Unilateral Discoid Lupus Erythematosus Over the Face: An Unusual Presentation.

Sir,

Discoid lupus erythematosus (DLE) is the most common form of chronic cutaneous LE (CCLE). It usually presents as single or multiple erythematous scaly plaques which later develop atrophy, scarring, and hypo and/or hyperpigmentation. Photo-distributed areas such as the face, scalp, ears, and extensor aspect of upper limbs are commonly involved. Strictly unilateral but multifocal distribution of discoid rash over the face is very unusual.

A 13-year-old girl presented with erythematous rash involving the right side of her face for the last 6 months. She had mild photosensitivity and occasional itching on the plaques. On clinical examination, there were multiple plaques present over the forehead, lateral wall of nose, cheek, and chin [Figure 1a and b]. Careful examination of plaques over the forehead, philtrum of lip, and chin suggested that the lesions were strictly demarcated to the right side of the face with a sharp cut off in the midline. The plaques had minimal induration in the centre with prominent follicular plugging in few of the lesions [Figure 1b, inset]. There was no scaling, atrophy, scarring, or pigmentry alteration in the lesions. Other parts of the body and mucosa were not involved. There were no joint pains or any other systemic complaints. There was no history suggestive of sunlight exposure to the right side of the face selectively while traveling. We considered differential diagnosis of DLE, polymorphous light eruption, and pseudolymphoma. Histopathological examination of skin biopsy showed focal epidermal atrophy with basal cell degeneration [Figure 2a]. Hair follicles showed keratotic plugging and marked damage to basal cells of follicular epithelium along with infiltration of lymphocytes and histiocytes extending up to lower dermis. Special staining with PAS revealed deposition of mucin in the dermis [Figure 2b]. Her anti-nuclear antibody titer (IF microscopy on Hep 2 cells) was negative and other routine investigations including hemogram, urine microscopy, liver and renal function test were normal. A diagnosis of DLE was made based on morphology of lesions and typical histopathological findings. She was prescribed oral hydroxychloroquine 200 mg daily along with mid potency topical corticosteroids and sun protective measures. With this treatment she had around 80–90% improvement in the form of decreased infiltration and erythema over the next 4 months.

Figure 1

(a) Front view of the face showing multiple erythematous plaques over the right side of the face (cheek, chin, and forehead). (b) Lateral view of the face showing erythematous plaques with mild central scaling. Inset, close view of the prominent follicular plugging

Figure 2

(a) HPE, ×20 showing focal epidermal atrophy with basal cell degeneration; hair follicles showed keratotic plugging and marked damage to basal cells of follicular epithelium which were surrounded by infiltration of lymphocytes and histiocytes. (b) PAS staining showing mucin deposition in dermis

In a majority of the CCLE patients, lesions are multiple and present bilaterally. However, sometimes CCLE can have very atypical presentations which makes the diagnosis difficult leading to delayed diagnosis and adverse sequel.[12345] Unilateral involvement in CCLE has been reported in the form of either single focal persistent plaques over eyelids[125] or single linear long erythematous plaque extending along the length of the limb[3] or as multiple lupus profundus lesions arranged in a single linear distribution commonly along the blashko line.[4] These cases of focal or linear DLE are rare and long-term follow-up is lacking. Therefore, it is difficult to comment whether there is any difference in their prognosis compared to the usual DLE cases.

Our case is unusual as the patient had multiple lesions over the face which were strictly localized to the right side but were not appearing to be present in an exactly linear fashion. One of the plausible explanations which can be forwarded is selective photoexposure to one side of the face. However, detailed history and probing for such exposure did not reveal anything significant. Moreover, the midline cut-off of the lesions over the forehead and chin cannot be accounted for by selective photoexposure. We propose that in this case the lesions were present along multiple closely placed curvilinear blashko lines over the face because of which a clear linear distribution could not be appreciated.

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