Tzanck Test, Nikolsky Sign, and Bulla Spread Sign

Understanding Nikolsky Sign

The Nikolsky sign is a clinical dermatological finding where gentle pressure or lateral traction on the skin causes detachment of the epidermis. This sign is crucial in diagnosing certain blistering skin diseases.

Conditions where Nikolsky Sign is Positive

Pemphigus Vulgaris: An autoimmune condition leading to intraepidermal blistering due to desmosome disruption.
Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN): Severe mucocutaneous reactions characterized by widespread epidermal necrosis.
Staphylococcal Scalded Skin Syndrome (SSSS): Caused by Staphylococcus aureus toxins leading to epidermal splitting.

Conditions where Nikolsky Sign is Negative

Bullous Pemphigoid: Unlike pemphigus, this subepidermal blistering disorder shows a negative Nikolsky sign due to intact basement membrane adhesion.
Dermatitis Herpetiformis: A chronic blistering disease associated with gluten sensitivity, demonstrating non-fragile vesicles.