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[9 min read] Diagnosing blistering dermatoses in an older adult
Patients with blistering dermatoses can be difficult to treat. After ruling out more common causes such as allergic contact dermatitis or bullous impetigo, it’s time to dive into the realm of autoimmune or autoinflammatory blistering diseases. As a general practitioner without access to specialist care, taking care of a patient with blistering disease can be quite intimidating. Here are some tips for managing a patient whom you suspect may have a blistering skin disorder.
If your patient is an older patient (50+), then there are a group of disorders that are much more common in that age group. They are collectively known as pemphigus and pemphigoid disorders, which differ in both clinical presentation and pathogensis.
Pemphigus vulgaris and related disorders
Of the pemphigus diseases, pemphigus vulgaris (vulgaris meaning “common” in Latin) is by far the most common type of pemphigus in much of the world. The disease occurs due to autoantibodies directed at desmoglein proteins, which make up desmosomes holding keratinocytes together in the skin.
Pemphigus vulgaris can involve the mucous membrane, such as the eye, gumline, genitals, and even oesophagus. Pemphigus disease can be life-threatening if the blisters are widespread, subjecting them to fluid loss and infections much like a burn patient. Variants of pemphigus include pemphigus foliaceous, paraneoplastic pemphigus, and mucous membrane pemphigus.
Diagnosis of pemphigus is best done using skin biopsy for direct immunofluorescence. Immunofluorescence testing for circulating autoantibodies in the serum can be extremely helpful as well and can be helpful for monitoring treatment response.
Paraneoplastic pemphigus requires a special mention, as it may be the first presenting sign of an underlying lymphoma. Signs that may clue you in to this diagnosis include severe mucositis, eye involvement with scarring, and blistering involving the palms and soles, all of which are more likely to be seen in paraneoplastic pemphigus compared to pemphigus vulgaris. This condition has a high mortality rate and urgent work up for underlying haematologic or solid tumour malignancy is crucial if suspected.
Bullous pemphigoid and related disorders
Bullous pemphigoid is the most common autoimmune blistering disorder. It can be differentiated from pemphigus vulgaris by both the blisters as well as histology. Blisters in bullous pemphigoid are tense and fluid filled, where as blisters in pemphigus are flaccid. This is because bullous pemphigoid splits below the basement membrane of the epidermis, where as pemphigus splits within the epidermis itself. This difference can be confirmed on histology when a skin biopsy is taken for clinical work up. Bullous pemphigoid is caused by autoantibodies targeted to proteins that make up hemidesmosomes, which anchor the epidermis to the dermis in our skin. Some patients have lesions in their mouth, but this occurs much less often compared to pemphigus patients.
Diagnosing bullous pemphigoid
Diagnosis can be made by direct or indirect immunofluorescence to detect autoantibodies in either serum or skin specimens. Nowadays, ELISA techniques also offer a very sensitive and non-invasive serum test option to detect serum autoantibodies that cause bullous pemphigoid. As with pemphigus, treatment response often correlates with serum levels of circulating autoantibodies.
Treatment of most common types of pemphigus and pemphigoid
First-line treatment of both bullous pemphigoid and pemphigus vulgaris involves oral steroids with a taper to a steroid-sparing immunosuppressant. Often times, management of severe disease will require specialist care such as rheumatology or dermatology. Mild cases may be managed with tetracycline antibiotics in combination with nicotinamide alone, sometimes in combination with topical steroids. Some cases of pemphigus or pemphigoid may be drug induced. If drug-induced pemphigus or pemphigoid is suspected, removal of the offending drug is necessary as well. Common culprits include penicillamine and ACE-inhibitors, furosemide, and certain antibiotics.
Other serious blistering dermatoses that may mimic bullous pemphigoid
Other blistering dermatoses related to bullous pemphigoid include bullous lupus and linear IgA bullous dermatosis. These are conditions that should remain on the differential when you are working up your patient with a blistering disorder. Checking labs to rule out lupus and using direct immunofluorescence with skin biopsy can help you differentiate between these conditions. Some of these disorders, such as bullous lupus, will require further workup and management with a specialist as they may have poor prognosis without aggressive treatment.
Learn more in the Professional Diploma program in General Dermatology.
Ali Alikhan and Thomas L.H. Hocker. Review of Dermatology. 1st edition. Elsevier 2017. Chapter 3: General Dermatology.