Clinically, lichen nitidus presents as minute, discrete, flat-topped, shiny papules, typically less than 3
mm in diameter [5
]. Occasionally, the lesions can be dome-shaped [5
]. Although the lesions are often flesh-colored, they may be hypopigmented in dark-skinned individuals, as is illustrated in the present cases [5
]. The lesions are usually asymptomatic but may be pruritic [3
]. Sites of predilection include the chest, abdomen, genitalia, and extremities [3
]. Rarely, the palms, soles, nails, and mucous membrane may be involved [6
]. The disorder is most often localized but, rarely, can become extensive or generalized as is illustrated in the present cases [1
]. Evidence of koebnerization, with grouping of the papules in a linear array, may be seen [3
]. The diagnosis of lichen nitidus is mainly clinical, based on its distinctive features.
Lichen nitidus is an uncommon dermatosis. Data on the prevalence of this condition is very scarce. Hazen examined 11,729 Negro patients with skin diseases and found that 4 (0.034%) of them had lichen nitidus [7
]. Lapins et al. reviewed the files of the Armed Forces Institute of Pathology in Washington, DC, USA and identified 43 cases of lichen nitidus [8
]. Twenty one of these patients were Caucasian, 21 were Negro, and one was Spanish-American. Thirty four patients were male and nine patients were female. The patients ranged from 5 to 48 years of age. The 24 military male patients had a median age of 23 years, but only two of the 10 civilian patients were older than 10 years, their median age being seven years. The nine female patients had a median age of 13 years. Suffice to say, the majority of cases occur in children and young adults [4
]. The occurrence of lichen nitidus during infancy is extremely rare. A perusal of the English literature revealed but two cases [9
]. Bercedo et al. reported a girl who had generalized lichen nitidus at the age of 11 months and who developed polyarticular juvenile chronic arthritis months later [9
]. Rai and Singh described a one-month-old boy with lesions of lichen nitidus on his chin [10
]. We report two identical twins with lesions of generalized lichen nitidus noted at two months of age.
Familial lichen nitidus has rarely been reported [6
]. Marks and Jones reported two brothers, aged 10 and 12 years, with development of lichen nitidus within 2 to 3 days [11
]. Kato described the occurrence of lichen nitidus in a 33-year-old father and his 3-year-old daughter [6
]. We report the occurrence of lichen nitidus in two identical twins with onset at two months of age. Although the exact etiology is not known, the familial occurrence of lichen nitidus suggests that a genetic factor may be operative. It is possible that the genetic predisposition renders individuals susceptible to some environmental factors that induce lichen nitidus.