1. Lupus erythematosus: manifested by banded or granular deposits of IgG, IgM and C3 in the basement membrane bands; 2. Herpetiform aspergillosis: manifested by banded deposits of IgG and C3 in the basement membrane bands, with deposits on the epidermal side seen in salt-fractured skin; 3. Pemphigus vulgaris: manifested by reticular deposits of IgG, IgA, IgM and C3 in the interspinous cells; Wen Guangdong, Department of Dermatology and Venereology, Peking University People’s Hospital; 4. Certain cutaneous vasculitis: manifested by IgM and C3 deposits in the vascular walls of the skin; 5. Linear IgA herpes and acquired herpetic epidermolysis bullosa may also manifest as direct immunofluorescence positivity.