Are You Confident of the Diagnosis?
What to be alert for in the history
Lichen striatus is characterized by the sudden onset of symptomatic, unilateral, linear lesions in young children. There is seldom an identifiable precipitant and some will have associated pruritus, especially if there is an atopic history. Most involve the upper or lower extremity but trunk, face and nails may be involved (Figure 1).
Characteristic findings on physical examination
Linear, mostly hypopigmented, planar papules on the arm. The lines may be discontinuous and sometimes two lines parallel each other (Figure 2). V-shaped lines on the mid-back may be bilateral but unilaterality is the norm. Nails may show pitting, ridging, splitting, hyperkeratosis, leukonychia, or onycholysis.
Pathology shows epidermal hyperkeratosis, parakeratosis, necrotic keratinocytes, and mild spongiosis and exocytosis. There is a focal or lichenoid infiltrate of lymphocytes and macrophages (Figure 3). There is a superficial and deep perivascular lymphocytic infiltrate, and periappendageal involvement is common (Figure 4). No other laboratory or diagnostic tests are useful or needed.
Other linear dermatoses, particularly inflammatory linear verrucous epidermal nevus (ILVEN) enter into the differential diagnosis. ILVEN is invariably more pruritic and inflamed. Epidermal nevus has a more warty, brown appearance. Mosaic epidermolytic hyperkeratosis is a permanent fixture but can be a challenging differential diagnosis that requires biopsy. Linear lichen planus (purplish planar papules), linear porokeratosis (characteristic peripheral scale), lichen nitidus, and flat warts (both linear from koebnerization rather than blaschkoid) can usually be differentiated clinically but can be excluded by pathology.
The late hypopigmented phase of lichen striatus may look somewhat like mosaic pigment anomaly (hypomelanosis of Ito) or linear vitiligo but the history or preceding lesions in lichen striatus should be diagnostic.
Who is at Risk for Developing this Disease?
Lichen striatus affects all ages, races and geographic areas but is most common among children, with a small female predominance. The mean age is about 4 to 5 years.
What is the Cause of the Disease?
The cause of lichen striatus is unknown but the blaschkoid distribution suggests that a postzygotic mutation leads to a distinct clone of genetically altered cells that then respond to some environmental stimulus such as a viral infection or minor trauma. It has been postulated that the stimulus induces loss of immunotolerance for the abnormal clone, stimulating a T-cell mediated, auto-inflammatory response that eventually removes the clone of cells, resulting in a self-limited cutaneous response.
Rare reports of the condition occurring in siblings and in a mother and child challenge the concept of a postzygotic mutation and support Happle’s more complex theory of retrotransposons (transposable elements that make up a large portion of the human genome) causing variegated skin pathology and patterning.
Systemic Implications and Complications
There are no systemic complications associated with lichen striatus and no work-up is necessary.
Virtually all patients have spontaneous resolution within 6 to 12 months, so asymptomatic eruptions need not be treated.
Topical corticosteroids help with pruritus but do not shorten the time to recovery. I use a high-potency steroid such as clobetasol cream for 2 weeks and then just intermittently (such as weekends only) thereafter as needed.
Topical calcineurin inhibitors, tacrolimus or pimecrolimus help with pruritus but do not shorten the time to recovery. Systemic antihistamines offer minimal help with pruritus. No other systemic therapy is warranted for this harmless, self-limited condition.
Surgical and physical modalities: None
Optimal Therapeutic Approach for this Disease
Parental and patient reassurance. Leave it alone to self-resolve. Counsel that nails take much longer to normalize.
Mid-potency topical steroids such as triamcinolone and increase in potency to short 1- to 2-week bursts of a class 1 steroid such as clobetasol if there is no response. Limit treatment time and emphasize that treatment will not remove the rash or shorten its duration but will only help with itch.
Topical tacrolimus or pimecrolimus for facial lesions or areas under occlusion such as the groin or axilla or as a steroid sparing agent if prolonged therapy is needed.
Occlusion of topical therapies with saran wrap, wet gauze wrap, or Unna boot wraps for severe pruritus. Beware of induction of atrophy if topical steroids are used under occlusion for long periods.
I would never use any systemic therapy beyond a sedating antihistamine. If itch is so severe and unrelenting that a systemic agent is considered, revisit the diagnosis and make sure that there is biopsy proof that the condition is truly lichen striatus rather than ILVEN.
Long-term follow-up is not necessary and there need not be any maintenance therapy. Reassurance of the self-limited nature of the eruption is all that is generally required, but it is helpful to warn that the nails will take a long time to normalize. If topical steroid therapy is needed beyond 2 to 3 weeks, then tacrolimus or pimecrolimus should be added. A regimen of weekday tacrolimus or pimecrolimus with weekend steroid can be maintained long term but is not usually needed.
Unusual Clinical Scenarios to Consider in Patient Management
Lesions that persist beyond 2 years or those that have an unexpectedly high level of pruitus should have the diagnosis confirmed by biopsy. Relapses may occur in 4% to 5% of patients and may not be in the same location. Nail involvement may rarely precede cutaneous lesions, making diagnosis quite difficult. Whenever the correct diagnosis is in doubt, biopsy should help.
What is the Evidence?
Kavak, A, Kutluay, L. “Nail involvement in lichen striatus”. Pediatr Dermatol. vol. 19. 2002. pp. 136-8. (More prolonged course for those with nail involvement)
Patrizi, A, Neri, I, Fiorentini, C, Bonci, A, Ricci, G. “Lichen striatus: clinical and laboratory features of 115 children”. Pediatr Dermatol. vol. 21. 2004. pp. 197-200. (Largest review, more frequent in females, mostly occurring in colder months with few in summer, mostly extremities, 7 of 105 with dual, parallel bands and only 2 bilateral, 5 with relapses)
Peramiquel, L, Baselga, E, Dalmau, J, Roe, E, del Mar Campos, M, Alomar, A. “Lichen striatus: clinical and epidemiological review of 23 cases”. Eur J Pediatr. vol. 165. 2006. pp. 267-9. (Increased incidence in the summer and spring with 2 of 23 having extensive bilateral involvement, 2 presenting with vesicles and 1 having 2 episodes, 50% with personal or family history of atopy)
Racette, AJ, Adams, AD, Kessler, SE. “Simultaneous lichen striatus in siblings along the same Blaschko line”. Pediatr Dermatol. vol. 26. 2009. pp. 50-4. (Challenges the thought that lichen striatus is caused by a postzygotic mutation and adds support to Happle's theory of retrotransposons causing variegated skin patterning)
Taniguchi Abagge, K, Perolin Marinoni, L, Giraldi, S, Carvalho, VO, de Oliveira, Santini, Favre, H. “Lichen striatus: description of 89 cases in children”. Pediatr Dermatol. vol. 21. 2004. pp. 440-3. (Strong female predominance, no seasonality, incidence of atopy matched the general population)
Zhang, Y, McNutt, NS. “Lichen striatus. Histological, immunohistochemical, and ultrastructural study of 37 cases”. J Cutan Pathol. vol. 28. 2001. pp. 65-71. (Review of the characteristic pathology of lichen striatus. )
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