Lupus erythematosus associated with C1 inhibitor deficiency.

We report here a patient with skin lesions of lupus erythematosus (LE) associated with a type 1 hereditary C1 inhibitor deficiency. She had not experienced any episodes of angioedema. A histological examination of the affected skin lesions demonstrated liquefaction of the basal cell layer in the perifollicule. Direct immunofluorescence staining revealed the granular deposition of IgM along the dermo-epidermal junction. Blood laboratory examinations revealed low levels of CH50, C1q, C4, C2 and C1 inhibitor, but the C3 and C5 levels were within normal limits. Similar reductions in the C1 inhibitor levels were observed in 2 out of 3 sisters. Although one sister has been asymptomatic until now, the other has suffered from SLE. The antinuclear antibody titer was negative initially, but has changed to positive. The skin lesions became pigmented following topical corticosteroid therapy, but the deficient complement component levels remained unchanged. We also reviewed 23 cases in the literature of hereditary C1 inhibitor deficiency associated with SLE, DLE, LE-like eruption, and SCLE and discussed several common characteristics such as a female predominance, a high incidence of antinuclear antibodies, cutaneous manifestations, and photosensitivity.