An Unusual Case of Linear Cutaneous Lupus Erythematosus.

Sir,

Linear cutaneous lupus erythematosus is an uncommon variant of lupus erythematosus (LE) presenting along the lines of Blaschko. Herein, we report a case of linear cutaneous lupus erythematosus, highlighting the necessity of biopsy to rule out clinical differentials in patients presenting with a linear arrangement of lesions on the face.

A 32-year-old lady presented with an asymptomatic, linear pigmented lesion on the forehead and left side of nose, of 2 months duration. The lesion started on the forehead and progressed caudally to attain the present status. There were no other symptoms including photosensitivity. Cutaneous examination revealed a linear hyperpigmented plaque extending from the left side of forehead to left ala nasi [Figure 1]. Upper part of the lesion (on forehead) was mildly atrophic and non-scaly. However, lower part of the lesion (over the nose) was slightly elevated and scaly. Rest of the mucocutaneous examination was unremarkable. Linear lichen planus and lichen planus pigmentosus were considered as differentials and a punch biopsy from the active part of the lesion over the nose was done. Histopathology showed prominent follicular plugging, lymphohistiocytic infiltration [Figure 2a], and basal layer degeneration [Figure 2b]. The inflammation extended to interfollicular epidermis, causing focal basal layer vacuolar degeneration, pigment incontinence, and cytoid bodies. Histopathological findings were consistent with cutaneous lupus erythematosus. Linear lichen planus and linear lichen planus pigmentosus were ruled out, on the basis of prominent follicular plugging, periappendageal infiltration, and absence of hypergranulosis. Thus, on clinicopathological correlation, a diagnosis of linear cutaneous lupus erythematosus was made. Routine laboratory investigations including serum biochemistry panel were within normal limits. Antinuclear antibody (ANA) by immunofluorescence was weakly positive. Direct immunofluorescnce (DIF) from the lesion could not be done. The lady was treated with tacrolimus 0.1% ointment but was lost to follow up.

Figure 1

Linear, pigmented plaque extending from the forehead to left ala nasi. The upper part of the lesion is non-scaly and slightly atrophic. The nasal part of the lesion is slightly thickened and scaly

Figure 2

(a) Follicular plugging, periappendageal infiltration (H and E ×40). (b) Lymphohistiocytic infiltration and basal layer vacuolar degeneration (H and E ×400)

Cutaneous lupus erythematosus can present in varied morphologies and distribution patterns, linear being one of the rarest patterns. Linear discoid lupus erythematosus was first reported by Abe et al. in 1998.[1] It is mostly seen in children and young adults, without any gender predilection. Linear cutaneous lupus erythematosus may present with pigmented plaques, atrophic lesions, or verrucous plaques.[23456] Such lesions have been reported to develop on the forehead, cheeks, nose, neck, chest, back, and upper extremities.[2345678] Photosensitivity and ANA are negative or weakly positive. Progression to systemic lupus erythematosus has not been reported, but as the condition is relatively new and little is known about the long-term prognosis, regular monitoring of the patient is required.[8]

The condition must be differentiated from clinical mimickers like linear lichen planus, lichen striatus, linear psoriasis, inflammatory linear verrucous epidermal nevus and linear morphea. Treatment options include topical anti-inflammatory agents like corticosteroids and calcineurin inhibitors; oral steroids, hydroxychloroquine, and other steroid-sparing immunosuppressives.[9]

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Conflicts of interest

There are no conflicts of interest.