Which two conditions are known to present as complete vesicles?

The correct answer highlights pemphigus and herpes simplex as conditions that manifest with complete vesicles. Pemphigus is an autoimmune disorder characterized by the presence of blisters or vesicles on the skin and mucous membranes, resulting from the destruction of desmosomes that hold epithelial cells together. In this condition, the vesicles typically rupture, creating painful erosions, but initially appear as intact fluid-filled blisters.

Herpes simplex, on the other hand, is caused by a viral infection and also presents with vesicles. These vesicles are often grouped together and are filled with clear fluid. They can occur on various mucosal sites, such as the lips and oral cavity, and are typically painful.

In contrast, aphthous ulcers are painful, shallow ulcers rather than blisters. They present as localized lesions with a distinct border and often have a whitish or gray center, not vesicles. Erythema migrans, associated with Lyme disease, does not present in vesicle form but rather as a characteristic expanding red rash, commonly in a "bull's-eye" appearance.

Understanding the differentiation between these conditions is crucial for accurate diagnosis and treatment in clinical practice.