Erythema multiforme is a condition that results as a reaction of hyper sensitive skin leading to the eruption of lesions. Such a reaction is mostly caused by herpes simplex virus infection. It may develop in mucous membranes and may be self-limiting and acute. Usually, it resolves without any complications.
Erythema multiforme is classified as major and minor types, and they are distinct from Toxic Epidermal Necrolysis (TEN) and Stevens Johnson syndrome (SJS). Though it can affect anyone without any race bias, individuals in the age group of 20 to 40, and predominantly males are affected.
There is a genetic inclination to EM, as certain tissue types are more likely to be found in individuals with herpes. For example: Recurrent EM (-DQB1*0301, HLA-B15, -A33, -B35, -DR53) and Associated EM (HLA-DQw3).
Symptoms of Erythema multiforme
For ED minor, usually there are no prodromal signs. But Erythema multiforme major may have mild symptoms such as chills and fever, general weakness or joint pains.
- Few or many lesions may erupt within 24 hours and they are first seen on the rear portions of hands and/or on tops of feet. The lesions then spread to other parts of the body. The neck, face and the trunk are the common affected areas, including the elbows and knees. The lesions may be associated with burning sensation and mild itching.
- In the initial stage the lesions are isolated, flat, round, red/pink that gradually enlarge and elevate to form plaques. Such papules may then develop into patches of plaques that darken in the center and develop crusting or blistering.
The general lesion of Erythema multiforme has round shape, sharp margins and three concentric color regions. They are:
- Dark red center with blister crust
- Next ring is light pinkish and elevated due to fluid swelling
- The third ring is bright red
Atypical lesions may show two zones with no distinct borders.
Full skin examination may be required to identify the stage of lesion development. The sites of rash may not have swelling. But in Erythema multiforme major, the lips may be swollen
Involvement of mucous membranes
- Mucosal lesions develop few days after the skin rash begins.
- In cases of EM minor, the involvement of mucous membrane is absent or mild. Initially mucosal changes consist of increased redness inside the cheek and of the lips. Sometimes blisters form, break and develop into ulcers.
In EM major, any of the below mentioned mucous membranes may be affected:
- Tongue, lips and inside the cheeks
- In rare cases, the palate, floor of the mouth and gums.
- Anus or the genitals
- The eyes
- The gastrointestinal tract
- The trachea/bronchi
Mucosal lesions usually have redness with blisters development and swelling. When blisters break, it makes painful, superficial ulcers covered by whitish pseudomembrane. Swollen lips with hemorrhagic crusts may cause difficulty in speaking and swallowing.
Mycoplasma pneumonia affects only the mucous membranes. When it is severe, the patient may need hospitalization.
Recurrence of EM:
- Erythema multiforme can recur many times in a year and it can repeat for many years. The HSV-1 infection is believed to the primary cause of the recurrence of Erythema multiforme.
Causes of Erythema multiforme
Infections: A majority of Erythema multiforme cases are associated with infections.
- Herpes simplex virus infection is the most common cause of developing Erythema multiforme. Usually herpes labialis and sometimes genital herpes trigger EM. The HSV type 1 is more associated than HSV type 2. The herpes infection occurs before the skin eruptions that develop within 3 to 14 days.
- Another most common cause for Erythema multiforme is Mycoplasma pneumonia, which is a lung condition caused by Mycoplasma pneumoniae.
The different types of virus infections that cause Erythema multiforme are:
- Hepatitis viruses
- Viral vaccines
- Human immunodeficiency virus
- Herpes varicella zoster
Dermatophyte fungal infections (tinea) are also known to result in Erythema multiforme.
Drugs: Less than 10% cases of EM may be caused as a reaction to medications.
- Many drugs such as barbiturates, NSAIDs, sulphonamides, penicillin, anticonvulsants and phenothiazines have been reported to cause Erythema multiforme.
Treatment of Erythema multiforme
In a majority of cases, treatment is not required as the condition resolves itself over many weeks without causing any medical complications.
The required treatments include oral acyclovir for HSV infection and antibiotics for Mycoplasma pneumonia. The symptoms associated with EM may be treated in the following ways:
- EM major may require hospitalization if it restricts drinking and swallowing activities.
- Local anesthetic and antiseptic mouth wash for oral pain and infection
- Topical corticosteroids or oral antihistamine to alleviate the itching
- Eye conditions should be treated by ophthalmologist.
Recurrent cases of Erythema multiforme are treated with oral acyclovir for 6 months. In case the intake of acyclovir is stopped, then the condition may occur again. Other antiviral drugs such as famciclovir and valciclovir can also be given if acyclovir does not help.
Other medications for suppressing the recurrence of EM are:
- Antimalarial drugs
- Thalidomide, mycophenolate mofetil, ciclosporin and photochemothrepy
Erythema multiforme pictures