When approaching a patient with a blistering disease, it is important to first categorize the type and distribution of blisters, said Megan Holben Noe, MD, MPH, MSCE, a dermatologist from Brigham and Women’s Hospital in Boston. Other important historical factors include patient’s age, timing, comorbidities, outdoor exposures, new medications, and family history. Dr. Noe, who lectured at SDPA’s Summer Conference in Boston, recommends separate biopsy specimens for H& E and DIFs be obtained. Ideally, when obtaining the H&E specimen, this will be taken from the lesional skin, with the DIF specimen coming from perilesional skin. Additional features of the diagnostic workup may include serum immunofluorescence studies, laboratory tests to identify underlying comorbidities and microbial tests as needed.
Coverage: SDPA Annual Summer Dermatology Conference, June 22-25, 2023 – BOSTON
Next, Dr. Noe reviewed the more common bullous presentations. Edematous bullae present most commonly in the patient with chronic edema and will resolve when edema improves. Severe contact dermatitis, such as with contact with poison ivy, can present as bullae localized to the site of contact and requires treatment with high potency steroids. Bullous impetigo is caused by the exfoliative toxin produced by S.aureus that can be cultured from blister fluid and treated with topical antibiotics. In the patient with tinea pedis, it is important to consider bullous tinea pedis in the patient who presents with bullae on the medial foot and treatment can be accomplished with topical or oral terbinafine. While herpes zoster is a presentation with which most of us are familiar, it is important to consider the immune state of the patient. Patients who are immunosuppressed can present with disseminated zoster which may have internal and CNS involvement.
Generalized bullous fixed drug eruption is a rare variant and important mimicker of Stevens-Johnson-Syndrome. Patients with these conditions tend to present with widespread lesions without mucosal involvement. The approach to a patient with a suspected drug eruption should be counseled to stop any possible causative agents and non-essential medications before confirming the diagnosis and drawing additional labs. Most of these patients will require supportive care with consideration of treatment with systemic steroids or immunosuppressive agents. Lastly, Dr. Noe differentiated pemphigus and pemphigoid. Drug-induced bullous pemphigoid is most often caused by gliptins, PD-1 inhibitors, loop diuretics and penicillin. While it is essential to withdraw the medication, further treatment of bullous pemphigoid is required. Additional conditions reviewed by Dr. Noe included dermatitis herpetiformis, mucous membrane pemphigoid, linear IgA bullous dermatosis and bullous lupus.
Byline: Sarah B.W. Patton
Pictured: Megan Holben Noe, MD, MPH, MSCE