Diagnosis: Discoid lupus erythematosus (DLE)
Systemic lupus erythematosus (SLE) was originally defined by the American College of Rheumatology (ACR), formerly the American Rheumatism Association, in 1971. This classification was revised in 1982 to include many of the serologic tests used to diagnose and manage SLE. In 1997, the ACR again updated the criterion of this immunologic disorder.1,2
Patients must meet four of the 11 criteria during any time interval to be diagnosed with SLE.1,2 ACR criteria include four mucocutaneous manifestations: malar rash, discoid rash, photosensitivity, and oral ulcers. Using the ACR classification, the diagnosis of SLE can be made on these mucocutaneous manifestations alone.2,3
The 2012 Systemic Lupus International Collaborating Clinics (SLICC) criteria introduced further requirements for the diagnosis of SLE. Diagnosis now requires either a positive biopsy in the setting of antinuclear antibodies or anti-DNA antibodies. If a biopsy is not available, the diagnosis can be established by meeting four of the now expanded 17 criteria; however, in addition to clinical features, one of the immunological criteria also needs to be present.3
With the introduction of the SLICC 2012 classification system requiring both clinical and immunologic criteria, cutaneous lupus erythematosus (CLE) was differentiated from the diagnosis of SLE.4 In contrast to the diagnosis of SLE that has been precisely defined, the diagnosis of CLE is only based on the presence of one mucocutaneous criterion; laboratory or histologic findings help guide the diagnosis.5 Based on these clinical, laboratory, and histologic findings, CLE is subdivided into acute cutaneous lupus erythematosus (ACLE), subacute cutaneous lupus erythematosus (SCLE), and chronic cutaneous lupus erythematosus (CCLE). DLE is the most common form of CLE.4
DLE prominently affects the face, ears (Figure 1), scalp, and neck. Lesions begin as erythematous macules or scaly papules, and they subsequently grow into coin-shaped discoid plaques with atrophic white scarring.4 Older lesions may show postinflammatory hyperpigmentation, whereas active lesions reveal erythema within the white plaques (Figure 2).6,7 The clinical differential diagnosis of DLE includes lupus vulgaris, sarcoidosis, and tinea faciei.8
DLE is associated with adherent follicular hyperkeratosis referred to as the “carpet-tack sign.”4,9 This refers to the keratotic spike, which is found on the bottom of a removed scale caused by the accumulation of keratin in the hair follicles.6 The ear is a common site of hyperkeratotic DLE lesions (Figure 1).4,9
The features of SCLE and ACLE are summarized in the Table.4-9
All subtypes of CLE demonstrate a lymphocytic infiltrate at the dermoepidermal junction. This is often referred to as an “interface-dermatitis,” and there can also be vacuolar alteration of the basal layer.9 Thickening of the basement membrane can be seen in progressive disease and highlighted by periodic acid-Schiff staining.9 Hyperkeratosis and keratotic follicular plugging can be observed in DLE; in addition, there can be either atrophy or hyperplasia of the epidermis.5,9 Direct immunofluorescence of lupus erythematosus shows IgG and/or IgM deposition along the basement membrane.10
Antibodies to nuclear antigens can be helpful to diagnose CLE. However, no specific antibodies differentiate between the subtypes with the exception of the anti-Ro/Sjögren syndrome A (SSA) and anti-La/Sjögren syndrome B antibodies for SCLE.5 Autoantibodies for double-stranded DNA and Smith can be used to evaluate for systemic involvement.5
A study of 134 Caucasian men and women was performed to determine whether antibodies against anti-annexin 1 can be detected in the sera of patients with CLE. The sera of those individuals diagnosed with CLE was found to have anti-annexin 1 antibodies in significantly higher amounts than those without the disease. However, the laboratory values did not correlate with disease severity or progression.11
Prevention of new lesions is a mainstay of treatment for DLE. Avoidance of exposure to the sun, as well as the use of sunscreen, is an essential intervention. Topical therapies include corticosteroids and calcineurin inhibitors.12
DLE that is refractory to treatment or scarring can require the use of systemic agents. Antimalarials, such as hydroxychloroquine sulfate, are the first line of therapy. However, for skin lesions that are refractory to topical interventions and oral antimalarials, other systemically administered medications, such as corticosteroids, methotrexate, retinoids, rituximab (Rituxan), or thalidomide, may be necessary.12
Our patient’s skin lesions had been chronic for several years. A punch biopsy from a left infra-auricular plaque confirmed the suspected diagnosis of DLE. Microscopic examination of hematoxylin-eosin-stained sections showed hyperkeratosis, follicular plugging, epidermal atrophy, thickening of the epidermal basement membrane, and liquefaction degeneration of the basal layer of the epidermis. A superficial and deep perivascular and periadnexal inflammatory infiltrate, composed of lymphocytes and histiocytes, was also present. A periodic acid-Schiff stain confirmed the basement membrane thickening. A colloidal iron stain revealed increased dermal mucin. His laboratory studies showed lymphocytopenia and a positive antibody titer to Ro (SSA). His cutaneous lesions were treated with triamcinolone 0.1% cream twice daily; he was referred to a rheumatologist for additional management and periodic follow-up evaluation for possible systemic disease development.
DLE is the most common form of CCLE. It can present with erythematous macules or scaly papules, which can progress into coin-shaped discoid plaques with atrophic white scarring. Indeed DLE has been differentiated from systemic forms of lupus, based on the criteria from the ACR and SLICC. A classic feature of DLE was observed in our patient: the “carpet-tack” sign, a keratotic spike found on the bottom of removed scale caused by the accumulation of keratin. First-line therapies for DLE may include topical (corticosteroids or calcineurin inhibitors) and oral (antimalarial) agents. Patients with progressive or refractory disease may require systemic therapies. Periodic clinical and laboratory follow-up may be considered if systemic involvement, albeit less common, is suspected in an individual with DLE.
Dr Vondrak graduated from Touro University California College of Osteopathic Medicine in Vallejo, CA, and is currently in his family medicine residency at Mike O’Callaghan Federal Medical Center, 99th Medical Group at Nellis AFB, NV. Dr Cohen is an adjunct professor of dermatology at Touro University California College of Osteopathic Medicine and a dermatologist at San Diego Family Dermatology in National City, CA.
Disclosures: The authors report no relevant financial relationships.
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