Linear Rash on the Arm of a 7-Month-Old Girl

Dermclinic

A 7-month-old girl presented with a 2-month history of rash. The rash, which had first appeared as small, papular lesions on the left antecubital region, had spread in a linear fashion distally to the wrist and proximally to the axillary region. No vesicles were present. The rash did not appear to bother the infant, and the parents reported no history of apparent itchiness. The girl had no history of injury, contact with an irritant, exposure to persons with chickenpox or shingles, or exposure to insects.

Physical examination revealed red papules measuring approximately 1 to 3 mm in diameter, with a linear distribution along the lines of Blaschko. The rash appeared as a thin band extending from the left axillary region to the left wrist. No nail involvement or vesicles were noted. The rest of the physical examination findings were normal.

Based on the clinical presentation of this rash, what is this infant’s diagnosis?

(Answer and discussion on next page)

ANSWER: Lichen striatus

Lichen striatus is a relatively rare, benign, and self-limiting dermatosis.¹ It most commonly is seen in children between the ages of 6 months and 15 years, with the lesions occurring more commonly in girls than in boys.¹ The condition has no significant seasonal variation.^1,2 The etiology is unknown, but studies have shown it to be a T-cell–mediated inflammatory skin disease.²

Lichen striatus is characterized by sudden onset of unilateral linear papules distributed along the lines of Blaschko, usually on the extremities.³ The lesions can progress over the course of days or weeks, and then slowly decrease over a period of 6 to 24 months.³

Three clinical patterns of lichen striatus have been described: typical, which presents with pink, red, or flesh-colored papules; lichen striatus albus, which presents with hypopigmented papules; and nail lichen striatus, which is characterized by thinning, ridging, splitting, and fraying of the lateral portion of a single nail.¹

The differential diagnosis may include linear psoriasis, linear follicular keratosis (linear Darier disease), linear lichen planus, linear porokeratosis, and inflammatory linear verrucous epidermal nevus.³

Treatment of lichen striatus may be limited to active monitoring of the lesion. On average, resolution occurs within 6 months without any medical intervention.¹ If nail involvement is present, resolution can take much longer.

Topical corticosteroids do not appear to shorten the duration of the condition but may help with pruritus if it is present.¹ One recent study has shown that tacrolimus ointment is effective for persistent forms of lichen striatus, with patients showing regression of lesions after 3 weeks of therapy.²

Long-lasting hypopigmentation is common after resolution of lesions, and relapses or recurrent episodes of lichen striatus may occur.³

REFERENCES:

1. Patrizi A, Neri I, Fiorentini C, Bonci A, Ricci G. Lichen striatus: clinical and laboratory features of 115 children. Pediatr Dermatol. 2004;21(3):197-204.

2. Vukićević J, Milobratović D, Vesić S, Milošević-Jovčić N, Ćirić D, Medenica L. Unilateral multiple lichen striatus treated with tacrolimus ointment: a case report. Acta Dermatovenerol Alp Panonica Adriat. 2009;18(1):35-38.

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.