How can I differentiate pemphigus vulgaris from other blistering disorders in a primary care context?

In a primary care setting, differentiating pemphigus vulgaris (PV) from other blistering disorders relies primarily on clinical features and initial examination findings. PV typically presents with painful, flaccid blisters and erosions on the skin and mucous membranes, especially the oral mucosa, which is involved in the majority of cases early on. This mucosal involvement is a key distinguishing feature, as many other blistering disorders, such as bullous pemphigoid, rarely affect mucous membranes initially NICE CKS Guillen & Khachemoune 2007.

Clinically, PV blisters are fragile and rupture easily, leaving painful erosions, whereas other blistering diseases like bullous pemphigoid tend to have tense blisters that are less likely to rupture. The Nikolsky sign (skin shearing with lateral pressure) is often positive in PV but less so in other blistering disorders NICE CKS Melchionda & Harman 2019.

In primary care, a thorough history and examination focusing on the presence of oral erosions, the nature of the blisters (flaccid vs tense), and the Nikolsky sign can guide suspicion towards PV. Definitive diagnosis requires referral for specialist assessment including skin biopsy for histology and direct immunofluorescence, which are not available in primary care NICE CKS Guillen & Khachemoune 2007Melchionda & Harman 2019.

Other blistering disorders to consider include bullous pemphigoid, dermatitis herpetiformis, and linear IgA disease, which differ in typical patient age, blister characteristics, and mucosal involvement. For example, bullous pemphigoid usually affects older adults and presents with tense blisters without mucosal involvement initially, while dermatitis herpetiformis is intensely itchy and associated with gluten sensitivity NICE CKS.

In summary, in primary care, the key differentiators for pemphigus vulgaris are the presence of painful oral erosions, flaccid blisters that rupture easily, and a positive Nikolsky sign, prompting urgent specialist referral for confirmation and management. Early recognition is critical due to the potential severity of PV NICE CKS Guillen & Khachemoune 2007Melchionda & Harman 2019.