Which sign would you expect to be positive in a patient suffering from pemphigus vulgaris?

In patients with pemphigus vulgaris, a positive Nikolsky's sign is expected. Pemphigus vulgaris is an autoimmune blistering disorder characterized by the formation of painful blisters on the skin and mucous membranes, stemming from the loss of adhesion between keratinocytes due to the presence of autoantibodies against desmogleins.

The Nikolsky's sign is tested by applying gentle lateral pressure to the skin, and in patients with pemphigus vulgaris, the epidermis easily separates, leading to blister formation. This phenomenon indicates a fragility of the skin which is a hallmark of the disease, confirming the diagnosis.

Other tests mentioned, such as Tinel's, Homan's, and Murphy's signs, are not relevant to pemphigus vulgaris. Tinel's sign is associated with nerve injury, Homan's sign examines for deep vein thrombosis, and Murphy's sign relates to gallbladder disease. None of these signs reflect the underlying pathology or clinical manifestations of pemphigus vulgaris, making Nikolsky's sign the appropriate choice in this context.