Unilateral zosteriform lichen planus involving multiple noncontiguous dermatomes with oral involvement.

Sir,

A 20-year-old female presented to us with lesions over right side of her body with mild itching and pigmentation in oral cavity since 1 month. The lesions started from right hand which, progressed to involve lateral forearm, and arm upto the scapula. The lesions later involved inframammary region, lower abdomen, and posterolateral aspect of thigh on the same side followed by asymptomatic involvement of bilateral buccal mucosa. There was no history of trauma, dental procedure, infection, drug intake or prior dermatological diseases, such as herpes zoster. There was no family history of identical skin disease.

On examination, multiple erythematous to hyperpigmented papules were present over the lateral aspect of the right upper limb upto the scapular region along C7,8 (cervical) dermatome with koebnerization [Figure 1a and b]. Multiple grouped papules of similar morphology forming a band over right inframammary region involving T5,6 (thoracic), right lower abdomen at T12, and right posterolateral thigh at S1 (sacral) dermatomes was seen [Figure 2a–c]. Single hyperpigmented papule over right lower lip with hyperpigmented patches in lacy pattern over bilateral buccal mucosa were noted [Figure 3a and b]. Nails, scalp, and genitals were normal. Systemic examination was unremarkable. Lichen planus (LP) and lichen striatus were kept as differentials and biopsy was taken, which showed focal mild acanthosis and hypergranulosis in the epidermis with band-like infiltrate of lymphocytes in the upper dermis leading to disruption of the dermoepidermal junction and pigment incontinence [Figure 4]. A mild perivascular and periappendageal lymphocytic infiltrate with exocytosis of lymphocytes at few places was present. These features were suggestive of LP. The patient was given topical steroids for skin lesions and buccal mucosa. Lesions were not progressive but no improvement was seen in pigmentation after a month of follow-up.

Figure 1

Multiple erythematous to hyperpigmented papules over (a) lateral aspect of the right upper limb; (b) right scapular region along C7,8 distribution with koebnerization

Figure 2

Multiple erythematous to hyperpigmented papules over (a) right inframammary region involving T5,6 dermatome, forming a band; (b) right lower abdomen at T12; (c) right posterolateral thigh at S1 dermatomes

Figure 3

(a) Single hyperpigmented papule over right lower lip; (b) hyperpigmented patches in lacy pattern over buccal mucosa

Figure 4

Mild acanthosis and hypergranulosis in the epidermis with band-like infiltrate of lymphocytes in the upper dermis leading to disruption of the dermoepidermal junction and pigment incontinence. (Hematoxylin and eosin stain, ×4 magnification)

LP is an inflammatory mucocutaneous disease in which cell-mediated immunity plays a major role in triggering the disease. Typical cutaneous LP presents as extremely pruritic, polygonal, flat-topped, violaceous papules, and plaques.[1] Oral mucosa is commonly involved in LP, mostly as asymptomatic whitish and reticular patches. Many clinical variations of LP have been described according to the configuration and morphologic appearance, of which linear and zosteriform LP are rare. Zosteriform pattern is a variant of LP that may occur without evidence of herpes zoster.[2] It usually involves one or two continuous dermatomes.

Zosteriform and blaschkoid forms arise either as Koebner's phenomena, Wolf's isotopic phenomena, or de novo from normal skin.[2] It differs from the usual LP by absence of oral cavity involvement and severe itching,[2] which contradicts our case of unilateral LP presenting with multiple discrete lichenoid papules along dermatomal distribution with mild itching and oral changes with no prior history of herpes zoster or trauma to her skin.

Distribution of lesions in linear/zosteriform LP suggest a theory of neural origin while recently it has been suggested that most of the lesions occurring in so-called zosteriform manner do not follow a dermatomal pattern or apparently a nerve segment but are rather along the Blaschko's lines.[3] Some authors believe that true zosteriform LP only exists in cases of isotopic phenomena on the sites of healed herpes zoster.[4]

Most of the cases of zosteriform LP reported as per our literature search [Table 1], were males,[3567891011121314] aged between 30 and 40 years,[56789] mainly involving left side of the body,[357910111516] where as our case was a 20-year-old female with involvement over right side of the body. Only two patients had prior history of herpes zoster[1216] and one patient had history of extracorporeal shock wave lithotripsy.[15] All other cases did not have previous history of herpes zoster similar to our case. In addition to lesions of LP over body our patient had mucosal involvement, which was seen in three other cases, one with oral involvement[8] like ours and other two had genital involvement.[610] Only one case had multiple non-contiguous involvement[14] as in our case, whereas in all other cases, there was involvement of one or two dermatomes.

Table 1

Reported cases of zosteriform lichen planus

There is a definite distinction between the linear and zosteriform type of LP. In the former, the papules appear as narrow lines about 1 or 2 cm wide, which may follow the course of a nerve, vein, lymphatic vessel or of Voigt lines, whereas in zosteriform a band (several centimeters wide) follows the course of a peripheral cutaneous nerve and its branches or appears over areas of radicular nerve distribution as in our case. The zosteriform arrangement of lichenoid papules is rare and is interpreted as a cutaneous reaction possibly triggered by some neural factor.[17]

The histology of LP is characteristic and enables distinction from other linear dermatoses such as lichen striatus, linear nevi, and linear psoriasis. Treatment modalities include topical moderate- to high-potency corticosteroids, topical salicylic acid, and systemic antihistamines. In unresponsive cases systemic corticosteroids or intralesional corticosteroids can be instituted.

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