Cutaneous lupus erythematosus: clinico-pathologic correlation

Cutaneous lupus erythematosus (CLE) is a chronic-relapsing disease. It is defined as a LE localized to the skin without any significant systemic symptoms. Its annual incidence is of 4 cases per 100,000 persons with a prevalence of 73 cases per 100,000 persons. The etiology is unknown but it is considered as a prototype of autoimmune disease in which genetic factors (HLA), environmental factors (photo exposure and cigarette smoking) and pharmacological agents play an important role. The most accepted classification includes three clinical variants: acute (ACLE), subacute (SCLE) and chronic (CCLE). A fourth variety is the intermittent form (ICLE) also called "lupus tumidus" (LET) which is considered by some authors a distinct form from CCLE. The skin lesions are subdivided into LE specific and LE non-specific. The latter have a considerable importance as a symptom of evolution of the disease towards a systemic form of lupus (SLE). The histopathology of CLE is characterized by an interface dermatitis with vacuolization of the basal layer, a predominantly lymphocytic, perivascular and periadnexal infiltrate, epidermal and follicular hyperkeratosis, deposit of positive PAS material at the dermo-epidermal junction leading to atrophic-cicatricial evolution. Depending on the clinical variants, these microscopic features are more or less evident and are associated with peculiarities such as deposits of mucin (SCLE and LET), involvement of the panniculus in LE panniculitis, disappearance of the adnexa (cicatricial alopecia). The relationship between SLE/CLE is still under study: the progression of CLE in SLE is reported in a variable percentage of cases ranging from 12 to 18%. CLE therapy is aimed at preventing recurrences and scarring outcomes. Photoprotection with clothing, chemical and physical sunscreens active on UVA and UVB radiations is very important. Topical therapy is based on the use of steroids and calcineurin inhibitors, while the systemic therapy includes hydroxychloroquine as the first drug of choice.