Lichen Nitidus was first described by Pinkus in 1901. It is an uncommon, chronic, papulosquamous eruption characterized by multiple, 1-2 mm, flesh-colored, shiny, dome-shaped papules. Children and young adults are primarily affected. Pruritus is usually minimal or absent but may be more prominent in more generalized cases. Linear arrays of papules referred to as Koebner phenomenon are common, especially on the penis, forearms, and the dorsal hands.
It affects both sexes equally and occurs in all races. Lichen Nitidus has been reported associated with lichen planus, Crohn’s disease, Down syndrome, atopic dermatitis, HIV infection, juvenile chronic arthritis and congenital megacolon. There are rare variants, such as generalized Lichen Nitidus, hemorrhagic/purpuric forms, vesicular, keratodermatous (hands and feet) and perforating Lichen Nitidus. The differentiation of Lichen Nitidus from hyperkeratotic hand eczema and lichen planus of the palms is aided by the presence of a keratotic plug in the center of lesions of palmoplantar Lichen Nitidus.
HISTOLOGY: Lichen Nitidus is clinically and histologically distinct from lichen planus. Dermal papillae are widened and contain a dense infiltrate composed of lymphocytes, histiocytes, and melanophages. There is an accumulation of both CD68+ histiocytes and S-100+, CD1a+, Langerhans cells in the dermal collections. Multinucleate giant cells are often present, imparting a graulomatous apperarance to the infiltrate. The epidermal rete ridges on either side of the paplla form a clawlike collarette; referred to as a “ball and claw” deformity.
ETIOLOGY: The cause of Lichen Nitidus is unknown. Rare familial cases do occur.
TREATMENT: Most lesions are asymptomatic and resolve spontaneously without scarring. However, topical corticosteroids or calcineurin inhibitors can be used for localized disease. Narrowband UVB and PUVA can be effective in generalized cases. Therapeutic benefits have been reported from oral retinoids (acitretin). To read more about Lichen Nitidus click HERE, HERE and HERE.