A 42-year-old African American man with a 15-year smoking history presents with well-demarcated erythematous plaques with scale on his ears, arms, and cheeks. He reports that the condition has persisted for the past 2 years. He has no personal or family history of psoriasis and has not started any new medications or used any new products. On examination, the patient has multiple erythematous and hyperpigmented plaques with white sclerotic centers.
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Cutaneous lupus erythematosus (CLE) is associated with a diverse array of dermatologic pathology. Under this umbrella is discoid lupus erythematosus (DLE), the most common subtype of chronic cutaneous lupus erythematosus (CCLE).1,2 Like all forms of CLE, discoid lupus can be, but is not always, associated with systemic disease. In fact, cutaneous lupus is 2- to 3-times more common than systemic lupus erythematosus (SLE) and thus often occurs independently.3 DLE most commonly presents in African American women as well-demarcated, coin-shaped lesions with central clearing that are susceptible to scarring alopecia.1,3 These lesions are diagnosed clinically, although histology and lupus band testing can be useful diagnostic tools.3 Treatment involves sun protection, smoking cessation, and medical therapy such as topical corticosteroids, topical calcineurin inhibitors, and systemic antimalarial therapy.1,3,4
DLE falls within the broad category of lupus erythematosus and more specifically cutaneous lupus. For context, the 4 major subtypes of CLE include CCLE, acute CLE (ACLE), subacute CLE (SCLE), and intermittent CLE (ICLE).2,3 Within the CCLE subtype is DLE, lupus erythematosus profundus, chilblain cutaneous lupus, and lupus erythematosus tumidus.3 DLE may occur in the setting of SLE; however, only one-quarter of patients diagnosed with SLE develop discoid cutaneous lesions.1 Conversely, only approximately 5% to 10% of those diagnosed with DLE will have progression to SLE.3 As many as 25% of patients with ACLE will have progression to SLE; consequently, the discoid variant is considered a relatively benign disease compared with the other cutaneous subtypes.3
The development of DLE involves an interplay between genetic, environmental, and immunologic factors.1,5 Some implicated genes include TYK2, IRF5, and CTLA4; these genes are also associated with development of SLE.1 Environmental risk factors for DLE include smoking, sun exposure, and certain medications; viruses have also been implicated as a potential inciting factor.1,4 Sun exposure and smoking are also particularly important for the development of CLE. Although the exact mechanism is unknown, some evidence suggests ultraviolet (UV) radiation triggers keratinocyte morphologic change and apoptosis.4 Analogously, smoking may increase apoptosis and increase photosensitivity.1 In addition, both risk factors stimulate the immune response. UV light induces the release of several factors, namely interferon (IFN), tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-10, and IL-17, from keratinocytes.4 These cytokines recruit inflammatory cells, initially CD4+ and eventually CD8+ T cells. Similarly, smoking has been shown to induce T-cell proliferation.1 In accordance with these immunologic factors, IFN types I (α and β) and II (γ) have been associated with the development of DLE.5 Increased production of type I IFNs by plasmacytoid dendritic cells has been found to contribute to the accumulation of autoimmune debris that causes DLE via increased production of apoptotic factors, such as TNF-related apoptosis-inducing ligand (TRAIL).5,6 INF-γ induces differentiation of naive T-cells to Th1 cells; in DLE specifically, cutaneous inflammatory infiltrates are predominately Th1 mediated.1,4-6
Clinically, DLE presents as well-demarcated, round, erythematous plaques that slowly become indurated with associated adherent follicular hyperkeratosis.1-3,7 Removal of this scale is painful and reveals keratotic spikes commonly known as the carpet tack sign.1-3 Peripheral expansion leaves an atrophic, hypopigmented central depression with telangiectasias.1,4 Active lesions eventually resolve; however, patients may experience persistent scarring alopecia as lesions tend to extend into the hair follicle.3 On rare occasions squamous cell carcinoma arises from old lesions.1,3,4 Aside from rash, arthralgia is the most common systemic complaint in patients with DLE.8 Of note, patients of any age can be affected by DLE; however, it most commonly affects middle-aged women.1,3
The distribution of lesions can further classify DLE into localized and disseminated variants. DLE occurs predominantly above the neck on the face, scalp, and ears.1,4 Localized DLE is limited to this distribution above the neck, while disseminated DLE presents with lesions below the neck as well.1 Only 20% of patients develop disseminated DLE, but this variant is associated with higher rates of SLE.1,2 Lesions on the trunk or extremities without distribution above the neck is uncommon in DLE.1 Mucosal surfaces such as the lips and the nasal, oral, and genital mucosa may also be involved.1,9 In some patients, these lesions display a classic photodistribution; however, development of lesions in sun-protected areas is also possible, and the role of UV radiation in the development of DLE is unclear.1,4
The diagnosis of DLE is made clinically based on patient history and physical examination; however, histology, direct immunofluorescence (DIF), and serologic studies may be necessary for confirmation when the diagnosis is unclear.3 Histologic examination of DLE lesions reveals a lichenoid reaction characterized by vacuolar degeneration and apoptotic keratinocytes (Civatte bodies).4 Lymphocytic infiltrate, follicular plugging, mucin deposition, and thickening of the basement membrane are also classic features of DLE.1,3,10 The lupus band test is another useful diagnostic tool with positive results in the majority of patients with DLE.1,3 This test detects the deposition of immunoglobulins and complement at the dermal-epidermal junction and is especially useful for the differentiation of SLE and CLE. Both diseases are associated with positive band testing of active lesions; however, only SLE will be positive for uninvolved skin.1 DLE bands most commonly consist of C3 and IgM deposits with lower incidence of certain antibodies, including antinuclear, dsDNA, anti-Smith (anti-Sm), and SSA/Ro antibodies, when compared with other CLE subtypes.3
The differential for DLE depends on the stage, location, and variant of disease. Early lesions can mimic psoriasis, sarcoidosis, and cutaneous T-cell lymphoma.3 Especially given limited mucosal involvement, buccal mucosal DLE can be mistaken for lichen planus. Hypertrophic lichen planus and keratoacanthomas can also mimic the rare hypertrophic variant of DLE. Other differentials include other CLE such as ACLE and SCLE, as well as scleroderma, mixed connective tissue disease, and rheumatoid arthritis.1,3
Early treatment is vital in DLE as lesions frequently lead to permanent hypopigmentation, scarring, and alopecia that can be disfiguring, especially for darker-skinned individuals.1 Although no medications have been approved specifically for the treatment of DLE, topical corticosteroids, topical calcineurin inhibitors, and systemic antimalarial therapy are used as first-line treatment.1,3,4 Sun avoidance and protection as well as smoking cessation are recommended for all patients.3,4 Intralesional administration or short courses of oral corticosteroids may be necessary for chronic lesions that are unresponsive to topical corticosteroids or calcineurin inhibitors.1 For refractory cases, immunosuppressive agents such as methotrexate, mycophenolate mofetil, azathioprine; biologics such as rituximab; immunomodulators such as dapsone and thalidomide; or retinoids may be considered.3,4 Thalidomide and lenalidomide have been shown to be effective for DLE; however, they are not considered first-line treatment as patients frequently relapse once medication is discontinued.1,4
A skin biopsy was performed on the patient in our case, the results of which were consistent with DLE. Oral hydroxychloroquine (antimalarial) and topical corticosteroids were prescribed, and the patient was advised to stop smoking and avoid sun exposure. Although his lesions have improved, hypopigmented scars remain.
Anna D. Poliner, BSA, and McKenna E. Boyd, BS, are medical students at Baylor College of Medicine in Houston, Texas. Christopher Rizk, MD, is a dermatologist with Elite Dermatology in Houston, Texas.
- McDaniel B, Tanner LS. Discoid lupus erythematosus. StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2019.
- Kuhn A, Landmann A. The classification and diagnosis of cutaneous lupus erythematosus. J Autoimmun. 2014;48-49:14-19.
- Okon LG, Werth VP. Cutaneous lupus erythematosus: diagnosis and treatment. Best Pract Res Clin Rheumatol. 2013;27(3):391-404.
- Ribero S, Sciascia S, Borradori L, Lipsker D. The cutaneous spectrum of lupus erythematosus. Clin Rev Allergy Immunol. 2017;53(3):291-305.
- Kahn JS, Deverapalli SC, Rosmarin DM. JAK-STAT signaling pathway inhibition: a role for treatment of discoid lupus erythematosus and dermatomyositis. Int J Dermatol. 2018;57(8):1007-1014.
- Zhang Y, Wu J, Han Y, Shi Z, Wang L. Pathogenesis of cutaneous lupus erythema associated with and without systemic lupus erythema. Autoimmun Rev. 2017;16(7):735-742.
- Walling HW, Sontheimer RD. Cutaneous lupus erythematosus: issues in diagnosis and treatment. Am J Clin Dermatol. 2009;10(6):365-381.
- Oh EH, Kim EJ, Ro YS, Ko JY. Ten-year retrospective clinicohistological study of cutaneous lupus erythematosus in Korea. J Dermatol. 2018;45(4):436-443.
- Salah E. Clinical and dermoscopic spectrum of discoid lupus erythematosus: novel observations from lips and oral mucosa. Int J Dermatol. 2018;57(7):830-836.
- Elman SA, Joyce C, Nyberg F, et al. Development of classification criteria for discoid lupus erythematosus: results of a Delphi exercise. J Am Acad Dermatol. 2017;77(2):261-267.