Background
Lichen striatus is a rare, benign, self-limited linear dermatosis of unknown origin that predominantly affects children.[1, 2] It is clinically diagnosed on the basis of its appearance and its characteristic developmental pattern following the lines of Blaschko.[3]
Pathophysiology
The skin is the primary organ system affected by lichen striatus. However, lichen striatus also may involve the nails.[4, 5]
Lesions of lichen striatus follow the lines of Blaschko.[6, 7, 8, 9] Blaschko lines are thought to be embryologic in origin. They are believed to be the result of the segmental growth of clones of cutaneous cells or the mutation-induced mosaicism of cutaneous cells. In lichen striatus, an acquired event (eg, viral infection) may allow an aberrant clone of cutaneous cells to express a new antigen, resulting in the phenotypic skin changes.
Etiology
The etiology of lichen striatus is unknown. Many etiologic or predisposing factors are suggested for lichen striatus. The most commonly accepted hypothesis is the combination of genetic predisposition with environmental stimuli.
Atopy may be a predisposing factor. One group reported that 85% of patients with lichen striatus have a family history of atopic dermatitis, asthma, or allergic rhinitis. However, others have disputed this finding, stating that the incidence of atopy is no greater than that of the general population.
An autoimmune response may also be involved. Lichen striatus has been reported during pregnancy, and it has been postulated that the pregnancy may have triggered an autoimmune response leading to the appearance of the eruption.[10] In addition, lichen striatus has been reported concurrently with vitiligo[11, 12] and after adalimumab[13] and etanercept.[14] It has also been reported 17 months after allogenic peripheral blood stem cell transplant.[15] Some reports have simply suggested that lichen striatus is an inflammatory skin disease mediated by T cells.
An environmental (infectious or traumatic[16] ) etiology has been suggested as well. Familial cases,[17, 18] outbreaks among unrelated children in a shared living environment, and a possible seasonal variation suggest an environmental agent (eg, a virus). The observation of elevated interleukin (IL)-1β levels in lichen striatus biopsy specimens gave some support to the idea of infectious involvement.[7] However, results of viral testing have not conclusively proved this association. In addition, familial episodes of lichen striatus are not always simultaneous, signifying a possible genetic predisposition as a second explanation.
Lichen striatus has been reported to occur shortly after immunization with bacille Calmette-Guérin (BCG) and hepatitis B vaccination,[19] after ultraviolet (UVL) light exposure from a tanning bed,[20] after a prick from a pineapple leaf, after a sting by a bumblebee,[21] and after varicella and influenza infection.[22, 23]
One group of authors suggested that epigenetic mosaicism may be involved, hypothesizing that lichen striatus is triggered by an immunologic reaction to an infection, which triggers methylation or demethylation of a partially silenced genomic element in predisposed patients.[7] A report of concurrent pityriasis rosea and lichen striatus may lend support to this theory. Human herpes viruses 6 and 7 have been implicated in the etiology of pityriasis rosea. The concurrent lichen striatus eruption may have manifested after being triggered by this viral infection.[24]
Epidemiology
Age-, sex-, and race-related demographics
Although lichen striatus is rare in both infants and adults, the disease can occur in persons of any age.[25, 26] Primarily, lichen striatus is a disease of young children. According to some reports, more than 50% of all lichen striatus cases occur between the ages of 5 and 15 years. Other reports have disputed this age range and have claimed that the median age of onset for lichen striatus is 3 years. In a retrospective study (N = 30) of lichen striatus in children (< 18 y), Mendiratta et al found that the 0- to 4-year age group was the one most commonly affected and that the mean age at diagnosis was 5.38 ± 4.22 years.[27]
No consensus exists on sex predilection in lichen striatus. A number of studies have shown a two- to threefold increased incidence in girls as compared with boys,[1, 27] though others have shown an equal sex distribution.
No racial predilection is recognized for lichen striatus.
Prognosis
The prognosis for patients with lichen striatus is excellent. Recovery is complete. The lesions usually regress spontaneously within 1 year (range, 4 wk to 3 y). Relapses may occur, but these are uncommon. Postinflammatory hyperpigmentation and hypopigmentation may last for several months to years after lichen striatus resolves.
Lichen striatus of the nail may take a protracted course, lasting from 6 months to 5 years.[28] Nail involvement resolves spontaneously without deformity.
History
Lichen striatus often appears as a sudden eruption of small papules on an extremity. The papules are usually asymptomatic, reaching maximum involvement within several days to weeks. When patients are symptomatic, the most common complaint is pruritus. Lichen striatus is self-limited, but it may resolve with postinflammatory hyper- or hypopigmentation.[29]
Physical Examination
Lichen striatus appears as a continuous or interrupted linear band consisting of small (1- to 3-mm) pink, tan, or skin-colored lichenoid papules. The papules may be smooth, scaly, or flat-topped. Occasionally, a vesicular component is present. The band may range in width from a few millimeters to 1-2 cm and in length from a few centimeters to the full length of an extremity. The lesions are usually unilateral and single on an extremity along the lines of Blaschko (see the image below).[7, 6] In rare cases, they may be bilateral or occur in multiple parallel bands.[30, 31, 32]
View Image | Extensive unilateral lichen striatus that affects both upper and lower extremity. Grouped keratotic lichenoid papules form plaques over leg. |
The lesions are most commonly located on a proximal extremity (see the first image below) and less commonly on the trunk, head, neck, or buttock. It has been suggested that facial lichen striatus is underreported and may represent as many as 15% of all cases.[11] In darkly pigmented individuals, eruptions may appear as a bandlike area of hypopigmentation (see the second image below).
View Image | Lichen striatus over inner thigh. |
View Image | Hypopigmented lichen striatus over leg. |
Nail involvement is uncommon in lichen striatus, with only a few dozen reported cases worldwide.[5, 33, 34] Nail lesions may occur before, after, or concurrently with the skin lesions. They may also be the only area of involvement. Almost always, involvement is restricted to a single nail, and often, only the medial or lateral portions are involved.
Nail changes may include longitudinal ridging, splitting, onycholysis, nail loss, hyperkeratosis of the nail bed, thinning or thickening of the nail plate, nail pitting, onychodystrophy, punctuate and striate leukonychia, and overcurvature of the nail plate.[35, 36] Onychoscopy[37] (ie, dermoscopy of the nail) may reveal sharply marginated, deep-white structures resembling Wickham striae and brown, keratotic, cerebriform structures with pinpoint red dots surrounded by a pale halo.[38] A 2018 nail case reported longitudinal erythematous bands interrupting the lunula and extending beneath the cuticle.[39]
Procedures
Lichen striatus is generally a clinical diagnosis. Skin biopsy can be performed to confirm the diagnosis, but this is rarely necessary.
In ambiguous cases, direct immunofluorescence with staining for Civatte bodies has been proposed as a means of distinguishing between lichen planus and lichen striatus. Stains for immunoglobulin M (IgM), IgG, and complement C3 are positive in lichen planus and negative in lichen striatus.
Reflectance confocal microscopy (RCM) allows examination of the skin noninvasively with a degree of resolution approaching that of histology.[40] A retrospective study by Wang et al found that RCM could be effectively used to distinguish lichen striatus from similar-appearing linear dermatoses such as linear psoriasis, linear cutaneous lupus erythematosus, and linear lichen planus.[41]
Histologic Findings
The histopathologic results vary according to the stage of evolution. Often, a polymorphic epidermal reaction pattern with variable spongiotic and lichenoid changes is seen in lichen striatus. However, unlike lichen planus, lichen striatus may result in a dense, usually perivascular, lymphohistiocytic infiltrate that extends deep into the dermis and surrounds the hair follicles and eccrine sweat glands and ducts. Lymphoid infiltrates in the eccrine coil may mimic lupus or syringotropic mycosis fungoides, and the dense interface dermatitis may mimic conventional mycosis fungoides.[42, 43] Granulomatous inflammation may also be present.
Approach Considerations
Because lichen striatus is a self-limited disorder and because the lesions spontaneously regress within 3-12 months, treatment is typically unnecessary.[2] Reassurance of the patient and family may be all that is needed.
If associated dryness and pruritus are present, however, emollients and topical steroids may be used to treat them.[44] One report showed improvement with a combination of a topical retinoid and a topical steroid.[45] One study reported complete resolution in an adult with a short course of low-dose systemic corticosteroids[46] and another with a short course of acitretin.[47] One report described use of low-dose intralesional triamcinolone for nail lichen striatus, with complete resolution.[48]
Photodynamic therapy using methyl aminolevulinic acid has been used for the treatment of lichen striatus.[49]
Tacrolimus and pimecrolimus have been successful in treating persistent and pruritic lesions on the face and extremities.[31, 50, 51, 52, 53] Tacrolimus has also been used successfully to treat nail abnormalities in lichen striatus.[28] Oral cyclosporine has also been employed.[54]
Author
June Kim, MD, Mohs Surgeon/Dermatologist, Cascade Eye and Skin Center, PC
Disclosure: Nothing to disclose.
Coauthor(s)
Wingfield Rehmus, MD, MPH, Dermatologist, BC Children's Hospital, Vancouver, British Columbia
Disclosure: Serve(d) as a speaker or a member of a speakers bureau for: Abbvie; Valeant Canada<br/> Received honoraria from Valeant Canada for advisory board; Received honoraria from Pierre Fabre for advisory board; Received honoraria from Mustella for advisory board; Received honoraria from Abbvie for advisory board.
Specialty Editors
Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Disclosure: Nothing to disclose.
Chief Editor
Dirk M Elston, MD, Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine
Disclosure: Nothing to disclose.
Additional Contributors
Daniel J Hogan, MD, Clinical Professor of Internal Medicine (Dermatology), Nova Southeastern University College of Osteopathic Medicine; Investigator, Hill Top Research, Florida Research Center
Disclosure: Nothing to disclose.
Acknowledgements
The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors, Nelly Rubeiz, MD, and Amal Mehanna, MD, to the development and writing of this article.
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