Most patients with discoid lupus erythematosus are asymptomatic, however, some patients may experience pain and pruritus in the lesions. A recent study revealed that 16% of patients with DLE may develop systemic manifestations of the disease within 3 years of onset of diagnosis. [3].

Systemic involvement of DLE presents with clinical features of SLE, therefore , there should be a detailed evaluation to detect serologic abnormalities, hematologic disorders, serosal inflammation such as pleuritis and pericarditis, neurological sequalae, and renal abnormalities. 

Malignant transformation of DLE is rare, however, skin cancer may be more common among blacks because of the absence of pigmentation in the chronic lesions, coupled with the chronic inflammation and continuous sun exposure. Risk factors for squamous cell carcinoma include lip involvement of lesions, early age of onset, smoking,  male gender, and recalcitrance of the disease [10].

Porphyria cutanea tarda is predominant in patients with cutaneous lupus erythematosus. Porphyria cutanea tarda may be triggered by antimalarial therapy as may lichen planus in these patients.

Lesions in DLE are usually characteristic comprising of erythematous papules or plaques with scaly appearances. As the lesions progress, the scales become thickened and coalescent. There may be central hypopigmentation of the lesions with hyperpigmentation at the active peripheral borders of the lesions. Lesions appear in a centrifugal pattern and may coalesce. These lesions heal with scars. The lesions may present with dilation of the follicular openings which are closed by keratinous plugs. Lesions are mainly found in the sun-exposed areas of the body.

The early lesions may be indistinguishable from those which occur in subacute cutaneous lupus erythematosus. The scalp is a very common site of occurrence of the skin lesions an it may result in irreversible alopecia.

In DLE, the lesions may be localized or generalized. Lesions are said to be localized if they involve only the head and neck regions, and when they affect additional areas of the body, they are described as generalized DLE. Generalized DLE is mostly associated with hematologic abnormalities and abnormal serologic findings. Furthermore, generalized DLE is more refractory to treatment and is more likely to be associated with SLE. The palms and soles are affected in less than 2% of patients with DLE. [11].

Some cases of DLE present with hypertrophic lesions which have a wart-like appearance, these lesions commonly affect the extensor arms and are generally unresponsive to treatment [12].

Lupus panniculitis is a form of chronic cutaneous lupus erythematosus which is characterized by inflammatory and destructive changes in the subcutaneous adipose tissue. This condition may coexist with DLE [13].

• Fatigue

  She complained of joint pain and fatigue. Clinical presentation, laboratory data, and histopathologic features were consistent with systemic lupus erythematosus in a patient with generalized chronic discoid lupus erythematosus. [ncbi.nlm.nih.gov]

  We ask about general symptoms (anxious mood, depressed mood, fatigue, pain, and stress) regardless of condition. Last updated: April 26, 2020 [patientslikeme.com]

  pretrvávajúca vyrážka, horúčka, bolesť kĺbov alebo svalov alebo únava Last Update: 2017-04-26 Usage Frequency: 1 Quality: English Signs of lupus or lupus-like syndrome, such as weight changes, persistent rash, fever, joint or muscle pain, or fatigue [mymemory.translated.net]

• Gangrene

  Areas of dead skin can appear as sores or small black spots at the ends of the fingers or around the fingernails and toes, causing gangrene (death of soft tissues due to loss of blood supply). [lupus.org]

  Rarely, fingers or toes with aggressive ulceration and gangrene may require amputation. Therefore, it is very important that you notify your doctor of any skin abnormalities. [hopkinslupus.org]

• Raynaud Syndrome

  syndrome ( see below ), (4) photosensitivity, manifested by unusual skin reaction after exposure to sunlight, (5) nondeforming arthritis, (6) inflammation… Read More [britannica.com]

  Lupus patients with Raynaud’s syndrome should keep their hands warm with gloves during cold weather. What Causes Lupus? No single factor is known to cause lupus. [webmd.com]

  Common manifestations may include arthralgias and arthritis, Raynaud syndrome, malar and other rashes, pleuritis or pericarditis, renal or central nervous system involvement, and hematologic cytopenias. [msdmanuals.com]

• Pallor

  On general physical examination, the patient was poorly nourished and weak, with signs of pallor. Review of systems revealed no significant abnormalities. [jiaomr.in]

• Reiter Syndrome

  A heterogenous group of diseases comprises nosologic units included in seronegative spondylarthritis: ankylosing spondylitis, Reiter’s syndrome (reactive arthritis), psoriatic arthritis, enteropathic arthritis, and according to some authors Behcet’s syndrome [aepress.sk]

• Easy Bruising

  Continued Sometimes, changes in blood counts (low red cell count, or anemia ), may cause fatigue, serious infections (low white cell count), or easy bruising or bleeding (low platelet count). [webmd.com]

• Abdominal Pain

  Other symptoms depend on which part of the body is affected: Brain and nervous system: Headaches, numbness, tingling, seizures, vision problems, and personality changes Digestive tract: Abdominal pain, nausea, and vomiting Heart: Valve problems, inflammation [medlineplus.gov]

  Manifestations may include abdominal pain resulting from serositis, nausea, vomiting, manifestations of bowel perforation, and pseudo-obstruction. SLE rarely causes parenchymal liver disease. [msdmanuals.com]

• Oral Ulcers

  Oral ulcers, findings on skin biopsy, a positive antinuclear antibody test, and transverse myelitis on MRI all confirm the presence of systemic lupus erythematosus (SLE). [atm.amegroups.com]

  Over the next 13 months, the patient developed severe photosensitivity, oral ulcers, Raynaud phenomenon, anemia, and nephrotic-range proteinuria. [mdedge.com]

  […] membrane ulcerations, often found on oral surfaces It is important to distinguish cutaneous lupus from systemic lupus erythematosus (SLE). [hss.edu]

  Other lesions associated with ACLE include oral ulcers, hives, and temporary hair loss, which are replaced by new hair once the disease flare is treated. [americanskin.org]

  Mouth ulcers Formation of thick scales may spread to the interior region of the mouth, causing open sores or oral ulcers. These open lesions in the mouth can often be painful. These may also multiply if allowed to spread further. [phaa.com]

• Arthralgia

  In some patients, arthralgia or arthritis may precede the onset of multisystem disease by many years [1]. [escholarship.org]

  Risk factors for the development of SLE include widespread DLE, arthralgias ⁄ arthritis, nail changes, anemia, leukopenia, an elevated ESR, and a positive test for antinuclear antibodies (ANA). [visualdx.com]

  In the remaining patient, the arthralgia has been severe and has warranted other systemic therapies. [jamanetwork.com]

  Responses With 3 Simultaneously Occurring Reactions Following Herpes Zoster Case Report A 19-year-old woman initially presented to an outside dermatologist for evaluation of new-onset scarring alopecia, crusted erythematous plaques on the face and arms, and arthralgia [mdedge.com]

  Some patients exhibit systemic symptoms, such as fatigue, myalgia, arthralgia, slight fever and laboratory tests may show abnormalities (see below). [ebm-guidelines.com]

• Joint Swelling

  They may sometime have symptoms of joint pain and joint swelling. In about 5% of the individuals with discoid lupus erythematosus symptoms of systemic lupus erythematosus may be seen. [steadyhealth.com]

  Common symptoms include: severe fatigue joint pain joint swelling headaches a rash on the cheeks and nose, which is called a “butterfly rash” hair loss anemia blood-clotting problems fingers turning white or blue and tingling when cold, which is known [healthline.com]

• Skin Lesion

  As the lesions grow they merge with each other. Resolution of these active skin lesions results in wasting and scarring of the skin. The skin lesions may have any or all the above mentioned features. [steadyhealth.com]

  This system separates skin lesions associated with LE into two groups. [doi.org]

  Active skin lesions require effective management in order to prevent scarring of the skin and consequent cosmetic issues. [ebm-guidelines.com]

  Discoid lupus erythematosus – Predominantly skin lesions during childhood. Subacute lupus erythematosus – Skin lesions during childhood. [visualdx.com]

  Abstract Lupus erythematosus is an autoimmune disease of unknown etiology with cutaneous and vascular lesions. Both discoid lupus erythematosus (DLE) and systemic lupus (SLE) affect the skin. [ncbi.nlm.nih.gov]

• Alopecia

  We report two cases of sarcoidal alopecia originally thought to represent DLE scarring plaques of the scalp. A subsequent histopathologic diagnosis of sarcoidal alopecia was made. [ncbi.nlm.nih.gov]

  Indian Dermatol Online J 2016;7:458 A 34-year-old female presented with cicatricial alopecia over the scalp with erythema, areas of atrophy and scaling and dyspigmentation [Figure 1]. [idoj.in]

  Cicatricial alopecia is the end stage of this inflammatory disease when it affects the scalp. [benthamopen.com]

• Skin Disease

  Various skin diseases may present with cutaneous horns including viral warts, actinic keratosis, keratoacanthoma, seborrhoeic keratosis, pyogenic granuloma, discoid lupus erythematosus, verruca vulgaris, Bowen's disease, basal cell carcinoma and squamous [ncbi.nlm.nih.gov]

  Definitions of discoid lupus erythematosus 1 n a chronic skin disease occurring primarily in women between the ages of 20 and 40; characterized by an eruption of red lesions over the cheeks and bridge of the nose Synonyms: DLE Type of: autoimmune disease [vocabulary.com]

  Discoid lupus erythematosus (DLE) is a chronic skin disease that mainly affects the skin of the face and other sun-exposed areas. It is distinctly rare in the oral cavity, and there are few evidence-based studies that document its treatment. [oooojournal.net]

• Ulcer

  We report a case of DLE, presenting with a six-month history of ulcerated fungating plaques and small crusted nodules superimposed on DLE plaques over both the forearms. [ncbi.nlm.nih.gov]

  Diffuse, irregular ulcers covered by a pseudomembraneous slough were noted [Figure 4] and [Figure 5]. On palpation, the ulcers are tender and bleed on slight provocation. [jiaomr.in]

  Erosions and ulcers were common but granulation tissue was limited and fibrosis (scarring) was not seen. [doi.org]

  Mucosal ulcerations Mucosal ulcerations are sores in the mouth or nose or, less often, in lining of vaginal tissue. These ulcers can be caused by both cutaneous lupus and systemic lupus. [lupus.org]

• Eruptions

  Previously, a discoid lupus erythematosus-like eruption linked to its use was rarely reported in patients with rheumatoid arthritis. We present a case of rheumatoid arthritis which developed such an eruption after treatment with infliximab. [ncbi.nlm.nih.gov]

  […] dermatitis -- Contact dermatitis -- Vesiculobullous disorders -- Pustular eruptions -- Lichenoid skin eruptions -- Granulomatous diseases of the skin -- Drug eruptions -- Vasculitis -- Deposition disorders -- Photosensitive dermatitis -- Disorders of [worldcat.org]

• Blepharitis

  A 28-year-old woman presented with a 2-year history of idiopathic, chronic blepharitis unresponsive to several courses treatment of corticosteroid eye drops. [ncbi.nlm.nih.gov]

  She had been treated for blepharitis and eczema with topical antibiotic and corticosteroid ointments. [dx.doi.org]

  Patients with this presentation will likely be treated as chronic blepharitis or eczema (7). [scielo.br]

  Discoid lupus erythematosus presenting as asymmetric posterior blepharitis. Am. J. [aaojournal.org]

• Malar Rash

  In patients with malar rash, AMS scores at one (8.30 ± 6.80, p CONCLUSIONS: Malar rash may be a marker of more severe systemic disease over time, while DLE has no significant impact on general SLE disease activity. © The Author(s) 2015. [ncbi.nlm.nih.gov]

  The ANA became strongly positive by ELISA and u… Publisher Full Text (DOI) StatPearls: Malar Rash [BOOK]. [unboundmedicine.com]

  These include: Malar rash - “butterfly rash” that appears on the cheeks Discoid rash - red patches on the skin that can lead to scarring Photosensitivity - sensitivity to sunlight/UV light which can lead to rashes and other symptoms Oral ulcers - mucosal [hss.edu]

• Kidney Failure

  Calcinosis can develop from a reaction to steroid injections or as a result of kidney failure. Cutaneous vasculitis lesions Cutaneous vasculitis lesions occur when inflammation damages the blood vessels in the skin. [lupus.org]

  Complications Inflammation caused by lupus can affect many areas of your body, including your: Kidneys. Lupus can cause serious kidney damage, and kidney failure is one of the leading causes of death among people with lupus. [mayoclinic.org]

  […] inflammation decreased kidney function kidney failure SLE can have serious negative effects on your body during pregnancy. [healthline.com]

• Headache

  If your brain is affected by lupus, you may experience headaches, dizziness, behavior changes, vision problems, and even strokes or seizures. Many people with lupus experience memory problems and may have difficulty expressing their thoughts. [mayoclinic.org]

  Inflammation of the nervous system and brain can cause memory problems, confusion, headaches, and strokes. Inflammation in the brain’s blood vessels can cause high fevers, seizures, and behavioral changes. [lupus.org]

  Pain in the chest after taking a deep breath Unexplained fever Edema (swelling), often in the legs or around the eyes Mouth sores Unexplained hair loss Raynaud’s phenomenon (characterized by cold fingers and/or toes that are pale or purple in color) Headaches [lifeextension.com]

  Common symptoms include: severe fatigue joint pain joint swelling headaches a rash on the cheeks and nose, which is called a “butterfly rash” hair loss anemia blood-clotting problems fingers turning white or blue and tingling when cold, which is known [healthline.com]

  She denied a history of headaches, seizures, fever, weight loss, cough, shortness of breath, and Raynaud phenomenon. She had not received any treatment for the previous year. [escholarship.org]

Baseline laboratory blood test is necessary in the diagnosis of DLE. These include complete blood count with the white blood cell count often reduced and erythrocyte sedimantation rate (ESR) which is typically raised. Rheumatoid factor may be positive in DLE. A negative result doesn't exclude DLE.

Serology is also important in the diagnosis of discoid lupus erythematosis. Serology reveals positive antinuclear antibody(ANA) findings in 20% of cases of DLE. Complements are often reduced. 

Urinalysis may be necessary to exclude renal involvement. Albuminuria suggests kidney involvement.

These laboratory investigations should be ordered periodically to determine the absence or presence of systemic progression.

Biopsy is the most sensitive and specific investigation for DLE. The features on histology are usually characteristic but may depend on the type and duration of the disease. A direct positive immunoflourescence is observed in the biopsy samples in most cases of DLE.

• Leukopenia

  After multivariable adjustment, DLE in SLE was significantly associated with photosensitivity (odds ratio [OR] 1.63), leukopenia (OR 1.55), and anti-Smith antibodies (OR 2.41). [ncbi.nlm.nih.gov]

  Risk factors for the development of SLE include widespread DLE, arthralgias ⁄ arthritis, nail changes, anemia, leukopenia, an elevated ESR, and a positive test for antinuclear antibodies (ANA). [visualdx.com]

  The diagnosis of SLE was based on the presence of photosensitivity and the detection of leukopenia, anemia and positivities of antinuclear antibody, anti DNA, and VDRL. [go.gale.com]

  […] significant risk of progression to SLE but may predict a milder phenotype of systemic disease.[6] The presence of DLE in patients with SLE has not been shown to be associated with less severe disease.[7] There are increased risks of photosensitivity and leukopenia [patient.info]

  Mild anaemia or leukopenia may be present in patients that do not have SLE A skin biopsy may be diagnostic, showing a lichenoid tissue reaction and features specific to the kind of cutaneous LE. [dermnetnz.org]

• Antinuclear Autoantibodies

  Wallace ; Antinuclear autoantibodies in cutaneous lupus erythematosus: biochemical and cell biological characterization of Ro/SSA / Anna von Mikecz -- Part IV: Treatment and management of cutaneous lupus erythematosus. [worldcat.org]

Treatment is aimed at controlling the existing skin lesions, preventing development of new lesions, preventing complications, and improving cosmesis.

Topical corticosteroids and antimalarials are the main drugs of choice for treating DLE.

Intralesional corticosteroids are the preferred form of administration of corticosteroids and are administered into the individual lesions. Oral corticosteroids are avoided because of adverse effects of prolonged use of the drug. A medium-strength corticosteroid such as triamcinolone is usually administered topically first. Low-strength corticosteroids such as hydrocortisone are preferable for facial lesions. However, if both forms of corticosteroids fail to resolve the symptoms, a high-strength corticosteroid such as bethametasone becomes necessary. These high potency corticosteroid are also recommended as first-line for hypertrophic lesions.

If the lesions remain unresolved upon treatment with topical and intraleional corticosteroid, antimalarials are considered with hydroxychloroquine being the drug of choice. If hydroxychloroquine produces no resolution of the lesions after a period of two months of therapy, chloroquine should be used. However, antimalarial therapy should be provided continuously for 1 to 2 years for complete resolution of the lesions. Corticosteroid treatment should be given concurrently with antimalarial treatment and should be discontinued after completion of antimalarial treatment.

In cases where antimalarial treatment is unsuccessful, immunosuppressant treatment is considered next. Effective immunosuppressants include azathioprine, mycophenolate mofetil, and methotrexate. These are also particularly effective in the treatment of refractory cases of DLE.

Oral thalidomide is considered if all other treatments have failed. However, thalidomide is recommended only for remission induction because of its tendency for neural damge. Although thalidomide neurotoxicity is not dose-dependent, low doses could be safe.

Studies have identified topical tacrolimus and pimecrolimus as useful alternative drugs in the treatment of DLE and other CLE lesions. These studies have not provided concrete evidence to establish their safety and effectiveness.

Supportive treatment for DLE include limited sun exposure especially during the hours when sunlight is most intense, usually between 10 am to 3 pm. Occlusive clothing and sunscreens are recommended. Smoking cessation is also critical in preventing progression and worsening of the disease. Cosmetic products to mask the lesions are also recommended.

In cases of DLE with telegiectasia and chronic erythema, surgery including photothermolytic ablation of the dilated vessels may be recommended. This procedure is called pulsed eye laser treatment and it has been shown to be very effective for recalcitrant cases of DLE. Surgical excision of scarred lesions is also effective, although it may reactivate latent lesions.

Discoid lupus erythematosus may not cause mortality, however, it may be associated with significant morbidity. The condition may cause significant burning and pain caused by the lesions, and considerable cosmetic problems. In a few cases, discoid lupus erythematosus may cause fatal sequelae if there is systemic involvement. Although malignant transformation of the lesions are rare, prompt skin biopsy is recommended in case of suggestive malignant lesions [10]. Sunlight is a known exacerbating factor of DLE lesions.

Several studies have identified smoking as a risk factor for DLE. These studies have also indicated ultraviolet radiation as a precipitating and aggravating factor of DLE [5] [6]. DLE may also develop within areas of skin which have been injured or affected by physical trauma, this is known as koebner phenomenon.

DLE is thought to be a result of autoimmune mechanisms as it has been linked to some major histocompatibility complex antigens. Other studies indicate that genetic factors may contribute to the etiology of DLE [7].

SLE has a worldwide prevalence of 17 to 48 cases per 100,000 people. SLE most commonly occurs in individuals aged 40-60 years with onset at the age of 20-30 years. SLE is commoner in women than men with a female to male ratio of 10:1.

DLE accounts for 50-85% of all cases of cutaneous lupus erythematosus and it is more common among women than men with a female to male ratio of 3:1.

DLE is also more common among African Americans than whites or Asians. DLE occurs most commonly among persons aged between 20 and 40 years, however, it may occur at any age.

The exact mechanism of development of cutaneous lupus erythematosus in general is not clearly understood. However, leading theories have indicated that an autoimmune process may be responsible for the disease. This is because of the identification of IgG and C3 in the epidermal basement membrane which is the site of the autoimmune damage [8].

In chronic DLE, as compared to acute and subacute cutaneous lupus erythematosus, there is a much higher concentration of inflammatory infiltrates which mostly comprise of T cells. Additionally, in chronic DLE , the inflammatory cell infiltrates extend to the deeper reticular dermis and subcutaneous tissue in contrast to findings in subacute and acute chronic lupus erythematosus in which the inflammatory cell infiltrates are confined to the outer dermis.

Researchers have suggested that apoptosis of keratinocytes may be the critical occurrence in the etiology of cutaneous lupus erythematosus [9].

To reduce triggers or flares of the lesions in discoid lupus erythematosus, restriction of exposure to sunlight is advised. This can be achieved by using occlusive clothing and sunscreens. UV-blocking films may be applied to window glasses to prevent reflection of sunlight into the rooms. However, vitamin D supplements are necessary because of the sunlight restriction. Smoking cessation also prevents precipitation of flares of DLE.

There are 3 subtypes of cutaneous lupus erythematosus (CLE) based on the onset and duration of lesions: acute, subacute and chronic. Each subtype presents with characteristic lesions.

Acute CLE is characterized by malar rash which may spread across the nasal bridge. The lesions do not involve the nasolabial folds. Furthermore, acute CLE may present with generalized morbilliform eruptions on the hands sparing the joint areas. Subacute CLE is characterized by annular plaques affecting sun-exposed areas only. Chronic CLE consists of three subdivisons including discoid lupus erythematosus, lupus panniculitis, and timid lupus.

The lesions in discoid lupus erythematosus are erythematous or violaceous plaques with a scaly appearance and a characteristic keratinous plugging on the openings of each lesion.The lesions typically heal with scarring.

DLE may be localized to the skin without systemic features. However, in other cases, it may progress to systemic lupus erythematosus (SLE). Approximately 16.7% of cases of DLE progress to SLE within 3 years from onset of DLE [2] [3]. Often, the secondary SLE manifestations do not fulfill more than 4 of the 11 criteria for the diagnosis of SLE as set by the American College of Rheumatology [4] 

Diagnosis of DLE is mainly clinical, however, series of laboratory investigations may be necessary to exclude systemic involvement. Serology may be needed to confirm antinuclear antibody (ANA) titers. Skin biopsy is the most sensitive test for DLE.

Treatment of choice for DLE is topical corticosteroid and antimalarials. Corticosteroids are the first line of treatment, while antimalarials and immunosupressants are used respectively if the preceeding medical therapy fails. Surgery may be considered for certain lesions.

Overview

Discoid lupus erythematosus (DLE) is a rare skin disease characterized by scaly and crusty rashes affecting mainly the sun-exposed areas of the body. Discoid lupus erythematosus is within a spectrum of skin diseases called cutaneous lupus erythematosus and it is characterized by only skin lesions. Another disease condition in this broad group is called systemic lupus erythematosus which causes both skin rashes and disorders of the internal organs. All of these diseases are worsened by sunlight.

Etiology

Although the cause of this skin condition is not fully understood, some researchers have suggested that it may result from autoimmune mechanism, which refers to a phenomenon whereby the body's antibodies attack different tissues in the body. This results because the antibodies confuse these tissues for foreign harmful materials from which they must protect the body. In the case of DLE, the antibodies confuse the normal skin cells for foreign objects and attack them causing the skin lesions . it is typically worsened by exposure to sunlight. Tobacco smoking and physical trauma to the skin have also been suggested to contribute to the development of this condition.

Epidemiology

DLE affects both sexes and all age groups, however, it is most common among women aged between 20 and 40 years.

Presentation

The skin presents with red, itchy, and scaly or crusty rashes which heal with bad scars. In some patients , there may be no symptoms at all. The only problem in patients with DLE is the bad appearance of their skin.

DLE typically causes skin rashes in the face and scalp, although could affect every other skin area. In the scalp, DLE could result in irreversible hair loss.

Diagnosis

Typically, a skin biopsy may be necessary to make a diagnosis of DLE, the biopsied sample is viewed under the microscope to detect unique features of this disease. Laboratory blood and urine tests are needed to exclude SLE which is the type that affects internal organs.

Treatment

DLE doesn't have a cure, the available drugs just help to reduce the symptoms of the disease. First of these drugs to be recommended and prescribed by a doctor is corticosteroid ointments or injections which are administered directly into the skin rashes. Corticosteroid tablets have more detriments than benefits, so would be avoided by doctors for the treatment of DLE.

If these drugs have been administered for a period, but the skin rashes do not improve, antimalarials would be prescribed. Now these drugs are not used because of their antimalarial effect, but because of their additional ability to suppress inflammation significantly. The commonest antimalarial used is hydroxychloroqine which could also be prescribed with mepacrine, another antimalarial , to increase its safety and effectiveness. The only concern with hydroxychloroquine is its ability to cause eye problems if taken at high doses. Doctors would conduct eye tests to determine if this drug is suitable for you.

After about 2 months of receiving antimalarial treatment, if no improvement is recorded, certain drugs which serve as suppressants of the immune system would be prescribed. Examples of these include methotrexate and azathioprine.

Self care is also important in the management and control of DLE. Important self-care tips include limiting your exposure to sunlight by using a good sunscreen and wearing clothes that cover your arms, shoulders and legs well. Dark clothing is preferable to reflect sun rays from the cloth. A hat is advised to reduce sun exposure to the face and scalp.

1. James, William; Berger, Timothy; Elston, Dirk. Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.) Saunders. Chapter 8. 2005.
2. Prystowsky SD, Gilliam JN. Discoid lupus erythematosus as part of a larger disease spectrum. Correlation of clinical features with laboratory findings in lupus erythematosus. Arch Dermatol. 1975 Nov; 111(11):1448-52.
3. Grönhagen CM, Fored CM, Granath F, Nyberg F. Cutaneous lupus erythematosus and the association with systemic lupus erythematosus: a population-based cohort of 1088 patients in Sweden. Br J Dermatol. 2011 Jun; 164(6):1335-41. 
4. Tan EM, Cohen AS, Fries JF, et al. The 1982 revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum. 1982 Nov; 25(11):1271-7.
5. Gallego H, Crutchfield CE 3rd, Lewis EJ, et al. Report of an association between discoid lupus erythematosus and smoking. Cutis. 1999;63:231-234.
6. Miot HA, Bartoli Miot LD, Haddad GR. Association between discoid lupus erythematosus and cigarette smoking. Dermatology. 2005;211:118-122.
7. Knop J, Bonsmann G, Kind P, et al. Antigens of the major histocompatibility complex in patients with chronic discoid lupus erythematosus. Br J Dermatol. 1990;122:723-728.
8. Seitz CS, Brocker EB, Trautmann A. Linear variant of chronic cutaneous lupus erythematosus: a clue for the pathogenesis of chronic cutaneous lupus erythematosus? Lupus. 2008;17:1136-1139.
9. Lin JH, Dutz JP, Sontheimer RD, et al. Pathophysiology of cutaneous lupus erythematosus. Clin Rev Allergy Immunol. 2007;33:85-106.
10. Tao J, Zhang X, Guo N, et al. Squamous cell carcinoma complicating discoid lupus erythematosus in Chinese patients: review of the literature, 1964-2010. J Am Acad Dermatol. 2012 Apr; 66(4):695-6.
11. Parish LC, Kennedy RJ, Hurley J. Palmar lesions in lupus erythematosus. Arch Dermatol. 1967 Sep. 96(3):273-6. 
12. Spann CR, Callen JP, Klein JB, Kulick KB. Clinical, serologic and immunogenetic studies in patients with chronic cutaneous (discoid) lupus erythematosus who have verrucous and/or hypertrophic skin lesions. J Rheumatol. 1988 Feb; 15(2):256-61.
13. Martens PB, Moder KG, Ahmed I. Lupus panniculitis: clinical perspectives from a case series. J Rheumatol. 1999 Jan; 26(1):68-72.