43: Erythema Multiforme

Question 1

What is Erythema Multiforme (EM) and how is it classified?

Answer 1

Erythema Multiforme (EM) is an acute mucocutaneous syndrome characterized by distinctive clinical patterns that are mild and self-limited, with a risk of relapse. It is classified into two categories based on mucous membrane involvement: EM minor (EMm), which involves only skin and lips, and EM major (EMM), which involves mucous membranes.

Question 2

What are the epidemiological characteristics of Erythema Multiforme?

Answer 2

Erythema Multiforme (EM) is common with an unknown true incidence. EM minor (EMm) is more common than EM major (EMM), prevalent in adolescents and young adults, with a male-to-female ratio of approximately 2:3. Recurrence rates are 10% for EMM and 30% for EMm, particularly in HSV-associated cases.

Question 3

What are the clinical features and history associated with Erythema Multiforme?

Answer 3

Most cases of Erythema Multiforme (EM) have no prodromal symptoms; if present, they are mild. In EMM, fever may exceed 38.5°C in about 1/3 of cases. A review of events in the preceding 3 weeks should look for signs of HSV or respiratory infections.

Question 4

What are the cutaneous features of Erythema Multiforme?

Answer 4

The cutaneous features of Erythema Multiforme (EM) include abrupt eruption of lesions, mostly symmetric distribution, centripetal spread, and a predilection for sun-exposed sites. Lesions are often asymptomatic, with occasional burning and itching.

Question 5

What subtype of EM involves only the skin and lips?

Answer 5

This represents EM minor (EMm), where only the skin and lips are involved.

Question 6

What is the preferred term for lesions that involve mucous membranes?

Answer 6

The preferred term for this presentation is mucosal erythema multiforme (EMM).

Question 7

What subtype of EM involves typical targets on the extremities?

Answer 7

This represents typical erythema multiforme major (EMM), which involves typical targets on the extremities.

Question 8

What is the typical distribution pattern of EM lesions?

Answer 8

EM lesions are often symmetric and appear on extensor surfaces (hands, feet, elbows, knees), face, and neck, with a predilection for sun-exposed sites.

Question 9

What subtype of EM is associated with Mycoplasma pneumoniae?

Answer 9

This is atypical erythema multiforme (EMM), which is more frequently associated with Mycoplasma pneumoniae.

Question 10

What is the average interval between HSV infection and the onset of EM lesions?

Answer 10

The average interval between HSV infection and the onset of EM lesions is 7 days, with a range of 2-17 days.

Question 11

What is the typical time frame for the appearance of EM lesions?

Answer 11

EM lesions typically appear abruptly, with most patients developing all lesions within 3 days.

Question 12

What phenomenon explains the distribution of EM lesions?

Answer 12

The distribution of EM lesions is explained by the Koebner phenomenon and their predilection for sun-exposed sites.

Question 13

What distinguishes Erythema Multiforme minor (EMm) from Erythema Multiforme major (EMM)?

Answer 13

EMm involves only the skin and lips, while EMM affects mucous membranes as well. EMm is characterized by a milder clinical pattern, whereas EMM presents with more severe symptoms due to mucosal involvement.

Question 14

What is the significance of the association between herpes simplex virus (HSV) and recurrent Erythema Multiforme?

Answer 14

In over 70% of recurrent Erythema Multiforme cases, an episode of recurrent HSV infection precedes the lesions, suggesting a strong link between HSV and the exacerbation of EM.

Question 15

How does Atypical Erythema Multiforme differ from Typical Erythema Multiforme?

Answer 15

Atypical Erythema Multiforme presents with more extensive and larger targets, often involving the skin around the mouth and eyes, while Typical Erythema Multiforme typically targets the extremities.

Question 16

What are the common cutaneous features observed in patients with Erythema Multiforme?

Answer 16

Common cutaneous features include abrupt eruption of lesions, symmetric distribution, centripetal spread, Koebner phenomenon, and an asymptomatic nature.

Question 17

What factors contribute to the epidemiology of Erythema Multiforme?

Answer 17

Erythema Multiforme is most prevalent in adolescents and young adults, with a male-to-female ratio of approximately 2:3. Recurrence rates are higher in EMm compared to EMM.

Question 18

What are the typical characteristics of a target lesion in Erythema Multiforme?

Answer 18

Target lesions are highly regular, circular, wheal-like erythematous papules or plaques that persist for 1 week or longer, with a size range of few mm to 3 cm.

Question 19

What noncutaneous features are commonly associated with Erythema Multiforme?

Answer 19

Mucosal lesions occur in 70% of patients, often limited to the oral cavity, with a predilection for lips and nonattached gingivae.

Question 20

What are the common complications associated with Erythema Multiforme?

Answer 20

Complications include impaired alimentation and reflex anuria, though severe ocular lesions are rare.

Question 21

What is the primary etiology and pathogenesis of Erythema Multiforme?

Answer 21

Most cases are related to infection, primarily HSV in recurrent cases, with M. pneumoniae as the second major cause.

Question 22

What diagnostic methods are used for confirming Erythema Multiforme related to M. pneumoniae?

Answer 22

PCR of throat swabs/bronchopulmonary lavage is the most sensitive for confirmation. Serology is diagnostic in the presence of IgM or IgA antibodies.

Question 23

How long do target lesions in Erythema Multiforme typically persist?

Answer 23

These lesions typically persist for 1 week or longer.

Question 24

What is the size range of infiltrated papules in Erythema Multiforme?

Answer 24

The size range of these lesions is a few millimeters to 3 cm.

Question 25

What is the most likely diagnosis for a patient with circular lesions and a dusky central disk?

Answer 25

The most likely diagnosis is erythema multiforme (EM) with typical target lesions.

Question 26

What is the likely cause of erythema multiforme in a patient with fever and oral erosions?

Answer 26

The likely cause is Mycoplasma pneumoniae-associated erythema multiforme (EM), more frequent in children and adolescents.

Question 27

What diagnostic tests can confirm the association with M. pneumoniae?

Answer 27

PCR of throat swabs or bronchopulmonary lavage is the most sensitive test, along with serology showing IgM or IgA antibodies.

Question 28

What is the most common infectious cause of EM in children?

Answer 28

The most common infectious cause of EM in children is Mycoplasma pneumoniae.

Question 29

Why is a true association between drugs and EM considered unlikely?

Answer 29

A true association between drugs and EM is unlikely because most cases attributed to drugs are actually EM imitators.

Question 30

What is the term for lesions that include a central bulla and a marginal ring of vesicles?

Answer 30

This specific lesion type is called the 'Herpes Iris of Bateman.'

Question 31

How do EM lesions differentiate from SJS or TEN?

Answer 31

EM lesions are infiltrated papules, whereas SJS/TEN lesions are macules.

Question 32

What is the likely cause of urinary retention in a patient with genital erosions?

Answer 32

The likely cause of urinary retention is pain from the genital erosions, leading to reflex urinary retention.

Question 33

What are the three concentric components of a typical target lesion?

Answer 33

The three concentric components are: 1) dusky central disk or blister, 2) infiltrated pale ring, and 3) erythematous halo.

Question 34

What areas are typically spared in mucosal involvement of EM?

Answer 34

The hard palate and attached gingivae are usually spared in mucosal involvement of EM.

Question 35

What percentage of patients with Erythema Multiforme (EM) experience mucosal lesions?

Answer 35

Mucosal lesions occur in 70% of patients, often limited to the oral cavity.

Question 36

What areas are commonly affected by Erythema Multiforme (EM)?

Answer 36

There is a predilection for lips (both cutaneous and mucosal sides), nonattached gingivae, and ventral tongue.

Question 37

Which areas are usually spared in Erythema Multiforme (EM)?

Answer 37

Hard palate and attached gingivae are usually spared.

Question 38

What clinical features may be present in Erythema Multiforme (EM)?

Answer 38

Erosions, fibrinous deposits, and occasional intact vesicles and bullae may be present.

Question 39

How does Erythema Multiforme (EM) affect the throat and respiratory tract?

Answer 39

It rarely affects the throat, larynx, trachea, and bronchi.

Question 40

What ocular symptoms may occur in children with Erythema Multiforme (EM)?

Answer 40

Eyes may show pain and bilateral conjunctivitis, especially in children with M. pneumoniae-associated EM.

Question 41

What complications are associated with Erythema Multiforme (EM)?

Answer 41

Complications include impaired alimentation due to painful mouth erosions and rare reflex anuria and severe ocular lesions.

Question 42

What is the primary etiology of Erythema Multiforme (EM)?

Answer 42

Most cases are related to infection, primarily HSV, especially in recurrent cases.

Question 43

How soon do Erythema Multiforme (EM) eruptions typically begin after HSV eruptions?

Answer 43

EM eruptions typically begin 7 days after HSV eruptions.

Question 44

What is the second major cause of Erythema Multiforme (EM) in children?

Answer 44

M. pneumoniae is the second major cause, particularly in children.

Question 45

What are the common conditions associated with Erythema Multiforme (EM)?

Answer 45

Conditions commonly associated with EM include Herpes simplex virus, Mycoplasma pneumoniae, Epstein-Barr virus, Orf, Parvovirus B19, Hepatitis B, and Hepatitis C.

Question 46

What is the typical course of Erythema Multiforme (EM)?

Answer 46

The course is mild, subsiding within 1-4 weeks, with complete recovery expected.

Question 47

What is the mean number of attacks per year for patients with Erythema Multiforme (EM)?

Answer 47

The mean number of attacks is 6 per year (range 2-36).

Question 48

What is the typical duration of Erythema Multiforme (EM)?

Answer 48

The mean total duration is 6-9 years, with 33% of cases persisting for more than 10 years.

Question 49

What management strategies are recommended for Erythema Multiforme (EM)?

Answer 49

Management includes systemic corticosteroids, anti-HSV drugs (ineffective for established EM), symptomatic treatment for M. pneumoniae, topical treatments, ocular care, and amniotic membrane grafting for severe cases.

Question 50

What preventive measures can reduce recurrences of Erythema Multiforme (EM)?

Answer 50

Preventive measures include continuous therapy with oral anti-HSV drugs, topical acyclovir therapy (ineffective), and other treatments like azathioprine and thalidomide.

Question 51

What is the key histopathological feature in early Erythema Multiforme (EM)?

Answer 51

The key histopathological feature is lymphocytes at the dermoepidermal junction (DEJ) with exocytosis to the epidermis and satellite necrosis.

Question 52

What is the typical histopathological finding in advanced Erythema Multiforme (EM)?

Answer 52

In advanced EM, subepidermal blister formation and prominent melanophages are typical findings.

Question 53

What supportive treatments can be provided for painful mouth erosions in Erythema Multiforme (EM)?

Answer 53

Supportive treatments include liquid antacids, topical glucocorticoids, and local anesthetics.

Question 54

What preventive measures can help avoid residual eye scarring in Erythema Multiforme (EM)?

Answer 54

Ocular lubricants and topical steroids, as recommended by an ophthalmologist, can help prevent residual eye scarring.

Question 55

What alternative treatments could be considered for persistent Erythema Multiforme (EM)?

Answer 55

Alternative treatments include azathioprine, mycophenolate mofetil, or thalidomide.

Question 56

What diagnostic test should be performed for a patient with Erythema Multiforme (EM) presenting with fever and cough?

Answer 56

A chest X-ray and PCR assay for M. pneumoniae should be performed.

Question 57

What are the key clinical features suggesting a diagnosis of Erythema Multiforme (EM)?

Answer 57

Key features include lymphocytes at the DEJ, satellite necrosis, spongiosis, and absence of antidesmoplakin antibodies.

Question 58

What is the approach to a patient with Erythema Multiforme (EM) regarding hospitalization?

Answer 58

Assess if it is EM, determine hospitalization needs, and identify the probable cause.

Question 59

What are the differential diagnoses of Erythema Multiforme (EM)?

Answer 59

Differential diagnoses include Urticaria, Maculopapular drug eruption, Lupus erythematosus, Paraneoplastic pemphigus, Cicatricial pemphigoid, Antimicrobial EM major, Stevens-Johnson syndrome, and Sweet syndrome.

Question 60

What is Urticaria?

Answer 60

Annular, circinate, blanching erythema with transient lesions (individual lesions last <24h). ## Footnote More acute than EM.

Question 61

What characterizes Maculopapular drug eruption?

Answer 61

Widespread polymorphous, targetoid lesions, macules, and papules. Most often nonspecific. ## Footnote Rare (IP) and subacute.

Question 62

What is Lupus erythematosus ('Rowell syndrome')?

Answer 62

Characterized by lesions on the face and trunk with interface dermatitis. ## Footnote Possible (mouth) and subacute.

Question 63

What are the features of Paraneoplastic pemphigus?

Answer 63

Large targetoid lesions and annular plaques with a positive Nikolsky sign. ## Footnote Always tends to be severe, chronic.

Question 64

What is Cicatricial pemphigoid?

Answer 64

Bullae and crusts in different stages with subepidermal blister and positive DIF. ## Footnote Possible in BP (IP) in linear dermatosis, chronic for relapsing.

Question 65

What defines Antimicrobial 'EM major'?

Answer 65

Widespread small blisters with basal acantholysis and positive DIF. ## Footnote Contact, antibodies present, acute relapsing.

Question 66

What is Stevens-Johnson syndrome?

Answer 66

Widespread small blisters with atypical targets, typically confluent. ## Footnote Contact, acute.

Question 67

What characterizes Sweet syndrome (acute febrile neutrophilic dermatosis)?

Answer 67

Erythematous papules and succulent plaques with spongiosis and subcorneal vesicles. ## Footnote Rare, neutrophilia, acute.

Question 68

What is the first step in diagnosing suspected Erythema Multiforme (EM)?

Answer 68

Initial assessment to determine if the patient has transient lesions, widespread erythema, mucous membrane erosions, or blisters.

Question 69

What to do if uncertain about EM diagnosis?

Answer 69

Consider a biopsy for immunofluorescence and serum antibodies.

Question 70

How to assess the need for hospitalization in EM?

Answer 70

Assess if hospitalization is required based on the patient's condition.

Question 71

What to investigate as a probable cause of EM?

Answer 71

Check for a history of recurrent herpes, or consider Mycoplasma pneumoniae-related EM if there's a cough or upper respiratory tract infection.

Question 72

What to consider for patients with frequent recurrences of EM?

Answer 72

Consider anti-HSV prophylaxis in the absence of clinical herpes.

Question 73

66% of EM patients have HLA-_____ allele.

Answer 73

DQB1∗0301

Question 74

Atypical EMM, with more extensive distribution of giant larger targets, occasionally involves the skin around the mouth and the eyes, resulting in _____ facies.

Answer 74

clown-like

Question 75

_____ age and _____ infection are infrequent association with atypical EMM.

Answer 75

younger Mycoplasma pneumoniae

Question 76

Highest incidence of EM was found in _____ and _____.

Answer 76

male children young adults

Question 77

Recurrence happens in about _____% of patients with EMM and up to _____% in EMm, more frequently, but not exclusively, in _____-associated cases.

Answer 77

10% 30% HSV