Type 2 lepra reaction is an example of which type of hypersensitivity reaction?
Please Remember
Type of Lepra Reaction + Type of Hypersensitivity Reaction = 5
Type 1 Lepra Reaction is Type IV Hypersensitivity Reaction ic Cell Mediated Immunity (1 +4 = 5)
Type II Lepra Reaction is Type III Hypersensitivity Reaction ie Immune Complexes (2 + 3 = 5)
Type I Lepra Reactions (Downgrading and Reversal Reactions)

Patients with borderline forms of leprosy hut not in patients with pure lepromatous disease.
It is Gell and Coombs type IV hypersensitivity reaction
Manifestations include classic signs of inflammation within previously involved macules, papules, and plaques and. on occasion, the appearance of new skin lesions, neuritis, and (less commonly j fever-—generally low-grade.
The nerve trunk most commonly involved in this process is the ulnar nerve at the elbow, which may be painful and exquisitely tender.
The most dramatic manifestation is foot dr op, which occurs when the peroneal nerve is involved.
When type 1 lepra reactions precede the initiation of appropriate antimicrobial therapy, they are termed downgrading reactions. and the case becomes histologically more lepromatous: when they occur after the initiation of therapy, they are termed reversal reactions, and the case becomes more tuberculoid.
Reversal reactions often occur in the first months or years after the initiation of therapy but may also develop several years thereafter.
Edema is the most characteristic microscopic feature of type 1 lepra lesions, whose diagnosis is primarily clinical.

Type 2 lepra reaction (Erythema nodosum leprosum )

It is an immune complex mediated hypersensitivity reaction
It is Gell and Coombs type III hypersensitivity reaction
In patients with polar lepromatous or borderline lepromatous leprosy and follows initiation of leprosy treatment
Crops of erythematous, palpable, tender, papular, nodular or plaque lesions distributed bilaterally symmetrically, on face and extensor aspect of extremities.
Skin biopsy - vasculitis or pannieulitis. lymphocytes with polymorphonuclear infiltrates
Elevated levels of circulating TNF-α
Fever and systemic manifestations like polyarthritis, lymphadenopathy, immune complex glomerulonephritis, epididymoorchitis and iridocyclitis.
Risk factors are Multidrug therapy for leprosy, intercurrent infections, pregnancy, trauma, surgery,physical and mental stress
Corticosteroids (prednisolone-0.5 to 1 mg/kg/ day] are the first line drugs
Clofazimine  and thalidomide  are second line drugs
Thalidomide is contraindicated in pregnancy as it is teratogenic.

Lucio's Phenomenon

It is an unusual reaction seen exclusively in patients from the Caribbean and Mexico.
Patients with untreated diffuse lepromatosis form of lepromatous leprosy.
Recurrent crops of large, sharply marginated. ulcerative lesions on the lower extremities.
Secondary infection and septic bacteremia can be fatal.
Histologically, the lesions are characterized by ischemic necrosis of the epidermis and superficial dermis,heavy parasitism of endothelial cells with AFB. and endothelial proliferation and thrombus formation in the larger vessels of the deeper dermis.
Type 1 hypersensitivity reaction
Type 2 hypersensitivity reaction
Type 3 hypersensitivity reaction
Type 4 hypersensitivity reaction