory infiltrate generally spanning 4–5 dermal papillae, giving a 'ball-in-clutch' configuration.

We report a case of lichen nitidus in a 22-years-old male and his two sisters aged 20 years and 24 years. We observed the involvement of dorsa of hands, forearms and feet. All three patients developed skin lesions between the age of 10 and 14 years. Dermoscopy and histopathological examination confirmed the case as lichen nitidus.

 Conclusion

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