Derm Dx: White streak on the leg - Clinical Advisor

Derm Dx: White streak on the leg

Slideshow

  • Lichen Striatus 1_0812 Derm Dx

  • Lichen Striatus 2_0812 Derm Dx

A mother brings her 4-year-old daughter to the dermatology clinic for her first consultation for a white streak on the leg, which was not present at birth. Twelve months prior, the patient developed very fine pink papules in a linear distribution along the leg and thigh, the mother reports. Subsequently, the papules disappeared leaving only a hypopigmented streak.

The patient denies any associated itch or pain, is otherwise health and takes no medications. Her father has type 2 diabetes. All of her siblings are healthy. What’s your diagnosis?

Submit your answer, and then read the full explanation below. If you like this activity or have a suggestion, tell us about it in the comment box at the bottom of the page.

Lichen striatus is a relatively common, self-limited and benign eruption that occurs most commonly in children. It occurs in females two to three times more frequently than males.Lichen striatus eruptions begin as small, skin-colored or pink papules that may coalesce. ...

Submit your diagnosis to see full explanation.

Lichen striatus is a relatively common, self-limited and benign eruption that occurs most commonly in children. It occurs in females two to three times more frequently than males.

Lichen striatus eruptions begin as small, skin-colored or pink papules that may coalesce.  The papules form a linear, albeit often discontinuous, streak. The distribution is believed to follow the lines of Blaschko, which represent pathways of epidermal cell migration during fetal development. Incontinentia pigmenti is another example of an eruption in a Blaschkoid distribution.

Lichen striatus typically affects the extremities and trunk, with the leg being the most commonly involved area.When the nail is involved, there may be nail plate grooving, splitting, or ridging.

The active, papular lesions of lichen striatus last an average of one to two years, after which the lesions flatten and leave a hypopigmented streak. Hypopigmentation tends to persist for several years and then resolve. All stages of the eruption are generally asymptomatic; however, pruritis may occur, especially if there is a history of underlying eczema.

Lichen straitus rarely occurs in adults, but when it has, it has been termed “blaschkitis.” It most likely represents an identical entity to childhood lichen striatus.

The etiology of lichen striatus remains a mystery. Eruptions clustered in families have been reported, and a viral etiology has been suggested. However, no virus has been identified, and there are no extracutaneous manifestations of the disease, nor is it accompanied by prodromal symptoms.

The histological features of lichen striatus are lichenoid, which means that there is a band-like infiltrate of lymphocytes at the dermal-epidermal junction. The infiltrate extends deeply and surrounds sweat glands and ducts, which is not a feature of lichen planus.

Diagnosis

The diagnosis is usually straightforward when there is a sudden eruption of subtle papules in a Blaschkoid distribution. Patients frequently present during the hypopigmented phase of the eruption. In these cases the diagnosis is clinched by the presence of the hypopigmented streak in a Blaschkoid distribution. Biopsy is rarely required but may be useful, if the diagnosis is in doubt.

Lichen planus is most commonly characterized by an eruption of very pruritic polygonal flat-topped purplish papules which resolve with hyperpigmentation.

Vitiligo presents with skin depigmentation, not hypopigmentation.  There is no initial papular component in vitiligo.  Additionally, it would be rare for vitiligo to present in a Blaschkoid distribution.

Lichen spinulosa is an eruption of clusters of spiny keratotic papules resembling keratosis pilaris.

Lichen nitidus is an eruption of small, shiny, flat-topped asymptomatic papules, most commonly on the dorsal hands, forearms and penis.  It does not present in a Blaschkoid distribution.

Treatment and prognosis

Lichen striatus is self-limited, usually asymptomatic, and no treatment is required. Topical corticosteroids may be of some benefit if pruritis is present.

Adam Rees, MD, is a graduate of the University of California Los Angeles School of Medicine and a resident in the Department of Dermatology at Baylor College of Medicine in Houston.

References

1. Bolognia J, Jorizzo JL and Rapini RP. ” Chapter 12: Lichen Planus and Lichenoid Dermatoses.” Dermatology. St. Louis, Mo.: Mosby/Elsevier, 2008.

2. James WD, Berger TG, Elston DM et al. “Chapter 12: Lichen Planus and Related Conditions.” Andrews’ Diseases of the Skin: Clinical Dermatology. Philadelphia: Saunders Elsevier, 2006.

3. Schachner LA, Hansen RC. “Chapter 14: Eczematous dermatitis.” Pediatric Dermatology. Edinburgh: Mosby/Elsevier, 2010.

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