Erythema Multiforme

ETIOLOGY:

• Idiopathic: Most common cause
• Viral : HSV (most important) HBV, Mumps, Adenovirus
• Bacteria :Streptococci, tuberculosis, M. pneumoniae
• Fungal : Coccidioidomycosis, Histoplasmosis.
• Drugs -: Antibiotics (Sulphonamide), Phenytoin, NSAIDS.
• Autoimmune disease: SLE, thyroiditis, RA
• Others: Sarcoidosis, Pregnancy, Malignancy.

CLASSIFICATION :

• Erythema multiforme major-typical targets or raised, edematous papules distributed acrally
• Erythema multiforme minor-typical targets or raised, edematous papules distributed acrally with involvement of one or more mucous membranes; epidermal detachment involves less than 10% of total body surface area (TBSA)
• Toxic epidermal necrolysis
• Stevens–Johnson syndrome-widespread blisters predominant on the trunk and face, presenting with erythematous or pruritic macules and one or more mucous membrane erosions; epidermal detachment is less than 10% TBSA for Stevens-Johnson syndrome and 30% or more for toxic epidermal necrolysis.

CLINICAL FEATURES:

Prodromal Features :

• Prev Attack (30%) 
• Preceding Infection Fever (T>103.1 deg C)
• Cutaneous Lesions 
• Mucous Lesions 

CUTANEOUS LESIONS :

•  Symmetrical, Acral, Centripetal Rash
• Hemorrhagic crusts
• Extensor aspect : Extremities > Face > Neck > Trunk
• Predilection to Sun-Exposed Areas / Koebnerization 
• Well-defined, circular, blanching papule / plaque that persists for 01 week – Self-limiting in 04 weeks – Persistent / Continuous EM 

 Typical Target Lesion

•  Dusky Central Disk / Bulla (later Violaceous / Purpuric) 
• Infiltrated Pale Ring 
•  Erythematous edematous halo Larger lesions show Central Bulla and Marginal ring of vesicles , Herpes Iris of Bateman
• vesicles, ruptured to form ulcers covered with pseudomembrane

 Raised Atypical Target lesions / Targetoid lesions

• SJS-TEN lesions – mostly Macular MUCOSAL LESIONS 
• 70% Cases 
• Lips – Cutaneous Target Lesions Serous Crusting 

MUCOSAL LESIONS :

•  LIPS – Mucosal (Erosions / Vesicles / Bullae) 
• GINGIVAL / Ventral Tongue
• Hard Palate – Spared 
•  Pharynx / Larynx / Trachea / Bronchi
• Conjunctivitis B/L with Vesicles / Erosions 
• Nasal / Urethral / Anal Mucosae 
• 2/3 Mucosal Sites sans Cutaneous inv – FUCH’s SYNDROME

TREATMENT:

• Treating underlying Etiology 
• Reducing morbidity – Oral CS
• Anti-Virals 
•  Macrolides / Quinolones for MPAEM 
• Oral EM – Topical CS / Anesthetics / Antacids 

RECURRENT EM 

• Anti-Virals 
• Topical Acyclovir 
•  Azathioprine 
• Thalidomide