Pathophysiology
The bullae are formed by an immune reaction, initiated by the formation of IgG autoantibodies targeting dystonin, also called bullous pemphigoid antigen 1, and/or type XVII collagen, also called bullous pemphigoid antigen 2, which is a component of hemidesmosomes. A different form of dystonin is associated with neuropathy. Following antibody targeting, a cascade of immunomodulators results in a variable surge of immune cells, including neutrophils, lymphocytes and eosinophils coming to the affected area. Unclear events subsequently result in a separation along the dermoepidermal junction and eventually stretch bullae. Diagnosis
Diagnosis consist of at least 2 positive results out of 3 criteria (2-out-of-3 rule): (1) pruritus and/or predominant cutaneous blisters, (2) linear IgG and/or C3c deposits (in an n- serrated pattern) by direct immunofluorescence microscopy (DIF) on a skin biopsy specimen, and (3) positive epidermal side staining by indirect immunofluorescence microscopy on human salt-split skin (IIF SSS) on a serum sample. Routine H&E staining or ELISA tests do not add value to initial diagnosis. Treatment
Treatments include topical steroids such as clobetasol, and halobetasol which in some studies have proven to be equally effective as systemic, or pill, therapy and somewhat safer. However, in difficult-to-manage or widespread cases, systemic prednisone and powerful steroid-free immunosuppressant medications, such as methotrexate, azathioprine or mycophenolate mofetil, may be appropriate. Some of these medications have the potential for severe adverse effects such as kidney and liver damage, increased susceptibility to infections, and bone marrow suppression. Antibiotics such as tetracycline or erythromycin may also control the disease, particularly in patients who cannot use corticosteroids.
excision of the tumor’s protruding portion followed by treatment of the proximal perionych [i.e., skin around a nail] with phenol to eradicate the root of the tumor); and in individuals with tuberous sclerosis, topical application of sirolimus, i.e. rapamycin, (1% solution). Some of the latter methods have been used in order to preserve the nail matrix and nailplate and may be ideal for younger patients with few tumors since they may leave a normal appearing nail. See also
List of cutaneous conditions
Nail anatomy


== References ==