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This finding is 90% sensitive; however, false positives can occur with biopsies of facial lesions. In addition, pathologists often see groups of white blood cells, particularly T helper cells, around the follicles and blood vessels in the dermis. The epidermis appears thin and has effaced rete ridges as well as excess amounts of keratin clogging the openings of the follicles. The basal layer of the epidermis sometimes appears to have holes in it since some of the cells in this layer have broken apart. The remains of skin cells that have died through a process called apoptosis are visible in the upper layer of the dermis and the basal layer of the epidermis.The differential diagnosis includes actinic keratoses, sebborheic dermatitis, lupus vulgaris, sarcoidosis, drug rash, Bowens disease, lichen planus, tertiary syphilis, polymorphous light eruption, lymphocytic infiltration, psoriasis, and systemic lupus erythematosus. Classification
Discoid lupus can be broadly classified into localized discoid lupus and generalized discoid lupus based on the location of the lesions. Patients who develop discoid lupus in childhood also have their own sub-type of disease.Hypertrophic lupus and lupus profundus are two special types of discoid lupus distinguished by their characteristic morphological findings.Finally, many patients with systemic lupus also develop discoid lupus lesions. Localized
Most people with discoid lupus only have lesions above the neck and therefore have localized discoid lupus erythematosus. Generalized
Rarely, patients may have lesions above and below the neck; these patients have generalized discoid lupus erythematosus.