Pediatric emergency medicine trisk 1848 1848

Lichen Planus
Lichen planus is seen occasionally in pediatric patients as a chronic, pruritic,
reddish-blue (violaceous) to purplish eruption. Two percent to 3% of cases occur
in patients younger than 20 years of age.

FIGURE 88.26 Purple polygonal papules consistent with lichen planus.

The eruption generally involves the flexors of the wrist, forearms, and legs,
especially the dorsum of the foot and ankles. The highly pruritic lesions appear as
small, violaceous, shiny, flat-topped, polygonal papules ( Fig. 88.26 ). These
qualities may be recalled with the alliterative mnemonic of the five p’ s: p ruritic,
p urplish, p lanar, p olygonal, p apules. Some add a sixth p indicating a
predilection for so-called “private” areas such as penis or vulva. The surface of
these papules may have white cross-hatching, called Wickham striae. Lesions
may occur in sites of trauma or injury (Koebner phenomenon). The scalp may be
involved, often resulting in a scarring alopecia, called lichen planopilaris. It is
important to examine the buccal mucous membranes and the genital areas for a
reticulated or lace-like pattern of white papules or streaks. This finding is
characteristic for lichen planus. The nails are often pitted, dystrophic, or ridged
(pterygium nails). The lesions in lichen planus can be vesicular or bullous.
Hypertrophic and linear lesions occur but are less common. Persistent, severe,
postinflammatory hyperpigmentation is common in African Americans. In twothirds of patients, the lesions clear within 8 to 15 months. The cause of the
disorder is unknown. Topical therapy with steroids can be helpful, and treatment
with oral steroids may be necessary for extremely symptomatic patients. For