Erythema

CLINICAL DIAGNOSTIC MANUAL

Erythema is the redness of the skin resulting from the dilation of superficial blood vessels. This redness can be localized or generalized and is associated with various conditions that may be inflammatory, infectious, allergic, autoimmune, or caused by physical damage. Accurate identification of the cause of erythema is essential for proper management and may require a combination of medical history, physical examination, and complementary tests.

Pathology	Suspected Diagnosis	Confirmatory Diagnosis
Cellulitis	Redness, pain, warmth, and swelling of the skin, fever.	Skin culture, blood culture, blood tests showing leukocytosis.
Gout	Redness and severe pain in a joint, usually the big toe.	Synovial fluid analysis, elevated uric acid levels in blood.
Thermal burn	History of heat exposure, redness, blisters.	Physical examination, medical history.
Chemical burn	History of chemical exposure, redness, pain, blisters.	Physical examination, medical history.
Sunburn	History of sun exposure, redness, blisters.	Physical examination, medical history.
Drug eruption	History of drug intake, redness, skin rash.	Physical examination, medical history, allergy tests.
Drug allergy rash	History of drug intake, redness, skin rash.	Physical examination, medical history, allergy tests.
Viral toxic erythema	Fever, general malaise, skin rash.	Physical examination, serological tests for viral infections.
Rosacea	Persistent facial redness, telangiectasias, papules, and pustules.	Physical examination, medical history.
Palmar erythema	Redness of the palms, associated with liver diseases.	Physical examination, liver function tests.
Photosensitivity caused by drugs	History of drug intake, redness after sun exposure.	Physical examination, medical history, photosensitivity tests.
Erythema multiforme due to sarcoidosis	Target-like lesions, fever, general malaise.	Skin biopsy, chest X-ray, serological tests.
Systemic lupus erythematosus	Malar rash, photosensitivity, arthritis, fever, fatigue.	Serological tests, ANA, anti-dsDNA, skin biopsy.
Erythema ab igne	Reticulated redness in areas exposed to prolonged heat.	Physical examination, medical history.
Livedo reticularis	Reticulated redness, usually on the legs.	Physical examination, serological tests, imaging studies.
HIV seroconversion	Fever, skin rash, general malaise.	Serological tests for HIV.
Erythema nodosum	Painful nodules on the legs, fever, general malaise.	Skin biopsy, serological tests, tuberculosis tests.
Erythema induratum	Painful nodules on the legs associated with tuberculosis infection.	Skin biopsy, tuberculosis tests.
Erythema chronicum migrans	Bull’s-eye lesion, history of tick bite.	Physical examination, serological tests for Lyme disease.