Dermatology Online Journal

Widespread Blaschkoid lichen planus
Heather A Klein MD, Richard A Krathen MD, Sylvia Hsu MD
Dermatology Online Journal 12 (7): 17

Department of Dermatology, Baylor College of Medicine, Houston, Texas

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Many clinical variants of lichen planus exist, and case reports of linear lichen planus and of lichen planus in a unilateral distribution have been reported in the literature. We report a striking case of unilateral linear lichen planus following Blaschko lines on the trunk and extremities.

Clinical synopsis

Figure 1	Figure 2
Figure 1. Violaceous macules on the right side of the chest extending down the right arm
Figure 2. Violaceous macules on the right back.

Figure 3
Violaceous macules extending down the right posterior leg

A 31-year-old healthy woman presented with a 2-year history of an itchy rash on the right side of her body. She had no medical illnesses and took no medications. She had received no prior treatment. Physical examination revealed hyperpigmented macules, pink-to-violaceous macules, and slightly scaly papules in a linear distribution over the right chest (Fig. 1), right back (Fig. 2), right arm, palm, flank, and leg (Fig. 3) with a sharp demarcation at the midline. The lesions were noted to follow Blaschko lines on the skin. No oral lesions were present. Hepatitis serology was negative. Punch biopsy showed an interface lichenoid dermatitis with features characteristic of lichen planus. This patient was given a 3-week course of prednisone 40 mg daily with clinical and symptomatic improvement, at which time the patient was tapered off prednisone over the next few weeks.

Comment

Lichen planus is a cutaneous and mucous-membrane disorder of unknown etiology characterized by pruritic, planar, polygonal, purple papules that upon close examination have a white lacy reticular surface. Several variants have been described, including linear lichen planus sometimes following Blaschko lines. Blaschko lines, distinct from Voight lines, Langer lines, and the lines of innervation of the spinal nerves, follow a V-shape on the back, an S-shape on the abdomen, an inverted U-shape on the upper chest, and a linear pattern down the front and back of the lower extremities [1]. Long et al. reported linear lichen planus following Blaschko lines, as in our patient [2]. This patient's lesions were not confined to one side of the body, but rather began on the right side of the chest and spread to the trunk, arms, left thigh, left foot, and third finger of both hands.

Unilateral lichen planus is also described. Saxena et al. report a 26-year-old healthy woman with lichen planus distributed over only the left side of her body below the neck [3].

Some cases of linear lichen planus presenting in a unilateral distribution have been reported in patients with precipitating factors. Krasowska et al. reported a case of a healthy 33-year-old woman with lichen planus in a linear distribution following Blaschko lines limited to the right side of the body occurring after three successive deliveries of healthy babies [4]. Her hepatitis B and C serologies were negative, and she had no nail or mucosal involvement. Jury et al. reported a case of linear lichen planus confined to the right lower extremity in a 36-year-old man with a 3-year history of hepatitis C [5]. In addition, Gupta et al. reported a case of linear lichen planus confined to the left side of the body of a 61-year-old man; this was thought to result from the Koebner phenomenon secondary to the nitroglycerin patches the patient used in the involved areas [6].

Hartl et al. reported a prior case of unilateral linear lichen planus in a 33-year-old healthy hepatitis-C negative woman who had a linear eruption of lichen planus isolated to the left side of her neck that eventually involved the left side of her tongue and her left buccal mucosa [7].

The differential diagnosis of Blaschkoid LP includes lichen striatus, epidermal nevus, and linear psoriasis. Our case demonstrates an uncommon presentation of lichen planus that was both linear and unilateral in a healthy woman with no known precipitating factors. The pattern seen in the figures demonstrates the unusual pattern of lichen planus in this patient that resembles that seen in other mosaic dermatoses.

References

1. Jackson R. The lines of Blaschko: a review and reconsideration: observations of the cause of certain unusual linear conditions of the skin. Brit J Dermatol 1976; 95: 349-360.

2. Long CC, Finlay AY. Multiple linear lichen planus in the line of Blaschko. Brit J Dermatol 1996: 135: 275-6.

3. Saxena AK, Nigam PK. Unilateral lichen planus. Cutis 1988; 42: 142-3.

4. Krasowska D, Pietrzak A, Lecewicz-Torun B. Unilateral multiple linear lichen planus following the Blaschko lines recurring after deliveries. Dermatol 2001; 202: 340.

5. Jury CS, Munro CS. Linear lichen planus related to hepatitis C infection? Brit J Dermatol 2000; 142(4): 836-7.

6. Gupta AK, Gorsulowsky DC. Unilateral lichen planus: an unusual presentation. Arch Dermatol 1987; 123: 295-6.

7. Hartl C, Steen KH, Wegner H, Seifert H, Bieber T. Unilateral linear lichen planus with mucous membrane involvement. Acta Dermato-Venereol 1999; 79: 145-6.

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