The Different Types and Sub-Types of Cutaneous Lupus Erythematosus
Cutaneous features, known to appear 75 to 80% of all patients with lupus erythematosus (LE) (Vera-Recabarren et al., 2010), are classified as specific or nonspecific cutaneous manifestations.
Specific cutaneous LE may be further classified into acute cutaneous LE (ACLE), SCLE, chronic cutaneous LE (CCLE), and bullous LE.
Moreover, CCLE has subtypes, including discoid LE (DLE), lupus profoundus (LP), lupus tumidus (LET), and chilblain lupus.
Similar histology findings are seen in ACLE, SCLE, and CCLE, and the difference among these subtypes is not possible with histology only.
These findings are commonly observed in dermatomyositis, and deliberate clinical examination is required to make a proper diagnosis.
The clinical appearance and prognosis differ between the different categories of CLE.
Approximately 25% of all patients with CLE progress to systemic disease; however, almost 100% of patients with ACLE progress to systemic disease, compared with only 5% of patients with CCLE and 30% of patients with SCLE (Vera-Recabarren et al., 2010).
Patients with generalized DLE are at a higher risk of progressing to systemic disease than those with a localized variant of the disease (Lee, 2008).
Acute cutaneous lupus erythematosus (ACLE) is normally confined to the face with malar erythema but can extend to a generalized distribution. The malar rash appears as symmetrical erythematous plaques across the malar eminences and nasal bridge, with sparing of the nasolabial folds.
The generalized variety involves a morbiliform or exanthematous eruption, which is worst on the outside surfaces of the arms with sparing of the knuckles.
In cases, where the trunk is involved, a triangular pattern of lesions is usually seen.
There is a rare subtype of ACLE that appears with bullous lesions and mucosal involvement, mimicking toxic epidermal necrolysis.
The lesions linked with ACLE are nonscarring but may develop postinflammatory pigment changes. The cutaneous disease activity tends to flare in parallel with the systemic manifestations of the disease.
ACLE’s histopathology shows an interface dermatitis, with mild focal vacuolar alteration of the basal layer. There is usually mucin in the upper dermis with follicular plugging, but epidermal thickening is uncommon.
Sub-acute cutaneous lupus erythematosus (SCLE) is featuring a nonscarring photosensitive eruption with psoriasiform or annular lesions on the face, V area of the neck, or extensor surfaces of the arms and upper back (Fig. 1). Less commonly, SCLE can present in an acral distribution as exfoliative erythroderma or with vesiculobullous lesions at the periphery of plaques. SCLE is associated with positive Ro/SSA antibodies and can overlap with other autoimmune disorders, such as Sjögren syndrome, rheumatoid arthritis, and Hashimoto’s thyroiditis.
Histopathology is the same to what is seen in other CLE subtypes and also shows interface dermatitis with vacuolar alteration of basal keratinocytes with areas of lichenoid dermatitis.
Mucin deposit is observed in conjunction with perivascular and periadnexal mononuclear cell infiltrate. The usual features of follicular plugging, dermal melanophages, and hyperkeratosis seen with DLE may be present, but to a lesser extent.
Patients with SCLE who acquire systemic disease tend to have relatively mild symptoms, limited to joint involvement.
A severe disease (e.g., lupus nephritis or central nervous system manifestations) is observed in <10% of SCLE cases (Okon and Werth, 2013).
Moreover, DLE is the most common subtype of CCLE and presents with characteristic indurated discoid lesions with an overlying scale, predominantly on the face and scalp.
Scarring alopecia associated with DLE should be differentiated from nonscarring alopecia associated with SLE.
The less common variety of CLE Include hypertrophic DLE, which affects the surface of the arms, and acral and mucosal variants.
The classic carpet tack sign (or tin tack sign) is present in DLE lesions, whereby keratotic spikes, similar in appearance to carpet tacks, are seen on the underside of the adherent scale when it is lifted. DLE has the potential for significant scarring and postinflammatory hypo- and hyperpigmentation. Long standing lesions can develop squamous cell carcinoma.
LP is a subtype of CCLE in which the inflammation is in the lower dermis and subcutaneous tissue and presents as nodular lesions that are approximately 1 to 3 cm in diameter, with tethering of the overlying skin. If confined to subcutaneous tissue only, the disease is referred to as lupus panniculitis.
Chillblain lupus, another subtype of CCLE, shows as purpuric patches and plaques on acral surfaces and face that are aggravated by cold. They also often have concurrent DLE lesions and develop scarred atrophic plaques with telangiectasia as the lesions
On the other hand, another subtype of CCLE is LET, which presents with edematous urticarial plaques that affect the face and trunk.
Histology shows periadnexal and perivascular inflammation and mucin deposition.
LET is not commonly linked with interface dermatitis and is clinically more photosensitive than other subtypes of CLE.
LET goes away without scarring and is less likely to progress to systemic disease, with affected patients often having a normal autoantibody profile.
Generally, LET has a better prognosis than other CLE subtypes, and lesions can spontaneously resolve within days or weeks of onset (Kuhn et al., 2005).