Diagnostic Hallmarks

Distribution: finger webs, elbows, axillary folds, buttocks, breasts, and penis

History of contagion: family members or sexual partners with evidence of similar disease

Identification of mites, feces, or ova in scrapings from lesions

Rapid response to therapy

Scabies is clearly a vesicular disease, but scratching, occasioned by the marked severity of itching, rapidly converts the process to one that is eczematous in character. Careful search may reveal a few intact linear vesicles (burrows), but they will never be apparent until you consider the correct diagnosis and then look.

More Vesicular Diseases

Hand, foot, and mouth disease is an infection in infants and children resulting from certain serotypes of Coxsackie A and B virus. It is characterized by the presence of a dozen or so small vesicles on the fingers, toes, palms, soles, and mucous membranes of the mouth. These vesicles are distinctive in their somewhat elongated, grayish appearance. Spontaneous resolution occurs in several days without sequelae.

Transient acantholytic dermatosis (Grover's disease) is a disease of unknown etiology characterized by the presence of small (2-3 mm) erythematous vesicopapules. These lesions are found scattered in a random fashion over the chest and back of middle-aged and older adults. Biopsy reveals a characteristic acantholytic pattern.

In pityriasis lichenoides of the acute type (Mucha-Habermann disease), some of the small (3-8-mm) erythematous papules may be capped with a small vesicle. These papules are randomly spread over the trunk and extremities. Hypopigmentation and small pitted scars are sometimes found at the site of healed lesions.

Insect bites, particularly those resulting from fleas, sometimes have a vesicle located at the summit of the inflammatory papule. The distribution (usually on the legs) and epidemiology generally suggest the correct diagnosis.

Small hemorrhagic vesicles are often seen in patients with neutrophilic vasculitis of the small vessel type. The lesions of gonococcemia are sometimes more vesicular than pustular. The papules of molluscum contagiosum are never vesicular, but their glistening, translucent appearance sometimes fools the unwary and accounts for the lay term, "water warts."