Blisters

CLINICAL DIAGNOSTIC MANUAL

Blisters are elevated, fluid-filled skin lesions that form when the skin is damaged. They can vary in size and are generally caused by friction, burns, infections, or autoimmune diseases. The fluid inside a blister may be clear, bloody, or purulent, depending on the underlying cause. Blisters are a protective response of the body to cushion the damaged skin and promote healing.

Pathology	Symptoms and Clinical Signs	Suspected Diagnosis	Confirmatory Diagnosis
Skin friction lesions	Small, painful blisters filled with clear fluid in areas of high friction like the feet and hands.	Medical history and physical examination.	Confirmation with medical history and physical examination.
Thermal burns	Large, painful blisters filled with clear or yellow fluid, accompanied by redness and pain in the surrounding skin.	History of heat exposure and physical examination.	Confirmation with medical history and physical examination.
Leg edema	Tense blisters filled with clear or yellowish fluid in edematous areas.	History of venous or lymphatic insufficiency, physical examination.	Confirmation with venous Doppler ultrasound and physical examination.
Chemical burns	Painful blisters filled with clear fluid, with redness and severe skin damage.	History of chemical exposure and physical examination.	Confirmation with medical history and physical examination.
Insect bites	Small, itchy blisters filled with clear fluid, surrounded by an inflamed area.	History of insect bite and physical examination.	Confirmation with medical history and physical examination.
Chickenpox	Itchy blisters filled with clear fluid that crust over, distributed across the body.	History of chickenpox contact and physical examination.	Confirmation with serology (IgM/IgG for varicella).
Herpes simplex	Painful blisters filled with clear fluid, usually on the lips or genitals.	Medical history and physical examination, PCR tests.	Confirmation with PCR for herpes simplex.
Herpes zoster	Painful blisters filled with clear fluid, grouped in a dermatomal pattern.	Medical history, history of chickenpox.	Confirmation with PCR for herpes zoster.
Herpetic whitlow	Painful blisters filled with clear fluid on the fingers, caused by the herpes virus.	Medical history and physical examination, PCR tests.	Confirmation with PCR for herpes simplex.
Hand, foot, and mouth disease	Small, painful blisters on hands, feet, and mouth, common in children.	Medical history and physical examination.	Confirmation with PCR for Coxsackie virus.
Dyshidrotic eczema	Itchy blisters filled with clear fluid on the palms and soles.	Medical history and physical examination.	Confirmation with skin biopsy and histopathological analysis.
Acute contact dermatitis	Itchy blisters filled with clear fluid in areas of contact with irritants.	Medical history and physical examination.	Confirmation with patch testing for allergens.
Pemphigus	Large, painful blisters filled with clear fluid that easily rupture.	Medical history and physical examination.	Confirmation with skin biopsy and direct immunofluorescence.
Bullous pemphigoid	Tense blisters filled with clear fluid on normal or red skin.	Medical history and physical examination.	Confirmation with skin biopsy and direct immunofluorescence.
Dermatitis herpetiformis (associated with gluten enteropathy)	Itchy blisters filled with clear fluid on elbows, knees, buttocks, and back.	Medical history and physical examination, serological tests for celiac disease.	Confirmation with skin biopsy and direct immunofluorescence.
Drug-induced bullous eruption	Large blisters filled with clear fluid, secondary to drug reaction.	Medical history and physical examination, medication review.	Confirmation with skin biopsy and histopathological analysis.
Erythema multiforme	Blisters and target lesions with a dark centre and lighter borders.	Medical history and physical examination.	Confirmation with skin biopsy and histopathological analysis.
Pemphigoid gestationis	Itchy blisters filled with clear fluid during pregnancy.	Medical history and physical examination, pregnancy history.	Confirmation with skin biopsy and direct immunofluorescence.
Porphyria	Blisters in sun-exposed areas, frequently on hands and face.	Medical history and physical examination, liver function tests.	Confirmation with urine porphyrin tests.
Toxic epidermal necrolysis	Large, painful blisters with widespread skin detachment.	Medical history, medication history.	Confirmation with skin biopsy and histopathological analysis.
Epidermolysis bullosa	Painful blisters from birth, caused by minimal friction.	Medical history and physical examination.	Confirmation with skin biopsy and genetic analysis.