The Value of Type IV Collagen Immunohistochemical Staining in the Differential Diagnosis of Autoimmune Subepidermal Bullous Diseases.

Autoimmune subepidermal bullous diseases (AISBDs) exhibit various clinical presentations, histological appearances, prognoses, and responses to treatment. Many diagnostic techniques, such as direct immunofluorescence (IF), indirect salt-split skin IF, and enzyme-linked immunosorbent assays, are used in the differential diagnoses of AISBDs. However, these techniques require fresh frozen tissue, expensive laboratory equipment, and sophisticated laboratory techniques. The purpose of this study was to evaluate the value of type IV collagen immunohistochemical (IHC) staining for the differential diagnosis of AISBDs. Paraffin-embedded blocks of skin biopsies were selected from 28 patients with autoimmune subepidermal bullous diseases. Among these 28 cases, 24 patients exhibited bullous pemphigoid (BP), 2 exhibited epidermolysis bullosa acquisita (EBA), 1 exhibited linear immunoglobulin A dermatosis (LAD), and 1 exhibited bullous systemic lupus erythematosus (BSLE). Sections were stained for type IV collagen and examined to determine the location of type IV collagen in the subepidermal blister. Type IV collagen positivity was observed on the base of the subepidermal blister in patients with BP (24 of 24 cases) and LAD (1 of 1 case). Staining was observed on the roof of the blister in patients with EBA (2 of 2 cases) and BSLE (1 of 1 case), and irregular staining was also observed on the base in patients with EBA. In conclusion, type IV collagen IHC staining is a simple and useful diagnostic technique for the differential diagnosis of AISBDs.

Immunohistochemical localization of basement membrane laminin 5 and collagen IV in adult linear IgA disease.

BACKGROUND: Linear immunoglobulin A disease (LAD), also known as linear IgA bullous dermatosis, is an autoimmune disorder characterized by subepidermal bullae caused by IgA autoantibodies directed against several antigens located in the basement membrane zone of the skin. Laminin 5 (laminin-332) is considered a key component of the lamina lucida/lamina densa interface, which provides stable attachment of the epidermis to the dermis. Meanwhile, collagen IV is a major component of the lamina densa. Laminin 5 and collagen IV bind to the cell membrane and induce cytoskeletal rearrangements, which contribute to the basement membrane's final mat-like structure. The study aimed to evaluate the immunohistochemical staining of laminin 5 and collagen IV and to identify the site of blister formation in formalin-fixed, paraffin-embedded skin biopsies from adults with LAD. METHODS: Skin biopsies from 20 adult patients with LAD were subjected to routine hematoxylin-eosin as well as immunohistochemical staining of collagen IV and laminin 5. RESULTS: Linear staining was positive on the floor of the blister for laminin 5 in 65% and collagen IV in 90% of biopsies denoting that the site of separation in most cases of LAD is above the lamina densa. CONCLUSIONS: The use of laminin 5 and collagen IV immunohistochemistry can be considered as an adjuvant diagnostic tool and may aid in the identification of the site of blister formation in routine skin biopsies in adults with LAD.

Association of linear IgA bullous disease with ulcerative colitis: a case of successful treatment with infliximab.

Linear IgA bullous disease (LABD) has been reported in association with inflammatory bowel disease, in particular ulcerative colitis (UC). We reporting a 34-year-old female who developed LABD during a flare-up of UC. We administered infliximab, which has been approved for the treatment of UC; infliximab dramatically improved the cutaneous lesions and bowel symptoms. This is the first report showing a marked effect of infliximab on LABD. First, we hypothesize that infliximab works for UC and then calms down excessive production of inflammatory cytokines and autoantibodies, and so stricter control of UC by infliximab is beneficial against the skin condition of LABD. Second, we suggest that TNF-α production in the lesion of LABD is increased, so TNF-α plays an important role in developing cutaneous lesions. This case suggests that infliximab, a monoclonal antibody against TNF-α, is efficacious in the cutaneous symptoms of LABD.