Localized Discoid Lupus Erythematosus of the Ear: The Carpet Tack Sign

A case report published in Cureus has highlighted the diagnostic utility of the carpet tack sign in identifying localized discoid lupus erythematosus (DLE) specifically within the auricular concha of the ear.

Discoid lupus erythematosus is the most frequent form of chronic cutaneous lupus erythematosus (CCLE). It is an autoimmune skin condition that typically presents as persistent scaly plaques.

Understanding Discoid Lupus Erythematosus

DLE is characterized by the appearance of red, inflamed, and coin-shaped patches of skin. These lesions often have a scaly or crusty appearance and are most commonly found on the face, scalp, and ears.

The condition is categorized based on the distribution of the lesions. Localized DLE, which accounts for approximately 80% of cases, refers to lesions located exclusively above the neck.

If the lesions occur on the scalp, they can lead to permanent hair loss. Over time, these areas may progress to atrophy, severe scarring, and dyspigmentation.

On darker skin tones, the center of the lesion often loses pigmentation, while the rim develops a darker color than the surrounding normal skin. On lighter skin, the lesions may appear gray or exhibit minimal color change.

The Carpet Tack Sign and Diagnosis

The carpet tack sign serves as a clinical indicator for DLE. This sign is observed when the adherent white scale is removed from a discoid lesion, revealing horny plugs beneath the surface.

The case report in Cureus emphasizes the relevance of this sign in diagnosing DLE when it occurs in the auricular concha, the central hollow of the external ear.

While clinical signs like the carpet tack sign are useful for identification, a definitive diagnosis of discoid lupus erythematosus is typically confirmed through a biopsy.

Clinical Progression and Treatment

DLE lesions initially present as firm, flat, or raised areas of skin that are dull or purplish red. These areas then develop adherent white scales and may have overlying dried fluid, known as crust.

Without medical intervention, these lesions can persist for several years. The long-term impact often includes extensive scarring and changes in skin pigmentation.

Treatment typically begins with a combination of sunscreen and topical steroids. In cases where these initial treatments are ineffective, physicians may prescribe oral medications, most commonly hydroxychloroquine or related drugs.

Relationship with Systemic Lupus

There is a documented relationship between cutaneous and systemic forms of the disease. Patients with systemic lupus erythematosus (SLE) frequently develop discoid lupus lesions.

However, the reverse is less common; patients who initially present with discoid lupus infrequently go on to develop systemic lupus.

Research indicates that DLE is significantly more prevalent than SLE, estimated to be two to three times more common.

• Localized DLE: Lesions limited to the area above the neck.
• Generalized DLE: Lesions appearing both above and below the neck.
• Childhood DLE: A specific classification for the condition occurring in children.