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leprosy (Hansen's disease)

Etiology: caused by Mycobacterium leprae Classification: 1) indeterminate a) frequently initial form b) resolves spontaneously or evolves into other forms 2) lepromatous a) most contagious form b) mainly affects skin c) peripheral nerves may be affected d) other symptoms may be present 3) tuberculoid a) affects skin & peripheral nerves b) generally few lesions 4) borderline - intermediate between lepromatous & tuberculoid forms Epidemiology: - endemic in tropical & subtropical regions (India, Brazil, Indonesia) - rare in the U.S. (150-250 cases/year) - only 18% of people born outside the U.S. but later diagnosed with leprosy had symptoms before entering the U.S. [5] - incubation period often lasts 3-7 years [5] - armidillos may be carriers in southwest US [4] - ~100 cases/years reported in U.S. (CDC) Pathology: - chronic granulomatous disease - associated with depressed cellular immunity - humoral immunity appears to be intact - etiologic agent M leprae thrives particularly in peripheral Schwann cells & macrophages - dystroglycan is a receptor for the entry of Mycobacterium leprae into peripheral nerve Schwann cells Microscopic pathology: - perivascular & perineural pattern - thrombosis of medium-sized arteries, with surrounding lymphohistiocytic infiltrate containing plasma cells & foamy macrophages - acid-fast bacilli with invading vascular endothelial wall may be seen on tissue staining (Fite-Faraco) * images (histopathology) [6] Genetics: 1) susceptibility associated with locus on chromosome 10p13 2) polymorphisms in 5' regulatory regions shared by PARK2 & PACRG genes also confer susceptibility (chromosome 6q25-27) 3) genetic variations in TLR2 are associated with suceptibility to leprosy 4) polymorphisms in lymphotoxin-alpha (LTA) accounts, in part, for susceptibility to leprosy linked to chromosome 6p21.3 Clinical manifestations: 1) incubation period often lasts 3-7 years [5] 2) nasal discharge 3) dysphagia 4) hoarseness 5) skin manifestations a) skin lesions are indurated & may be hypoesthetic or anesthetic b) skin nodules, macules & papules symmetrically distributed on forehead, cheeks, ears c) persistent ulcerations d) coalescent ulceronecrotic areas over the trunk, arms, & legs [6] e) painful, blistering skin lesions (case report) [6] f) case of scattered painless skin nodules on distal extremities - hypoesthesia noted within lesions g) retiform purpura [6] h) loss of eyebrows, swelling of earlobes, absence of facial wrinkles, diffuse alopecia (case report) [6] 6) generalized lymphadenopathy 7) persistent neuropathy 8) saddle nose deformity * images (Lucio's phenomenon, diffuse lepromatous leprosy) [6] Laboratory: 1) culture of organisms from blood & nasal secretions 2) false positive VDRL 3) anemia 4) skin biopsy Management: 1) rifampin, clofazimine & dapsone for 12 months 2) rifampin, ofloxacin & minocycline as a single dose for paucibacillar leprosy 3) systemic glucocorticoids & anticoagulation for diffuse lepromatous leprosy [6]

Related

Mycobacterium leprae parkin coregulated gene protein; molecular chaperone/chaperonin-binding protein; PARK2 coregulated gene protein (PACRG, GLUP)

General

mycobacterial infection granulomatous disease

Database Correlations

OMIM correlations

References

  1. Stedman's Medical Dictionary 26th ed, Williams & Wilkins, Baltimore, 1995
  2. DeGowin & DeGowin's Diagnostic Examination, 6th edition, RL DeGowin (ed), McGraw Hill, NY 1994, pg 905
  3. Ramose-e-Silva M & Rebello PF, Am J Dermatol 2:203, 2001
  4. Truman RW et al. Probable zoonotic leprosy in the southern United States. N Engl J Med 2011 Apr 28; 364:1626. PMID: 21524213
  5. Nolen L et al Incidence of Hansen's Disease - United States, 1994-2011 MMWR. Weekly October 31, 2014 / 63(43);969-972 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6343a1.htm
  6. Tajalli M, Wambier CG Images in Clinical Medicine: Lucio's Phenomenon. N Engl J Med 2021; 384:1646. April 29 PMID: 33913641 https://www.nejm.org/doi/full/10.1056/NEJMicm2025081
  7. Elkston CA, Elkston DM Bacterial Skin Infections: More Than Skin Deep. Medscape. July 19, 2021 https://reference.medscape.com/slideshow/infect-skin-6003449
  8. White C, Franco-Paredes C. Leprosy in the 21st century. Clin Microbiol Rev. 2015 Jan;28(1):80-94. PMID: 25567223 PMCID: PMC4284303 Free PMC article. Review.
  9. Rodrigues LC, Lockwood DNj. Leprosy now: epidemiology, progress, challenges, and research gaps. Lancet Infect Dis. 2011 Jun;11(6):464-70. PMID: 21616456 Review.
  10. Maymone MBC, Laughter M, Venkatesh S et al Leprosy: Clinical aspects and diagnostic techniques. J Am Acad Dermatol. 2020 Jul;83(1):1-14. PMID: 32229279 Review.
  11. Alemu Belachew W, Naafs B. Position statement: LEPROSY: Diagnosis, treatment and follow-up. J Eur Acad Dermatol Venereol. 2019 Jul;33(7):1205-1213. PMID: 30945360 Review.