LICHEN STRIATUS - CASE REPORTS

Lichen striatus is an acquired linear inflammatory dermatosis, not frequently reported, with a peculiar clinical aspect, most often described in adults, with a poor response to treatment. We described 4 cases of lichen striatus diagnosed over an 8-month period of time.


Introduction
Lichen striatus is a linear inflammatory dermatitis with unclear etiology.It is a self-limiting eruption characterized by pink, tan or hypopigmented small papules distributed in a linear configuration.The diagnosis is based on clinical picture [1][2][3].In this report we present 4 cases of Lichen striatus with typical lesions, described in 3 adults and one child, with good evolution and clue for etiology.

Case Report Case 1.
A 27-year old woman, presented with a 4-week history of pruritus and erythematous papular eruption localized around the left heel.She was on good health status, not on any systemic medications, with no history of atopy.The clinical differential diagnosis was, at the time of presentation, atypical localization of herpes zoster (serology was negative for varicello-zosterian virus), lichen planus, lupus erythematous and lichen striatus.A skin biopsy was taken and demonstrated a lichenoid chronic inflammation, perivascular lymphocytic infiltrate, the absence of viral inclusions, so the final diagnosis was lichen striatus.The patient was treated with potent topical steroids for three weeks and the lesions almost disappeared, with a slight residual erythema and no other complains (Fig. 1, 2).

Case 2.
A 32 year-old female patient was transferred from Rheumatology Department, where she was hospitalized for a suspicion of Rheumatoid Arthritis, with a sudden appearance of pruritus and erythematous papules, in a linear arrangement, distributed on the inner face of left arm.She was not taken any medication, clinically Lichen striatus was suspected.The patient refused the punch biopsy, it was started treatment with topical steroids class II and the patient was transferred back to the Rheumatology Department for further investigations and treatment for Rheumatoid Arthritis (Fig. 3).

Case 3.
A young boy of 13 years old, diagnosed with atopic eczema at the age of 3, came to us for an opinion, regarding a slight hyper pigmentation, with a linear arrangement along the external face of the right arm.He denied any symptoms, he did not remember the day when he had observed the lesions and he could not tell if they were erythematous at the beginning.No other complains, very good clinical health state, no medication, no allergies, all led us to the suspicion of Lichen striatus late phase.We recommended no medication just emollients) for and in 6 weeks after the initial presentation the hyperpigmentation faded away (Fig. 4).

Case 4.
A 45-year old man, in a good condition, presented with erythematous papular eruption and pruritus on the anterior face of left leg, appeared a few months prior to the presentation.The patient has been seen several times before by different physicians, he had a well established diagnosis of Lichen striatus (confirmed by skin biopsy) and he has tried many different therapeutics schemas, with no improvements: topical steroids for many months, antihistamines orally, antibiotics orally, topical topical application of 0.1% tacrolimus ointment twice daily, topical calcineurin inhibitors; UVB short wave was our therapeutic option, but with no results after 30 seances.We stopped any therapeutically effort and we saw him again in 4 months with the same aspect (Fig. 5).

Discussion
Lichen striatus is an inflammatory, linear dermatitis of unknown origin, rarely reported in our country.It is characterized by small (1 to 5 mm), pink, red, tan, or hypo pigmented papules in a linear configuration or Blaschkoid distribution.The etiology remains obscure, although different theories have been proposed: environmental factors, viral infections, cutaneous injury, hypersensitivity acting on a genetic predisposition [4,5].There is an association between Lichen striatus and atopy which may contribute to its pathogenesis, multiple studies report an increased incidence of lichen striatus in those with atopic family histories (asthma, allergic rhinitis, atopic dermatitis [6].The appearance of lichen striatus that follows the lines of Blaschko suggests a postzygotic somatic mutation [7][8][9].It is more often described in children (especially 5-15 years old), both sexes being equally afflicted, although some studies favor the females [4].

Figure 5. The lesions after UVB treatment (exactly at the beginning of the therapy)
Lichen striatus is a clinical diagnosis; in a doubtful situation skin biopsy is needed o rule out other lichenoid dermatoses (especially lichen planus) [1].In most cases it is a self limiting disease or with a good response to topical treatments [1,10].

Conclusions
We describe 4 cases, with classical aspects and easy diagnosis, occurred on different anatomic sites, different ages of patients, no causes identified, with good response to treatment or self limiting course and one case with no response and long lasting evolution.

Figure 3 .
Figure 3. Lichen striatus on the inner face of left arm of a young woman 24 hours after the appearance Figure 4.A slight hyperpigmentation, with a linear arrangement along the external face of the right arm: possible Lichen striatus