Leprosy (Hansen’s Disease) | Figure 4.18
A: Scrofuloderma
(Courtesy of Dr. Paul Getz)
B: Lepromatous leprosy
(Courtesy of Dr. Paul Getz)
C: Erythema nodosum leprosum
(Courtesy of Dr. Paul Getz) |
(Figure 4.18B) - Deforming and stigmatizing chronic granulomatous disease caused by M.leprae, which affects primarily skin and peripheral nerves
- Incubation typically 3–5 years, but can be 20+ years
- Transmission primarily via respiratory droplets
- Cellular immunity crucial for elimination of M.leprae
- Classification of disease based on host’s level of cell-mediated immunity (see Table 4-12)
- LL (lepromatous leprosy) ↔ BL (borderline lepromatous) ↔ BB (midborderline) ↔ BT (borderline tuberculoid) ↔ TT (tuberculoid leprosy)
- Of note, patients can move through spectrum of disease via upgrading and downgrading reactions
- Reactional states: immunologically mediated inflammatory states occurring spontaneously or after initiation of treatment (see Table 4-13)
- Diagnosis
- Acid-fast bacilli in tissue sections or smears using Fite-Faraco stain; in LL, macrophages loaded with bacteria and have foamy appearance (Virchow cell), in TT epithelioid tubercles surrounded by lymphocytes
- No culture medium for M.leprae (can only be grown in mouse foot pad or nine-banded armadillo)
- Treatment (WHO recommendation)
- Multibacillary → 12-month duration: dapsone 100 mg daily, clofazamine 50 mg daily and 300 mg monthly, rifampin 600 mg monthly
- Paucibacillary → 6-month duration: dapsone 100 mg daily, rifampin 600 mg monthly
- Of note, patients are no longer infectious after first or second dose of rifampin
| | | | | | | Table 4-12 Spectrum of Leprosy | | | Tuberculoid Leprosy (TT) | | Borderline Leprosy | | Lepromatous Leprosy (LL) | | | TH1 response (IL-2, IFNγ, IL-12)
↑ Cell-mediated immunity (intact CMI allows localization of infection) | | BL, BB, BT | | TH2 response (IL-4, IL-10)
↓ Cell-mediated immunity (lack of CMI allows progression of infection) | | | CD4+ cell predominance | |  | | CD8+ cell predominance | | | ↓↓ Viable organisms (paucibacillary) | | | | ↑↑ Viable organisms (multibacillary) | | | Clinical presentation:
One to few well-demarcated erythematous slow-growing plaques with central clearing; lesions typically become anesthetic, anhidrotic, and hypopigmented
Tender, thickened nerves (predilection for superficial nerves with cooler temperature)
May present with neural involvement alone | | Features of both | | Clinical presentation:
Poorly defined symmetric skin-colored to erythematous macules, papules, nodules, and/or plaques; dermal infiltration leads to: face → “leonine facies” eyebrows → lateral alopecia (madarosis)
Enlarged peripheral nerves, “stocking/ glove” anesthesia
Testicular infection → sterility
Lagophthalmos and corneal anesthesia | | | | | | | |
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| | | | | | | Table 4-13 Leprosy Reactional States (Figures 4.18C and 4.19A) | | Reaction | | Pathogenesisis | | Clinical Findings | | Treatment | | | Type 1 Reaction
Reversal reaction | | Change in cell-mediated immunity in BL patients: upgrading to more resistant state (↑ destruction of bacilli) or downgrading to less resistant state | | –Upgrading: skin lesions become acutely inflamed, rare new lesions; neuritis with rapid-onset pain, swelling, tenderness, and loss of function of affected nerves
–Downgrading: lesions acutely inflamed, new lesions; neuritis | | Systemic corticosteroid (40 mg to 80 mg) and taper over several weeks | | | Type 2 Reaction
Erythema nodosum leprosum (ENL) | | Upgrading reaction in BL and LL patients during treatment: ↑ antibody levels leads to immune complex deposition in vessels → small vessel vasculitis | | Presents with deep, painful erythematous nodules on face or trunk
Fever, malaise, neuritis, iridocyclitis, arthralgias | | Thalidomide
Clofazamine and
systemic corticosteroid
may also be added | | | Type 3 Reaction
Lucio reaction | | Extensive, severe vasculitis in untreated LL patients | | Presents with pink, painful hemorrhagic or necrotic nodules, ± ulceration, bulla formation, eschars | | Systemic corticosteroid | | | | | | | | | | | |
| | | | | | | | | Of note, always continue antimycobacterial treatment when treating leprosy reactions | | | | | | | | |
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