Lichen sclerosus (LS) is a chronic inflammatory disease of uncertain etiology affecting skin and mucosal surfaces. Majority of the cases (around 85%) involve the genital area while extragenital cases are encountered less frequently (15–20%). Genital LS can occur simultaneously with extragenital LS; however, only in 6% of the cases, the extragenital type has been described to occur in isolation [1, 2]. Classically, extragenital LS affects sites which include neck, upper trunk, and shoulders [3]. Only a handful of cases of extragenital LS following lines of Blaschko (LB) have been described in the literature [2]. In this article, the author reports a case of extragenital LS in a Blaschkoid pattern, an exceedingly rare presentation. Additionally, a tabulated review of the published cases of Blaschkoid LS has been presented and dermoscopic findings and treatment of extragenital LS have been discussed.
A 40-year-old male presented with multiple asymptomatic whitish papules on his chest in a U-shaped distribution which he noticed 3 months ago. Initially, the lesions appeared on the right side of the chest and progressed further crossing the midline to involve the left side of the chest as well. He denied any past or family history of similar looking lesions. On examination, there were multiple small discrete rounded depigmented atrophic macules and papules of variable size (1–3 mm in diameter) which were present in a U-shaped pattern along the lines of Blaschko on both sides of the chest (figs. 1 A–C). Dermatologigal examination did not reveal any changes of hair, nails, oral and genital mucosae. Systemic examination was non-contributory. KOH wet mount did not reveal any fungal elements. Routine laboratory tests including ANA and Borrelia serology were unremarkable.
Dermoscopy showed white structureless areas with telangiectasia (figs. 2 A, B). Punch skin biopsy showed epidermis with compact ortho-hyperkeratosis with follicular plugging. Stratum Malpighi was atrophic with effacement of rete ridges. Upper dermis showed sclerosis and homogenization of collagen with diffuse lymphocytic infiltrate. Dilated capillaries with mild perivascular lymphocytic infiltrate were present in the mid dermis (fig. 3). Clinical, dermoscopic and histopathological correlation was consistent with Blaschkoid extragenital LS. The patient was prescribed topical tacrolimus 0.1% ointment to be applied twice daily and is still under follow up.
Lines of Blaschko (LB) are imaginary lines that represent the boundaries between normal and mutant skin due to mosaicism. Several dermatoses have been reported to follow LB like lichen planus, psoriasis, lichenoid drug eruption, lichen striatus, morphea, lupus erythematosus, etc. [4, 5]. However, extragenital LS in a Blaschkoid pattern, has rarely been reported.
Izumi and Tajima described the first case report of a linear LS in 1995 [6]. Since then, less than a dozen cases of linear LS have been described. Kim and Lee have reviewed 6 cases of Blaschkoid LS involving the trunk, limbs or face [7]. Despite meticulous medical literature review, the author could find only 11 cases (table 1) of Blaschkoid LS reported to date [2, 3, 5–9]. The present case is the 12th case in this series.
Extragenital LS usually affects upper trunk and proximal limbs. It clinically presents as asymptomatic to mildly pruritic rounded whitish papules with some atrophy, usually appearing over the upper back, chest, abdomen and neck. These lesions may coalesce with one another to form well-demarcated plaques studded with comedo-like plugs which in due course of time turn atrophic and appear as ivory-white patches. Such patches show a tendency for scar formation [1, 8]. However, in the present case, the lesions remained discrete and followed the LB in a U-shaped configuration.
Recently, researchers have described some consistent dermoscopic patterns in the lesions of LS which can aid in its diagnosis and may avert the need of skin biopsy. Whitish structureless areas (WSA), white chrysalis like structures (WCLA), telangiectasia of different lengths and calibers, perifollicular scales, keratotic plugs, erythematous areas, rosettes, comedo-like openings (CLO) and peppering are the dermoscopic findings reported in extragenital LS [1, 10]. These dermoscopic findings correspond to certain histopathological features. WSA correspond to atrophic epidermis and dense hyalinization of the upper dermis; WCLA are due to increased collagen deposition, CLO correspond to dells suggestive of appendageal ostia; while telangiectasia and dotted vessels are due to inflammation viewed through an atrophic epidermis. Scaling corresponds to hyperkeratosis; the peppering blue gray dots correspond to dermal melanophages and pigment incontinence due to vacuolar interface [1, 10].
The treatment of extragenital LS has been reviewed. Ultra-potent topical corticosteroids have been proposed as the first-line of treatment. However, for treating extragenital LS, they are not as efficacious as they are in the case of genital LS [1, 11]. Topical immunomodulators such as calcineurin inhibitors (tacrolimus and pimecrolimus), retinoids, vitamin-D analogues and PUVA are the other possible treatment options which have been tried with lower efficacy than that of topical corticosteroids [1, 11, 12]. Other treatment modalities for extragenital LS include phototherapy (low-dose ultraviolet-A1, oral PUVA, NB-UVB), surgical excision, carbon dioxide laser, platelet-rich plasma, adipose-derived stem cells and pulse dye laser [1, 11–13]. For generalized or treatment resistant LS, systemic treatment may be required. Oral corticosteroids, cyclosporine, methotrexate, hydroxyurea, retinoids, penicillin G, ceftriaxone, sulphasalazine, and vitamin A/D/E single or in combination have been tried. Due to the paucity of clinical trials, evidence for systemic treatment in LS is lacking [1, 13–15].
Since extragenital LS is a rarely reported entity, the Blaschkoid configuration of the lesions further adds rarity to this case, hence obliged to report it.
FUNDING
No external funding.
ETHICAL APPROVAL
Not applicable.
CONFLICT OF INTEREST
The author declares no conflict of interest.
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