Lichen planus is an acquired inflammatory disease of the skin, mucous membranes and nails. It is characterized by pruritic polygonal livid papules. The disease was first described by Erasmus Wilson in 1869. It is primarily a disease of adults, and it usually occurs between the ages of 30 and 60, without gender predominance. The exact incidence and prevalence of this disease are unknown, but it is thought to affect less than 1% of the general population (0.14 to 0.80%) (1).
A 63-year old male patient was admitted to our Department with itchy erythematous papules and plaques which appeared a month before admission. On admission, numerous erythematous and livid papules and plaques of polygonal shape up to 5 mm in diameter were present in the lines of Blaschko, along the left lower extremity, left side of the trunk and the left upper arm (Figures 1-3), while mucous membranes, nails and scalp were spared.
Blaschko-linear distribution of skin lesions was first described by a German dermatologist Alfred Blaschko in 1901 in his work ”The distribution of nerves in the skin and their relationship to diseases of the skin”. In 1978, Happle first published that genetic mosaicism was the cause of these peculiar skin changes (1,4,6). Although knowledge of mosaicism in the skin was further elucidated in articles of several authors (Taieb in 1994, Bolognia in 1994, Heide 1996), the exact mechanism and molecular basis for the development of Blashcko linear distribution has not been fully clarified yet (5). Blaschko lines may be related to X-linked, congenital and inflammatory dermatoses, and they may be found in several skin conditions like segmental forms of atopic dermatitis, erythema multiforme, pemphigus vulgaris, vitiligo, and granuloma annulare. This is a case report of a patient with a rare form of lichen planus, with typical clinical manifestations and with Blaschko-linear distribution. Lichen planus in the lines of Blaschko was also described in several other dermatoses: lichen striatus, lichen sclerosus, morphea, porokeratosis of Mibelli, mucinosis follicularis and psoriasis vulgaris. The treatment included topical corticosteroids under occlusion, due to comorbidities, with satisfactory response. Other options include, topical calcineurin inhibitors, intralesional and systemic corticosteroids, retinoids, phototherapy and in resistant cases that severely affect the quality of life methotrexate, cyclosporine and thalidomide.
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