Systemic lupus erythematosus and coexisting bullous pemphigoid: immunofluorescent investigations

An 18-year-old black woman with systemic lupus erythematosus (SLE) who subsequently developed a bullous eruption is presented. Direct immunofluorescent studies of a bulla and peribullous skin demonstrated a tubular band at the dermoepidermal junction diagnostic for bullous pemphigoid (BP). However, an atrophic plaque clinically and histologically characteristic for lupus erythematosus (LE) also demonstrated a tubular band instead of one of the LE bands. Indirect immunofluorescent studies employing normal human skin revealed peripheral, homogeneous, and particulate antinuclear antibody patterns with anti-IgG but were negative for circulating anti-basal zone antibodies. Therefore BP was dominant cutaneously, whereas SLE prevailed serologically. This case illustrates the diagnostic problems of a bullous eruption in an SLE patient and points out some unusual immunofluorescent findings.