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Unilateral Blaschkoid lichen planus involving the entire half of the body, a unique presentation

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Unilateral Blaschkoid lichen planus involving the entire half of the body, a unique presentation
Simeen Ber Rahman1, Arfan Ul Bari2, Nadeem Mumtaz1
Dermatology Online Journal 13 (3): 36

1. Department of Dermatology, Military Hospital, Rawalpindi, Pakistan


A large number of congenital as well as acquired skin disorders assume a characteristic morphological pattern following the Blaschko lines. Lichen planus (LP) is an acquired inflammatory disorder that can come with different faces. Linear lesions are frequently seen but cases of zonal (zosteriform) or whorled appearance have rarely been described in the literature. We describe an even rarer presentation in a 30-years-old man who had unilateral pruritic violaceous lesions over right half of body characteristically following lines of Blaschko with clinical and histological morphology typical of LP.

Blaschko lines constitute a surface pattern that is distinguished from other morphological lines, such as Voight's lines, Langer's lines and skin dermatomes [1]. Blaschko lines are V-shaped on the upper spine, S-shaped on the abdomen, inverted U-shaped from the breast area to the upper arm, and perpendicular down the front and back of the lower extremities (where it was first described by a German dermatologist, Alfred Blaschko in 1901 [2]. These lines were thought to represent a clinical expression of a genetically programmed clone of altered cells, perhaps first expressed during embryogenesis. They never cross the anterior truncal midline, but run along it. Authentic genetic mosaicism has been proven only in cases of Blaschko-linear nevoid or X-linked diseases and it is still less obvious in acquired inflammatory diseases [3, 4].

Lichen planus (LP) is one of common acquired dermatoses that most commonly presents as pruritic, papular eruption characterized by its violaceous color, polygonal shape, and sometimes fine scale found on the flexor surfaces of upper extremities, genitalia and mucous membranes. Lichen planus is thought to be an immunologically mediated disorder. There may be a genetic susceptibility to idiopathic LP. However genetic heterogenecity in LP has led to a suggestion that idiopathic LP may have a different pathogenesis [5, 6]. Sometimes it is also associated with hepatitis-C infection, chronic active hepatitis, and primary biliary cirrhosis [7]. In addition to the cutaneous eruption, lichen planus can involve the mucous membranes, genitalia, nails, and scalp. The clinical presentation of the disease has several forms, including actinic, annular, atrophic, erosive, follicular, guttate, hypertrophic, linear, and vesicular [5, 6, 7]. In lichen planus linear lesions are frequently seen but cases of zonal or zosteriform LP have been described in the literature [8]. The exact cause of this blaschkoid pattern of the disease has not yet been ascertained but it is considered as blaschkitis (an acquired inflammation along blaschko lines) without koebnerization or a result of wolf's isotopic response (koebner phenomenon) [8, 9]. The aim of presenting this case is to highlight this fascinating pattern that can involve a line , a band, a segment or whole of one half of the body.

Clinical synopsis:

A 30-year-old man presented with history of linear pruritic lesions over right half of the body that appeared 8 months previously. On physical examination violaceous brown polygonal 1-5 mm papules, coalescing at places in whorls and linear shapes following lines of Blaschko, were observed over right half of the body (Fig. 1). The patient had moderate itching. There was no history of any drug intake prior to eruption and no involvement of or nails. The mucous membranes, scalp and nails were not affected. The patient had history of polio affecting the right upper limb in childhood. On systemic examination, no abnormality was found. The results of laboratory examination including complete blood cell count, liver functions, and urinalysis were within normal limits. Serologies for hepatitis B and C viruses were negative. Histologic examination of one of the sites revealed a lichenoid band-like lymphohistiocytic infiltrate at dermoepidermal junction, dyskeratotic keratinocytes, and wedge-shaped hypergranulosis and orthokeratosis consistent with LP. There were decreased epidermal melanocytes and pigmentary incontinence with dermal melanophages. Another biopsied lesion from a relatively flattened lesion, showed sparse infiltrate with melanophages around papillary blood vessels which were dilated mildly and surrounding fibrosis. He was treated with topical steroids and antihistamines. His itching improved but lesions persisted with 1 month treatment. A regular follow-up was suggested to see the course of the disease.

Figure 1Figure 2
Figure 1. Violaceous brown linear and whorled lesions restricting only to right half of the body
Figure 2. Lines over arm and whorls over trunk strictly following lines of Blaschko.

Figure 3Figure 4
Figure 3. Close up of linear blaschkoid pattern over lower extremity
Figure 4. Histopathology showing classic changes of lichen planus (basal cell degeneration, pigmentary incontinence and band like cellular infiltrate at dermoepidermal junction). Original magnification X 40.


Lines of Blaschko are thought to result from a form of human mosaicism in which different groups of cells behave differently for reasons that are not yet clear. Almost all epidermal nevi follow the pattern of lines of Blaschko [3, 4]. Lichen planus following the lines of Blaschko has so far been considered, either a blaschkitis without koebnerization or a result of Wolf's isotopic response (koebner phenomenon) [8, 9]. Most cases of linear as well as zosteriform distribution of LP, previously described in literature were satisfactorily explained on the basis of Koebner phenomenon as they appeared either secondary to some trauma or in the healed lesions of some pre-existing disease like herpes zoster. The majority of the cases occurred either on trunk or extremities in a form of localized segmental distribution [6, 8, 9]. In recent past, blaschkitis. (idiopathic dermatitis along lines of Blaschko) has been regarded as the cause of some cases of LP following Blaschko lines. This new entity of idiopathic acquired inflammation may well explain the cases in which there is no underlying isomorphism. The exact cause of this relatively new entity was not known but it could be the result of some new food, drug, or some infective agent [8, 9, 10]. In a recent study of nine such cases from Pakistan [10], six revealed classic histological changes of lichen planus, two had lichenoid drug reaction and one was suggestive of lichen planus pigmentosis. In our case the histology revealed changes of LP but the distribution, in the absence of isotopic response, suggested this to be another case of blaschkitis with extensive body involvement. To the best of our knowledge, such case with unilateral involvement of LP following lines of Blaschko on almost entire half of the body, has not been reported, except for one report from India where unilateral multiple linear LP lesions were reported on chest and abdomen [11]. Although association of LP with viruses as Hepatitis C virus has been well established [7] but LP and Polio in our case looked merely coincidental.


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