The lines of Blaschko represent the developmental growth pattern during epidermal cell migration. They are a pattern followed by many skin disorders. Multiple clinical variants of lichen planus have been reported, but lichen planus following the Blaschko lines is extremely rare.

We present a rare case of linear lichen planus, which follows lines of blaschko.

A 43-year-old woman presented with an itching rash of 4 months duration. She had no personnel medication history and no family history of similar skin lesions.

Examination revealed linear unilateral poorly delineated purple papular and violaceus plaques along Blaschko’s lines on the lower right limb (Fig. 1). No other manifestations were noted.

Figure 1: A linear unilateral poorly delineated purple papular and brownish plaques along Blaschko’s lines on the lower right limb.

Different diagnoses were considered such as drug reaction, linear Lichen planus pigmentosus (LPP), linear lichen planus (LP), and postinflammatory hyperpigmentation.

Routine laboratory findings did not show any abnormalities. Serological tests for hepatitis B and C virus infection were negative. A skin biopsy showed hyperkeratosis, acanthosis, an accentuated granular layer and a band-like lymphocytic infiltrate along the dermal-epidermal junction.

Unilateral Blaschko-linear LP was diagnosed.

Linear LP is a rare LP characterized by lichenoid, pruritic, violaceous papules with a smooth surface, arranging in a linear pattern [1]. Linear LP is frequently observed in childhood and the adolescent period.

The differential diagnosis of the linear variant of LP includes lichen striatus, linear psoriasis, inflammatory linear verrucous epidermal nevus, drug reaction and linear Darier disease [2].

The diagnosis is based on clinical manifestations and histopathological findings [3].

In conclusing, Blaschkoid LP is usually benign and selflimiting. Dermatologists must be aware of this condition, so the diagnosis can be made at an early stage, improving the patient’s quality of life.

REFERENCES