Antibodies to the beta-4 integrin subunit of alpha-6-beta-4 integrin is shown to be associated with ocular disease while oral involvement is suggested to be linked with antibody reaction towards the alpha-6 subunit. Besides, MMP with antibody reaction against laminin 332 has an association with an increased risk for internal malignancy. Similar to bullous pemphigoid, other factors such as genetic factors, environmental exposures and the phenomenon of epitope spreading potentially result in MMP. Multiple studies have also reported an association of HLA-DQB1*0301 with MPP. Diagnosis
Diagnosis of bullous pemphigoid includes clinical assessment, skin biopsy for histopathology and direct immunofluorescence, indirect immunofluorescence and ELISA test. Among all, direct immunofluorescence is the gold standard for diagnosis of mucous membrane pemphigoid. Clinical assessment
Presence of tense blisters and erosions that occur on skin without another identifiable cause. Desquamative gingivitis or mucositis involving oral, ocular, nasal, genital, anal, pharyngeal, laryngeal, and/or esophageal mucosae
Presence of pruritic eczematous eruptions, or urticarial plaques without identifiable cause. Patients age over 60 years old. Histopathology
Lesional tissue, preferably of an intact vesicle or the edge of an intact bulla is obtained using punch biopsy for Haemotoxylin and Eosin (H&E) staining. The findings are sub-epidermal blister with dermal infiltrated with lymphocytes, neutrophils and eosinophils. Additional findings include sub-epidermal fibrosis which is consistent with the scarring nature of mucous membrane pemphigoid in older lesions and plasma cell infiltration. Direct immunofluorescence studies
Direct immunofluorescence (DIF) studies involves directly detecting tissue bound antibodies. Biopsy specimens for DIF should be taken from perilesional skin instead of lesional skin for H&E histopathologic evaluation.
Other classes of immunoglobulins such as IgM and IgA are present in approximately 20% of cases and usually are less intense. In some cases with the deposits of IgA, patient may have oral lesion. At early stages of the disease, only C3 may be present. Indirect immunofluorescence
Indirect immunofluorescence is used to detect circulating antibodies targeting the antigens at the basement membrane zone in patients with pemphigoid. In this procedure, patients serum is collected and overlaid on salt-split normal human skin and incubated. Following this, the specimen will be stained for fluorescent detection of antibodies. In bullous pemphigoid, circulating IgG targeting the basement membrane, mainly BP180 and BP230 hemidesmosomal proteins are detectable in 60-80% of patients. IgA and IgE classes can also be detected, but less frequently. Enzyme-linked immunosorbent assay (ELISA)
ELISA for bullous pemphigoid are commercially available to test for circulating Ig against NC16A domain of BP180 and BP230, known as bullous pemphigoid antigen 2 [BPAg2] and bullous pemphigoid antigen 1 [BPAg1] respectively. Antibodies to BP180NC16A domain is useful for the diagnosis of bullous pemphigoid as it has a sensitivity of 89% and specificity of 98%.Detection of BP180 and/or BP230 antibodies in serum does not give a confirmative diagnosis of bullous pemphigoid. A study has reported that 7% were tested positive for one or both autoantibodies in one series of 337 people without bullous pemphigoid. ELISA findings should be correlated with DIF to reduce the risk of misdiagnosis. Treatment
The treatment for bullous pemphigoid include:
1. Corticosteroids
i. Topical Corticosteroids
ii. Systemic corticosteroids
2. Glucocorticoid-sparing drugs
i. Immunosuppressive drugs
ii. Anti-inflammatory drugs
3. Biologic therapy
i.