This document provides information about Erythema Nodosum Leprosum (ENL), a type 2 reaction that occurs in patients with multibacillary leprosy with a heavy bacterial load. ENL is characterized by red, tender skin nodules and can involve multiple organs. It is caused by an Arthus-type allergic reaction when large numbers of killed leprosy bacteria release antigens. Diagnosis involves clinical presentation of skin and nerve inflammation as well as slit skin smears and histopathology. Treatment focuses on reassurance, continuing multidrug therapy, rest, NSAIDs for mild cases, and oral steroids for severe cases.

1. ERYTHEMA NODOSUM LEPROSUM
INTRODUCTION- Reactions occur due to abrupt change in immunological response of the body against
M. leprae.
Leprosy reaction can develop at anytime,
at Onset of the disease
before starting the treatment
During treatment
After completion of the treatment
Persons with following features are more likely to develop reactions:
 Multiple lesions
 Lesions close to the peripheral nerve (predisposes to neuritis)
 Lesions on the face
 People with nerve thickening with / without functional impairment (including thickening)
Reaction precipitating factors:
 Infections and infestations
 Vaccination
 Hormonal changes: Puberty, Pregnancy & Childbirth
 Psychological stress
TYPES OF REACTIONS
There are two types of Leprosy reactions.
(1) Type 1 Reaction: Also called Reversal Reaction can occur in any patient with unstable CMI
(2) Type 2 Reaction: Also called Erythema Nodosum Leprosum (ENL) occurs in patients with MB leprosy
having a heavy load of bacilli

2. TYPE 2 REACTIONS OR ENL (TYPE III HS)
Patients having high load of leprosy bacilli as in Multi- bacillary/ infiltrative type of leprosy get type 2
reaction.
Type-2 reaction can involve multiple organs & systems, causing generalized symptoms.
Cause: It occurs when large numbers of leprosy bacilli are killed, followed by release of their antigens.
These antigens from the dead bacilli provoke an arthus type allergic reaction
General condition: fever, headache and body ache
Skin lesions: Type 2 reactions exhibit the typical signs of erythema nodosum - red, firm, painful, tender
evanescent cutaneous and subcutaneous
Rarely they can break down and suppurate / necrose producing Erythema Nodosum Necroticans
(ulcerative ENL).
Inflammation of nerves: Nerves may also get affected in type 2 reactions.
Acute Neuritis: Existing involved or new nerves become enlarged, painful/tender and their sensory,
autonomic and motor functions get affected.

3. Silent neuropathy /quiet nerve paralysis: Sometimes, nerve function may get affected without any pain
or tenderness of the nerve or inflammation of skin lesions.
these patients need to be identified early and treated with corticosteroids.
Eyes-iritis , iridocyclitis
Nasal involvement- epistaxis
Orchitis
Arthritis
Swelling of hands and feet
Dactylitis
Glomerulonephritis
Rarely- hepatitis endocarditis

4. Diagnosis
1) Clinical-
Consider Reaction on
 Sudden appearance of symptoms
 Inflammation of existing skin lesions (type-1 reaction) or appearance of painful tender nodules (type-2
reaction)
 Inflammation of nerves
 Involvement of ocular tissue
 Swelling of hands, feet and pain in small joints
2) Slit skin smear
3) Histopathology
Treatment
1) reassurance
2) continue MBMDT
3) Bed rest
4) rest to affected nerve-splint may be required
5) NSAIDS in mild cases
6) oral steroids in severe cases
7)others - clofazimine, thalidomide can also be given