Erythema multiforme/EM is a skin condition characterized by hyper-reaction of very sensitive skin to primarily an underlying case of herpes simplex viral infection which results in the formation of abnormal skin lesions. EM also tends to affect the mucous membranes.
Erythema multiforme is categorized into major and minor forms. It can affect people of all age groups, all races, and both genders. However, adults aged between 20 and 40 years are more prone to developing EM than others. People with certain genetic disorders are at increased risk and more likely to suffer from frequent episodes of erythema multiforme. Certain tissue types are more prevalent in people with herpes infection; hence such people are at increased risk to developing EM.
Erythema multiforme is different from other skin conditions like TEN/Toxic Epidermal Necrolysis or Stevens Johnson syndrome/SJS, which are also marked by hypersensitive skin reactions. EM is a serious disorder, but is often self-limiting and usually clears out without resulting in any abnormal health problems.
Symptoms of erythema multiforme
Erythema multiforme minor usually does not cause any prodromal symptoms, while EM major may result in mild prodromal symptoms like joint pain, fever, chills, and overall weakness.
Some of the common signs and symptoms associated with erythema multiforme are listed below.
1. Skin Problems
- Doctors can determine the stage of lesion formation only after a complete examination of the skin.
- Skin lesions may form in less than 24 hours after the development of erythema multiforme. Initially, the lesions appear on the back of the hands and the top of the feet. They then migrate to other parts of the body. Commonly affected regions include the face, trunk, neck, elbows, and knees.
- Patients may suffer from itchiness and burning sensations.
- Initially, the lesions are red or pink colored, flat, solitary skin abnormalities. They gradually become swollen and turn into larger raised papules. The lesions may eventually become clusters of plaque with a pigmented center and a tendency to blister and scab over.
- The lesions of erythema multiforme are typically rounded with clear outlines and three concentric areas. The center has a dark red hue along with crusting and blistering. The next concentric region is pink, swollen, and full of fluid deposits. The outermost concentric part is bright red in color.
- In rare cases, erythema multiforme lesions may feature just two affected parts with no distinctive borders.
- Sometimes, the rash may not elicit any swelling or inflammation. However, patients with EM major may suffer from swelling of the lips.
2. Mucous Membranes
- EM lesions of the mucous membranes generally form a few days after the appearance of the skin lesions.
- Mucous membrane lesions may be asymptomatic or mild in people with erythema multiforme minor.
- Initially, patients may suffer from elevated redness of the lips and the inside wall of the cheeks. Occasionally, blisters may form in the oral cavity, rupture, and become ulcers. Presence of swollen lips and bloody crusting can then lead to speaking and swallowing difficulties.
- Some of the mucous membranes commonly affected by EM major include the eyes, bronchi/trachea, anus or genitals, gastrointestinal tract, tongue, inside wall of the cheeks, and lips. Uncommonly, the palate, gums, and base of the mouth may also develop the lesions.
- Other affected mucous membranes also feature swelling, redness, and blister formation, which may eventually burst and result in painful shallow ulcers. These ulcers are enclosed in whitish pseudomembrane.
- Mycoplasma pneumonia is isolated to the mucous membranes. Patients with severe instances of mycoplasma pneumonia may need to be hospitalized.
Causes of erythema multiforme
- Erythema multiforme is caused due to infections. Infection by the herpes simplex virus is regarded as the most widespread cause. EM occurs 3 to 14 days after infection by the herpes virus.
- In most cases, EM is triggered by herpes labialis infection, while sometimes it may occur due to genital herpes. HSV type 1 infection poses greater risk than HSV type 2 infections.
- EM may also be caused due to infections by herpes varicella zoster virus, hepatitis viruses, HIV, cytomegalovirus, adenovirus, par poxvirus, and viral vaccines.
- Other causative triggers of erythema multiforme include mycoplasma pneumonia infection and reaction to varied drugs like phenothiazines, barbiturates, sulphonamides, NSAIDs, penicillin, and anticonvulsants.
- Erythema multiforme may occur many times in a year and a patient may suffer from numerous EM episodes for several years. The main cause of such recurring bouts of EM lesions is thought to be HSV-1 infection.
Most cases of erythema multiforme lesions disappear on their own without any medical treatment. A few common treatment options are listed below:
- HSV infections can be treated with acyclovir pills. Mycoplasma pneumonia is treated with antibiotics.
- Local anesthetics and antiseptic mouth washes can help ease oral infection and pain.
- Eye disorders need to be checked and treated by an eye doctor.
- Itchiness can be alleviated with antihistamine pills and topical corticosteroids.
- Swallowing and drinking difficulties and subsequent health problems need treatment at a hospital.