The word Erythema is derived from the greek word erythros that means redness of the skin. It may occur with skin injury, infection or inflammation. Erythema disappears with finger pressure (blanching), while purpura or bleeding in the skin and pigmentation do not. There are few conditions that needs a short discription here:
1. Erythema Multiforme
Acute self limiting onset of symmetrical fixed red papules , some of which form target lesions. May blister. Can show koebner phenomenon. May involve lips, buccal mucosa, and tongue.
Causes: the causes of erythema multiforme includes:
- Infections like herpes simplex virus, mycoplasma, EBV, Chylamydiae
- Drugs like sulphonamides, penicillin
- Collagen diseases like SLE, polyarteritis nodosa
- Underlying malignancy
2. Steven- Johnson syndrome
Causes are same as for erythema multiforme. Other features include
- Severe erosions of at least two mucosal surfaces .
- Prodromal respiratory illness.
- Extensive necrosis of lips and mouth.
- Purulent conjunctivitis
- Variable skin involvement- red macules, bullae, skin necrosis and denudation.
3. Erythema nodosum
Nodular, erythematous eruption on extensor aspects of legs , less commonly on thighs and forearms. Regresses to bruises. May last for 3 to 6 weeks.
Causes: may include
- Infections ; organisms mostly involved are streptococcus, salmonella, yersinea, tuberculosis, chlamydia, EBV etc
- Gut disorders like ulcerative colitis and crohn’s disease
- Malignancy like leukemias and lymphomas
- Drugs e.g sulphonamides
4. Erythema Marginatum
Annular migratory erythema found in 10% of cases of rheumatic fever. Recurrent crops of lesions appear weekly. Associated with active cardiac disease.