Combined Intraepidermal–Intranuclear IgG and “Full-House” Immunoreactant Deposition at the Dermoepidermal Junction in Patients With Bullous Systemic Lupus Erythematosus

Bullous systemic lupus erythematosus (BSLE) is a relatively uncommon autoimmune bullous dermatosis presenting with bullae, neutrophil-rich subepidermal blisters, deposition of IgG, and frequently IgA, IgM, and C3 at the dermoepidermal junction (DEJ) in a “full-house” pattern. We describe the combination of intraepidermal, intranuclear IgG (IEIN), along with full-house DEJ deposition in patients with BSLE. Fifty-seven direct immunofluorescence images were reviewed for 6 years. IEIN deposition of IgG was identified in 8 patients: all with concurrent IgG/IgM/IgA/C3 in a linear/continuous granular pattern at the DEJ and a diagnosis consistent with BSLE. Eight of 11 (72.7%) patients with BSLE had dual patterns. All patients with dual patterns had blisters and 50% had concurrent urticarial lesions. Three carried a pre-existing diagnosis of systemic lupus erythematosus (SLE), while histopathologic/immunofluorescence findings triggered investigation and confirmation of systemic lupus erythematosus in 5. IEIN IgG had a speckled appearance and correlated with antinuclear antibody positivity (100%). IEIN speckled appearance likely represents antibodies against extractable nuclear antigens (ENA, evaluable in 6/8, present in all of these). Variable combinations of anti-ENAs were seen. In autoimmune bullous dermatosis evaluation, combined IEIN/DEJ suggests BSLE even if patients do not have a known SLE diagnosis. Antinuclear antibody and ENA panels should be recommended.