When a patient initially presents with discoid lupus, the doctor should ensure that the patient does not have
systemic lupus erythematosus. The doctor will order tests to check for
anti-nuclear antibodies in the patient's serum,
low white blood cell levels, and
protein and/or
blood in the urine. In order to help with diagnosis, the doctor may peel off the top layer of
scale from a patient's lesions in order to look at its underside. If the patients do indeed have discoid lupus, the doctor may see tiny spines of keratin that look like carpet tacks and are called
langue au chat. Diagnosis is confirmed through biopsy. Typical biopsy findings include deposits of
IgG and
IgM antibodies at the dermoepidermal junction on
direct immunofluorescence. 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,
Bowen's 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. In addition to lesions in the typical above-the-neck locations, patients with generalized discoid lupus often have lesions on the
thorax and the
arms. These patients are often
bald, with abnormal
skin pigment on their scalp, and have severe
scarring of the
face and arms. Patients with generalized discoid lupus often have abnormal lab tests, such as an elevated
ESR or a
low white blood cell count. They also often have
auto-antibodies, such as
ANA or
anti-ssDNA antibody. Childhood When patients develop discoid lupus in childhood, it differs from typical discoid lupus in several ways. Boys and girls are equally affected, and these patients later develop
SLE more often. These patients also typically do not have any abnormal sensitivity to the sun.
Special types of discoid lupus lesions Hypertrophic lupus Some experts consider
hypertrophic lupus erythematosus—which consists of lesions covered by a very thick,
keratin-filled scale—an unusual subset of discoid lupus. Others consider it a distinct entity.
Lupus profundus If a patient has discoid lupus lesions on top of
lupus panniculitis, they have lupus profundus. These patients have firm, nontender nodules with defined borders underneath their discoid lupus lesions.
Systemic lupus erythematosus with discoid lupus lesions In general, patients with discoid lupus who have only skin disease and no systemic symptoms have a genetically distinct disease from patients with
SLE. However, 25% of patients with SLE get discoid lupus lesions at some point as part of their disease. == Treatment ==