Linear papular eruption grows on boy’s neck

The Case

A father brings his 12-year-old son to the clinic for evaluation of a skin eruption that has been on the back of the boy’s neck for a year, but which just began to extend behind his ear. The rash is asymptomatic, and the otherwise healthy patient is annoyed that he has to spend a beautiful morning in a physician’s office. 

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DERMCASE diagnosis: Lichen striatus

In 1901, in the then-German city of Breslau situated along the River Odra, skin and venereal disease expert Alfred Blaschko presented his report, Nerve Distribution in the Skin in Relation to Diseases of the Skin, to the German Dermatological Society Congress.¹ Blaschko explained to those gathered that the curious lines of distribution seen in certain dermatological conditions correspond to the developmental pattern of skin cell precursors. This phenomenon is now known as the lines of Blaschko.

Epidemiology and clinical findings

Lichen striatus (LS), a common, asymptomatic, self-limited skin disease of unknown etiology that is most commonly found among children aged 5 to 15 years, is just one of many conditions that follow this Blaschkoid pattern.²

Next: Bald area on back of a girl's scalp

Lichen striatus is characterized by flesh-colored to purple erythematous, discrete, and confluent flat-topped papules with fine overlying scale that form a linear unilateral plaque.² The best-studied risk factor for LS is atopy, present in 20% to 85% of cases.³ Xerosis, vitiligo, and pityriasis alba also have been associated with LS.²

Lichen striatus manifests on the face in 3% to 15% of cases in children, with some reports stating that it is probably even more common than many estimates suggest.^2,4 However, the location of LS seems to have little effect on its natural history. Onset is usually sudden, with progression over days or weeks, and spontaneous regression is gradual, within 6 to 24 months. Resolution leaves a transitory residual hypopigmentation that is most prominent in those with a dark complexion, such as this patient.

Differential diagnosis

Lichen striatus should be considered in any child with an acquired papular eruption on the face following the lines of Blaschko. Differential diagnosis may include multiple linear papular eruptions, including linear lichen nitidus, linear psoriasis, lichen planus, and blaschkitis, to name a few,^2,3 yet LS, particularly facial LS, should be considered clinically given that its histologic features are not specific.

Laboratory findings

In atypical cases, however, biopsy may be indicated. Histology shows superficial and deep perivascular lymphocytic infiltrate, hyperkeratosis, mild spongiosis with lymphocytic exocytosis, and appendageal involvement.^4,5

Treatment and outcome

Treatment of facial LS with topical steroids is controversial, and nonsteroidal topical therapy has limited supporting data. Therefore, observation of the self-limiting condition was recommended to the patient, accompanied by administration of sugar-free, organic lollipops.

REFERENCES

1. Blaschko A. Die Nervenverteilung in der Haut in ihrer Beziehung zu den Erkrankungen der Haut: Bericht erstattet dem VII.Congress der Deutschen Dermatologischen Gesellschaft, abgehalten zu Breslau 28-30. Mai 1901. Berlin: Wien, Leipzig, W. Braumèuller; 1901.

2. Mu EW, Abuav R, Cohen BA. Facial lichen striatus in children: retracing the lines of Blaschko. Pediatr Dermatol. 2013;30(3):364-366.

3. Peramiquel L, Baselga E, Dalmau J, Roé E, del Mar Campos M, Alomar A. Lichen striatus: clinical and epidemiological review of 23 cases. Eur J Pediatr. 2006;165(4):267-269.

4. Zhang Y, McNutt NS. Lichen striatus. Histological, immunohistochemical, and ultrastructural study of 37 cases. J Cutan Pathol. 2001;28(2):65-71.

5. Litvinov IV, Jafarian F. Images in clinical medicine. Lichen striatus and lines of Blaschko. N Engl J Med. 2012;367(25):2427. 

Mr Simkin is a fourth-year medical student at Johns Hopkins University School of Medicine, Baltimore, Maryland. Dr Oyesanya is a second-year (PGY-3) resident in Dermatology, Johns Hopkins University School of Medicine, Baltimore. Dr Cohen, section editor for Dermcase, is professor of Pediatrics and Dermatology, Johns Hopkins University School of Medicine, Baltimore. The authors have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to allow the authors to focus on key teaching points. Images also may be edited or substituted for teaching purposes.