Table III.

Comparison of main features of psoriasis and systemic lupus erythematosus

Psoriasis	Lupus erythematosus
Skin lesions
Red plaques of skin that flake or develop scales The appearance of thick, white patches of skin called plaques on the elbows, knees, and other areas of the body, patches of skin that itch, crack, or bleed Shiny, red lesions in folds of skin Small red dots on the trunk, in the case of guttate psoriasis	A butterfly-shaped rash on the face Joint pain Body rashes, particularly after sun exposure Fingers or toes turning blue or white on exposure to the cold
UV
UV radiation – improves and inhibits lesions	UV photosensitivity – UV exposure worsening course of the disease
Genetic predisposition
HLA-B27, HLA-Cw6, HLA-DR7 and HLA-DRB1	HLA-DRB1, -DR3, -DR4, -DR9, -DR11 and -DR15
Musculoskeletal symptoms
Arthralgia Arthritis (if psoriatic arthritis develops)	Arthralgia, myalgia Jaccoud’s arthropathy, nonerosive arthritis
General symptoms
Not occur	Fever, malaise, fatigue, weight loss
Laboratory tests
Usually normal	Hemolytic anemia, Coombs positivity, thrombocytopenia, leucopenia, lymphopenia, increased ESR, low complement C3, C4, CH50, abnormal titer of ANA, antibody anti-dsDNA, anti-Sm, positive test results for anti-phospholipid antibody
Skin histopathology
Epidermal acanthosis, hyperkeratosis and parakeratosis (cell nuclei present) in the cornified layer. In the dermis, dilated and contorted blood vessels reach into the tips of the dermal papillae. An inflammatory infiltrate containing T-lymphocytes, macrophages, mast cells, and neutrophilic granulocytes within the dermis and epidermis [28]	Mild hyperkeratosis, atrophy of epidermis with effaced of ridge pattern, sometimes parakeratosis. Hair follicles are often unaffected or slight keratin plugging. In dermis lymphocytic exocytosis may be conspicuous and satellite cell necrosis. The inflammatory cell infiltrate is mild, superficially and perivascular located [29]
Skin immunofluorescence
Not characteristic	Deposition of immunoglobulins (IgG, IgM, IgA) and complement components in the skin, demonstrable as a linear band at the basement membrane zone by direct immunofluorescence (lupus band test, LBT) [29]