Skin nontumor

Infectious disorders


Topic Completed: 1 July 2011

Minor changes: 16 November 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Leishmaniasis infection [title]

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Leishmaniasis. website. Accessed December 4th, 2021.
Clinical features
  • Protozoal disease in all continents except Australia and Antarctica
  • 1 - 2 million new cases per year worldwide
  • Epidemics occur periodically in tropical regions of world; also infections in HIV+ patients
  • Produces crusted, indurated papule that slowly enlarges and is self limited, as well as fatal systemic illness
  • Disease is either cutaneous, mucocutaneous or visceral
  • May may be misinterpreted as sarcoidosis, foreign body reaction, granulomatous rosacea and even granuloma annulare

  • Cutaneous: usually restricted to face, scalp, arms or other exposed areas
  • Localized, disseminated (if immune system doesnt respond to invading parasites), recurrent (recidivans cutaneous) or post-kala azar (rare, years after visceral disease)

  • Mucocutaneous: usually New World disease of rural and jungle regions
  • Occurs when primary infection with L. braziliensis becomes disseminated to upper respiratory tract, produces lesions of oral, pharyngeal or nasal mucosa with ulceration, mutilation or sometimes death

  • Visceral: also called kala azar; parasites throughout reticuloendothelial system, causing fever, malaise, hepatosplenomegaly, anorexia, pancytopenia, hypergammaglobulinemia
  • Usually spares skin except for irregular areas of dark pigmentation (kala azar means black sickness)
  • May cause death if untreated
  • Broadly divided into old world (tropical and subtropical Asia, India, Africa and Mediterranean) and new world (Americas)
  • Old world: usually Leishmania tropica complex
  • New world: L. braziliensis complex and L. mexicana complex
  • L. braziliensis may also produce espundia, a destructive mucocutaneous form
  • Human infection through bite of Phlebotomus sand fly (smaller than mosquitoes); rarely through blood contamination
  • Clinical presentation and prognosis vary based on species, duration of infection and immune status of patient
  • US infections primarily through travel and HIV infection

    Images hosted on other servers:

    Life cycle

  • Intradermal delayed hypersensitivity test (Montenegro); culture on NNN agar using smears from ulcer; also ELISA, DNA probes, PCR
  • Also by identifying parasites on H&E or in smears, by culture on specialized media, by leishmanin intradermal skin test (Montenegro test), by fluorescent antibody tests using the patient's serum, or by PCR using species-specific primers (but PCR results can be false positive)

  • Note: leishmanin test is usually negative in the forms with cell-mediated hyporeactivity, such as the diffuse cutaneous forms and the visceral form (kala-azar)
Clinical images

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Cutaneous and mucosal forms

Microscopic (histologic) description
  • Dermal granulomatous inflammation with prominent lymphocytes
  • Histiocytes contain small oval organisms with bar shaped paranuclear kinetoplast
Microscopic (histologic) images

Contributed by Dr. Josehp Christopher Castillo

Skin nontumor

Contributed by Venna Maheshwar, M.D., Kiran Alam, M.D. and Anshu Jain, M.D.

Various images

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Bone marrow aspirate smear of visceral leishmaniasis

Positive stains
  • Weigert iron hematoxylin may stain parasites better than H&E or Giemsa
  • Immunohistostain using G2D10 antibody is more sensitive than H&E
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