Differential Diagnosis for Large, Firm, Fluid-Filled Blisters and Negative Nikolsky Sign
- Single Most Likely Diagnosis
- Bullous Pemphigoid: This is a common cause of large, firm, fluid-filled blisters, especially in elderly patients. The negative Nikolsky sign helps to differentiate it from other conditions like pemphigus vulgaris, where the sign is typically positive.
- Other Likely Diagnoses
- Dermatitis Herpetiformis: Characterized by intensely itchy, blistering skin, this condition often presents with firm, fluid-filled blisters and a negative Nikolsky sign.
- Epidermolysis Bullosa Acquisita: An autoimmune condition that results in blistering of the skin, often with a negative Nikolsky sign, and can present with large, firm blisters.
- Do Not Miss Diagnoses
- Sjögren's Syndrome with Bullous Lesions: Although less common, Sjögren's syndrome can occasionally present with bullous lesions. Missing this diagnosis could lead to delayed treatment of the underlying autoimmune condition.
- Pseudoporphyria: A condition that can mimic porphyria cutanea tarda but is often associated with other medications or conditions. It's crucial not to miss this due to its potential for significant morbidity if not properly managed.
- Rare Diagnoses
- Acquired Bullous Epidermolysis: A rare condition with autoantibodies against type VII collagen, leading to subepidermal blisters.
- Linear IgA Bullous Dermatosis: Characterized by the presence of linear IgA deposits along the basement membrane zone, this condition can present with a variety of blistering patterns and is important to consider due to its potential for significant morbidity.