Pathological Case of the Month FREE

Figure 1. Hypopigmented, flat-topped, scaly, lichenoid papules coalescing into a linear band on the right leg extending from the dorsum of the foot along the lateral aspect of the ankle.

Figure 2. Lesion extends up the lower leg to the mid thigh region.

Figure 3. A microscopic view of the lesion demonstrating spongiosis and exocytosis and a mononuclear, perivascular infiltrate in the superficial and deep dermis (hematoxylin-eosin, original magnification ×20).

Lichen striatus is an uncommon linear dermatosis of unknown origin that typically affects children between age 5 and 15 years and demonstrates a strong female predominance.¹ Although it is rare in adults, lichen striatus can occur at any age. In addition, lichen striatus develops at a higher frequency in patients with a personal or family history of atopy.² Most often, it begins with erythematous to flesh-colored, flat-topped, scaly papules that coalesce to form a continuous or interrupted band that is 1 to 3 cm in width. Lesions are typically solitary and unilateral and occur most frequently on the limbs and neck but can involve any region of the body. Occasionally, lesions may extend over the entire length of a limb and often are distributed along Blaschko lines (ie, the cutaneous lines of embryogenesis).^3- 4 Rare cases with multiple lesions distributed bilaterally have also been reported.⁵ When lichen striatus involves the nails, longitudinal ridging, splitting, fraying, onycholysis, and even total nail loss may occur.⁶

The onset of lesions in lichen striatus is usually sudden, with the eruption progressing to its fully developed form over days to weeks. Though typically asymptomatic, lesions may be associated with pruritus. The condition is self-limited, and lesions undergo spontaneous involution, typically disappearing within 1 year. Lesions resolve without scarring; however, a marked, transient postinflammatory hypopigmentation may be observed, especially in dark-skinned individuals.

The clinical differential diagnosis of lichen striatus includes linear forms of other lichenoid eruptions, including lichen planus, lichen nitidus, and lichen simplex chronicus as well as linear epidermal nevus, linear psoriasis, linear porokeratosis, tinea corporis, and verruca plana. Though lichen striatus usually resolves within a year of onset, occasionally lesions may persist for longer periods of time. In these cases, skin biopsy findings can differentiate lichen striatus from other entities such as linear epidermal nevi. Linear epidermal nevi, unlike lichen striatus, may be associated with underlying musculoskeletal, nervous, ocular, and cardiovascular anomalies and carry the potential for malignant transformation. Histopathologic features in lichen striatus include a mononuclear superficial and deep perivascular dermal infiltrate. The epidermis may demonstrate intracellular and extracellular edema with some exocytosis and parakeratosis.

Because of its benign, transitory course, treatment for lichen striatus is not indicated unless lesions are associated with considerable pruritus or pose a cosmetic concern. In these cases, a trial of topical steroids may shorten the duration of lesions.⁷

Accepted for publication November 24, 1999.

Reprints: Bernard A. Cohen, MD, Division of Pediatric Dermatology, Johns Hopkins Hospital, Brady 208, 600 N Wolfe St, Baltimore, MD 21287.