2. Introduction
Lepra reactions comprise several common
immunologically inflammatory states that can
cause considerable morbidity.
Some of these reactions precede diagnosis and
institution of effective antimicrobial therapy.
Other reactions occur after the initiation of
appropriate chemotherapy.
3. Types
Lepra Reaction are of two types :
1. Type 1 Lepra Reactions :
(Downgrading and Reversal Reactions)
2. Type 2 Lepra Reactions :
Erythema Nodosum Leprosum (ENL)
4. Type 1 Lepra Reactions :
It is delayed type of hypersensitivity.
Occur in patients with borderline forms of leprosy .
Classic signs of inflammation within previously
involved macules,papules and plaques,which are
markedly erythematous, swollen and oedematous.
Mainly involves the trunk.
Occasionally,there is appearance of new skin
lesions,neuritis and fever (low-grade).
Associated with large numbers of T cells bearing
receptors – a unique feature of leprosy.
5. Contd..
Cutaneous lesions ,which are markedly
erythematous, swollen and oedematous with
sharp margins are common.
Desquamation and ulceration of lesions may occur.
Nerve trunk involvement is also common .
Ulnar nerve involvement at the elbow (most
common), painful and exquisitely tender, results in
clawing of hand.
Wrist drop due to radial nerve involvement.
Footdrop occurs when peroneal nerve is involved.
Facial palsy may also be associated .
Edema is the most characteristic microscopic feature.
7. Facial Palsy and claw hand
in Type 1 Lepra Reaction
A)Claw Hand with ulceration
of palmar surface.
A)Loss of longitudinal arch
with flat/boat shaped foot
9. Contd..
Downgrading Reactions :
When type 1 lepra reactions precede the initiation of
appropriate antimicrobial therapy.
Histologically , more lepromatous .
Loss of focalization and tubercle formation.
Decrease in number of lymphocytes.
Epithelioid cells co-differentiate towards simple histiocytes
and may show intracellular oedema.
Bacillary multiplication & rising morphological index.
Extracellular oedema.
10. Contd.
Reversal Reactions :
Occur after the initiation of antimicrobial therapy.
Histologically,more tuberculoid.
Oedema and increase in lymphocytic infiltration & volume.
Macrophage differentiation towardsepitheloid cells and giant
cells take appearance of Langhan’s cells.
Occasionally,necrosis with in the granuloma.
Increased number of bacilli & morphological index falls.
Occur in the first months or years after the initiation of
therapy.
Typified by TH 1 cytokine profile,with an influx of CD4+ T
helper cells and increased levels of IFN- and IL-2.
11. Type 2 Lepra Reactions :
Erythema nodosum leprosum (ENL) occurs
exclusively in patients near the lepromatous end of
the leprosy spectrum (BL-LL) and is more severe.
It is Type III hypresensitivity reaction.
30 % of all lepromatous cases have at least one attack
of ENL.
90 % of cases follow the institution of chemotherapy,
generally within 2 years .
May precede diagnosis and initiation of therapy .
Dome-shaped lesions with ill-defined margins .
12. Contd.
Associated with elevated levels of circulating tumor
necrosis factor (TNF),TH2 cytokine profile and high
levels of IL-6 and IL-8.
Hence,thought to be a cause of immune complex
deposition due to the antigen from the dying bacilli.
Histologically,
Focus of inflammation is away from the major skin
lesions,deep in the dermis.
Polymorph infiltration,oedema & cellular disintegration.
Few bacilli at centre of reaction site (More if severe).
Vascular necrosis with haemorrhage and ulceration.
13. Contd.
Most common features are :
Crops of painful,swollen,tender,erythematous,
shiny papules (resolve in a few days to a week but
may recur), sitting on the skin or involving deep
dermis mainly on the face and extremities with fever.
Malaise
Symptoms of neuritis ,uveitis, orchitis ,
lymphadenitis , glomerulonephritis .
Anemia .
Leukocytosis .
Abnormal liver function tests (increased
aminotransferase levels).
Arthiritis and Iridocyclitis.
16. Contd.
Patients may have a single bout of ENL or chronic
recurrent manifestations.
Bouts may be mild or severe and generalized & may
rarely cause death.
Skin biopsy reveals vasculitis or panniculitis
characteristically with polymorphonuclear
leukocytes and sometimes with lymphocytes.
Presence of HLA-DR framework antigen of
epidermal cells (marker of delayed hypersensitivity).
Higher levels of IL-2 and IFN- is usually seen in
polar lepromatous disease.
17. Lucio’s Phenomenon :
Unusual reaction seen exclusively in patients
from the Caribbean and Mexico having
diffuse lepromatous form of lepromatous
leprosy,who are left untreated.
Patient develops recurrent crops of
large,sharply marginated,ulcerative lesions
(lower extremities).
May be generalized and fatal as a result of
secondary infection and consequent septic
bacteremia.
18. Contd.
Histologically,
Ischemic necrosis of the epidermis and superficial
dermis.
Heavy parasitism of endothelial cells with AFB.
Endothelial proliferation and thrombus formation
in large vessels of the deeper dermis.
Probably,mediated by immune complexes
(like ENL).
19. b) Histology of
a) Lesions on buttocks and thighs Lucio’s Phenomenon
in Lucio’s Phenomenon
