Vesicular rash

A vesicular rash is a scattered or linear distribution of blisterlike lesions — sharply circumscribed and filled with clear, cloudy, or bloody fluid. The lesions, which are usually less than 0.5 cm in diameter, may occur singly or may occur in groups. (See Recognizing common skin lesions, page 467.) They sometimes occur with bullae — fluid-filled lesions that are larger than 0.5 cm in diameter.

A vesicular rash may be mild or severe and temporary or permanent. It can result from infection, inflammation, or allergic reactions.

History and physical examination

Ask your patient when the rash began, how it spread, and whether it has appeared before. Did other skin lesions precede eruption of the vesicles? Obtain a thorough drug history. If the patient has used a topical medication, what type did he use and when was it last applied? Also, ask about associated signs and symptoms. Find out if he has a family history of skin disorders, and ask about allergies, recent infections, insect bites, and exposure to allergens.

Examine the patient’s skin, noting if it’s dry, oily, or moist. Observe the general distribution of the lesions and record their exact location. Note the color, shape, and size of the lesions, and check for crusts, scales, scars, macules, papules, or wheals. Palpate the vesicles or bullae to determine if they’re flaccid or tense. Slide your finger across the skin to see if the outer layer of epidermis separates easily from the basal layer (Nikolsky’s sign).

Medical causes

Burns (second degree)

Thermal burns that affect the epidermis and part of the dermis cause vesicles and bullae, with erythema, swelling, pain, and moistness.

Dermatitis

With contact dermatitis, a hypersensitivity reaction produces an eruption of small vesicles surrounded by redness and marked edema. The vesicles may ooze, scale, and cause severe pruritus.

Dermatitis herpetiformis is a skin disease that’s most common in men between ages 20 and 50 (and is occasionally associated with celiac disease, organ malignancy, or immunoglobulin A immunotherapy) and produces a chronic inflammatory eruption marked by vesicular, papular, bullous, pustular, or erythematous lesions. Usually, the rash is symmetrically distributed on the buttocks, shoulders, extensor surfaces of the elbows and knees, and sometimes the face, scalp, and neck. Other symptoms include severe pruritus, burning, and stinging.

With nummular dermatitis, groups of pinpoint vesicles and papules appear on erythematous or pustular lesions that are nummular (coinlike) or annular (ringlike). Often, the pustular lesions ooze a purulent exudate, itch severely, and rapidly become crusted and scaly. Two or three lesions may develop on the hands, but the lesions typically develop on the extensor surfaces of the limbs and on the buttocks and posterior trunk.

Erythema multiforme

Erythema multiforme is an acute inflammatory skin disease that’s heralded by a sudden eruption of erythematous macules, papules and, occasionally, vesicles and bullae. The characteristic rash appears symmetrically over the hands, arms, feet, legs, face, and neck and tends to reappear. Although vesicles and bullae may also erupt on the eyes and genitalia, vesiculobullous lesions usually appear on the mucous membranes — especially the lips and buccal mucosa — where they rupture and ulcerate, producing a thick, yellow or white exudate. Bloody, painful crusts, a foul-smelling oral discharge, and difficulty chewing may develop. Lymphadenopathy may also occur.

Herpes simplex

Herpes simplex is a common viral infection that produces groups of vesicles on an inflamed base, most commonly on the lips and lower face. In about 25% of cases, the genital region is the site of involvement. Vesicles are preceded by itching, tingling, burning, or pain; develop singly or in groups; are 2 to 3 mm in size; and do not coalesce. Eventually, they rupture, forming a painful ulcer followed by a yellowish crust.

Herpes zoster

With herpes zoster, a vesicular rash is preceded by erythema and, occasionally, by a nodular skin eruption and unilateral, sharp, pain along a dermatome. About 5 days later, the lesions erupt and the pain becomes burning. Vesicles dry and scab about 10 days after eruption. Associated findings include fever, malaise, pruritus, and paresthesia or hyperesthesia of the involved area. Herpes zoster involving the cranial nerves produces facial palsy, hearing loss, dizziness, loss of taste, eye pain, and impaired vision.

Insect bites

With insect bites, vesicles appear on red hivelike papules and may become hemorrhagic.

Pemphigoid (bullous)

Generalized pruritus or an urticarial or eczematous eruption may precede pemphigoid — a classic bullous rash. Bullae are large, thick-walled, tense, and irregular, typically forming on an erythematous base. They usually appear on the lower abdomen, groin, inner thighs, and forearms.

Pompholyx (dyshidrosis or dyshidrosis eczema)

Pompholyx is a common, recurrent disorder that produces symmetrical vesicular lesions that can become pustular. The pruritic lesions are more common on the palms than on the soles and may be accompanied by minimal erythema.

Porphyria cutanea tarda

Bullae — especially on areas exposed to sun, friction, trauma, or heat — result from abnormal porphyrin metabolism. Photosensitivity is also a common sign. Papulovesicular lesions evolving into erosions or ulcers and scars may appear. Chronic skin changes include hyperpigmentation or hypopigmentation, hypertrichosis, and sclerodermoid lesions. Urine is pink to brown.

Scabies

Small vesicles erupt on an erythematous base and may be at the end of a threadlike burrow. Burrows are a few millimeters long, with a swollen nodule or red papule that contains the mite. Pustules and excoriations may also occur. Men may develop burrows on the glans, shaft, and scrotum; women may develop burrows on the nipples. Both sexes may develop burrows on the webs of the fingers, wrists, elbows, axillae, and waistline. Associated pruritus worsens with inactivity and warmth and at night.

Smallpox

(variola major). Initial signs and symptoms of smallpox include high fever, malaise, prostration, severe headache, backache, and abdominal pain. A maculopapular rash develops on the mucosa of the mouth, pharynx, face and forearms and then spreads to the trunk and legs. Within 2 days the rash becomes vesicular and later pustular. The lesions develop at the same time, appear identical, and are more prominent on the face and extremities. The pustules are round, firm, and deeply embedded in the skin. After 8 to 9 days, the pustules form a crust. Later, the scab separates from the skin, leaving a pitted scar. In fatal cases, death results from encephalitis, extensive bleeding, or secondary infection.

Tinea pedis

Tinea pedis is a fungal infection that causes vesicles and scaling between the toes and, possibly, scaling over the entire sole. Severe infection causes inflammation, pruritus, and difficulty walking.

Toxic epidermal necrolysis

Toxic epidermal necrolysis is an immune reaction to drugs or other toxins, in which vesicles and bullae are preceded by a diffuse, erythematous rash and followed by large-scale epidermal necrolysis and desquamation. Large, flaccid bullae develop after mucous membrane inflammation, a burning sensation in the conjunctivae, malaise, fever, and generalized skin tenderness. The bullae rupture easily, exposing extensive areas of denuded skin. (See Drugs that cause toxic epidermal necrolysis.)

Special considerations

Any skin eruption that covers a large area may cause substantial fluid loss through the vesicles, bullae, or other weeping lesions. If necessary, start an I.V. line to replace fluids and electrolytes. Keep the patient’s environment warm and free from drafts, cover him with sheets or blankets as necessary, and take his rectal temperature every 4 hours because increased fluid loss and increased blood flow to inflamed skin may lead to hyperthermia.

Obtain cultures to determine the standard causative organism. Use precautions until infection is ruled out. Tell the patient to wash his hands often and not to touch the lesions. Be alert for signs of secondary infection. Give the patient an antibiotic, and apply corticosteroid or antimicrobial ointment to the lesions.

Pediatric pointers

Vesicular rashes in children are caused by staphylococcal infections (staphylococcal scalded skin syndrome is a life-threatening infection occurring in infants), varicella, hand-foot-and-mouth disease, contact dermatitis, and miliaria rubra.

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Book Source Details

• Book Title: Handbook of Signs & Symptoms (Third Edition)
• Author(s): Springhouse
• Year of Publication: 2006
• Copyright Details: Handbook of Signs & Symptoms (Third Edition), Copyright © 2006 Lippincott Williams & Wilkins.

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