Lupus erythematosus (LE), an autoimmune disease, shows a wide range of clinical and cutaneous manifestations. Besides the well-known typical cutaneous manifestations of LE, there are also some rarer but characteristic cutaneous manifestations, which enable the dermatologist and the general practitioner who know them to suspect cutaneous LE (CLE) and investigate a possible underlying systemic involvement. 

Clearly, a skin manifestation is the first presentation of systemic LE (SLE) and >75% of SLE patients exhibit signs of skin disease during the course of the illness. 

Specifically, SLE involvement occurs in cases of acute CLE, while it is uncommon in subacute CLE and rare in chronic CLE. 

A recent review describes atypical cutaneous manifestations of LE to enable the clinician to diagnose even the rarest forms of CLE.

Rare forms of acute CLE (ACLE):

Generalized ACLE – It presents as a maculopapular or urticarial rash, particularly on sun-exposed skin, and characteristically involves the extensor aspects of the fingers and sparing of the knuckles.

Bullous LE – It presents as vesicles and bullae arising prevalently on sun-exposed skin, on erythematous or clinically normal skin. Erosions and crusts can also be observed and mucosal membranes can also be affected.

Rare forms of subacute CLE (SCLE):

They are mainly annular and papulosquamous (“psoriasiform”) forms which are characterized by photosensitivity and symmetrical distribution on sun-exposed areas, with recurrent skin lesions.

Erythrodermic LE – It is a very rare presentation of SCLE, which manifests with generalized exfoliative erythroderma, typically after sun exposure.

Lupus erythematosus gyratus repens – It is an annular variant of SCLE, showing widespread chronic-recurrent figurate erythematous plaques. 

Erythema annulare centrifugum-like LE – It shows annular erythematous plaques with a trailing scale. 

Rare forms of chronic CLE (CCLE):

It is characterized by a slow progression and a chronic clinical course. Discoid LE (DLE) is the most common clinical variant of CCLE, which mainly involves the head and neck area, representing localized DLE (LDLE), while the disseminated form of DLE extends below the neck, especially on the extensor surface of the arms.

Hypertrophic DLE – Hypertrophic or verrucous DLE is a rarer form with a characteristic of very pronounced hyperkeratosis. The lesions typically involve the face and the extensor surfaces of limbs, soles and palms. They appear as single or multiple papular or nodular lesions covered with a keratotic scale or as plaques covered with a multilayered, adherent horny yellowish or white substance, or as diffuse hyperkeratosis looking like chalky dust applied on the skin.

Lupus comedonicus – It is an uncommon presentation of DLE. Thirty-one percent of comedonal CCLE patients have concomitant SLE. 

Lupus mastitis – It occurs in patients aged 18 to 70 years and usually in females. It is mostly chronic with remission and flares.

Other forms of atypical CLE:

They have a rapid or more gradual cutaneous progression along with a spectrum of clinical and histological manifestations from ACLE to SCLE and DLE. They show a prominent systemic involvement.

Papulonodular mucinosis in LE – It presents as asymptomatic skin-colored papules and nodules, typically involving the trunk and upper limbs, along with other areas.

Linear LE – It is a very rare variant of CLE showing along the Blaschko lines and is described mostly in the pediatric age and young adults, with facial predilection and less frequently involving the trunk and limbs.

Monogenic LE – It is a rare form of LE occurring due to single gene mutations.

Toxic epidermal necrolysis (TEN)-like LE and erythema exsudativum multiforme (EEM)-like LE/Rowell syndrome – It is a severe and even life-threatening, but rare form of CLE.

TEN-like LE causes widespread detachment of the skin (positive Nikolsky sign) and the mucous membranes, which may be triggered by disease flares, e.g., following intensive UV exposure.

EEM is characterized by speckled ANA as well as possible anti-Ro or anti-La antibodies and rheumatoid factor. 

This illustration will help dermatologists to suspect and possibly diagnose even the rarest forms of CLE, with relevant support of immunofluorescence.

Source: Herzum A, Gasparini G, Cozzani E, et al. Atypical and rare forms of cutaneous lupus erythematosus: the importance of the diagnosis for the best management of patients. Dermatology. 2022;238(2):195-204.