Histologic study with hematoxylin-eosin staining of 1 papule on the posterior trunk showed parakeratosis, flattened epidermis, hydropic degeneration of the basal layer, and a focal granulomatous inflammatory infiltrate with lymphocytes, histiocytes, and scattered multinucleated giant cells (Figure 3). The condition remained unchanged after 3 months of follow-up.
Lichen nitidus is an unusual inflammatory cutaneous condition of unknown origin. Although the disorder is more commonly confined to a small area, generalized forms of LN may be seen occasionally in children.1-3 Clinically, it is characterized by a myriad of strikingly monomorphous, pinpoint- to pinhead-sized, flesh-colored shiny papules; the surface is usually flat, but there may be a hyperkeratotic plug or a fine scale. The lesions show a predilection for the trunk, limbs, and genitalia. Facial involvement is also possible,3 and more rarely, palms, plantar areas, nails, and oral mucosae can be affected.4,5 The condition has been reported in association with Down syndrome.3,6 Lichen nitidus may be pruritic or totally asymptomatic and very often displays the Koebner phenomenon.4 Unusual clinical variants of LN include confluent, vesicular, hemorrhagic, palmar and plantar, spinous follicular, perforating, linear, and familial forms.7 The relationship of LN with lichen planus (LP) is controversial. Although there are obvious clinical and histologic differences between both entities, there are patients in whom both LN and LP coexisted, or LN progressed to LP,2 leading some authors to think that LN could be a micropapular variant of LP.8