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Amoeba infection has become increasingly common with the appearance of AIDS and immunosuppressant agents. The most important amoebas include Acanthamoeba, Naegleria, and Balamuthia, and Entamoeba histolytica. The free-living amoebas, belonging to three groups: amoeboflagellates (Naegleria), Acanthamoebidae, and Leptomyxida (Balamuthia), are ubiquitous and have been isolated from air, soil, and water samples throughout the world.


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Naegleria fowleri Primary amebic meningoencephalitis

Chronic Acanthamoeba keratitis (AK) in contact lens wearers or those with minor corneal abrasions

The pathogenic species of Acanthamoeba include:

A. castellanii, A. polyphaga, A. culbertsoni, A. palestinensis, A. astronyxis, A. hatchetti, and A. rhysodes.

The primary site of entry commonly respiratory tract with hematogenous dissemination, and skin

Disseminated acanthamoebiasis in AIDS patients may initially present as cutaneous lesions

Patient’s age ranges from 5–60 years, with a mean age of 32 years. The male to female ratio is 6:1. An immunocompromised condition is almost uniformly reported

Clinically, the skin lesions may present as pustules, subcutaneous and deep dermal nodules, or chronic ulcers, most commonly involving the extremities or face

Acanthamoeba species (spp.) and Balamuthia mandrillaris Can cause granulomatous amoebic encephalitis (GAE) with dissemination to other tissues



Acanthomoeba infections show acute and chronic inflammatory dermal infiltrates with foci of necrosis, and granulomata

Other features include vasculitis, subcutaneous fat necrosis, and panniculitis

Amebiasis cutis revisited.

Department of Pathology, Nelson R Mandela School of Medicine, University of KwaZulu Natal and Inkosi Albert Luthuli Central Hospital, Durban, KwaZulu Natal, South Africa.


J Cutan Pathol. 2007 Aug;34(8):620-8. Abstract quote

Background: Amebiasis cutis (AC) is reported infrequently. This study assesses the clinicopathological spectrum, co-existent visceral involvement and impact of human immunodeficiency virus (HIV) co-infection on AC.

Methods: An 8-year prospective clinicopathological evaluation of patients with AC.

Results: Thirty-one biopsies of ulcers, fistulae, fissures, abscesses, polypoid and warty lesions in perianal, penile, scrotal, vulval, buttock, chest and abdominal wall sites were evaluated. Of these, 11 had a 'superficial' (superficial AC) and 20 a 'deep' (deep AC), histopathological pattern. Superficial AC showed predominant epidermal spongiosis, liquefactive necrosis, ulceration and fissures with hematophagous amebic trophozoites (HATs). Deep AC had confluent deep dermal and subcutaneous liquefactive, coagulative or suppurative necrosis and HATs. Seven biopsies showed vasculitis or thrombosis with luminal HATs.

Outcome: Fourteen patients died; 9 had concomitant visceral amebiasis, 5 had other co-infections. Six who died were HIV seropositive, three were seronegative; all had deep AC. Of the 17 survivors, 11 (8 HIV positive) had superficial AC that healed with metronidazole treatment; the remaining 6 (one HIV seropositive) required additional surgical intervention.

Conclusion: Deep AC is predictive of co-existent, contiguous visceral disease. The effective management, histopathological mimickers and diagnostic pitfalls of superficial and deep AC differ. The outcome in HIV-infected patients is dependent on co-existent systemic diseases.
Histopathology of cutaneous amebiasis.

Magana M, Magana ML, Alcantara A, Perez-Martin MA.

Hospital General de Mexico/Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
Am J Dermatopathol. 2004 Aug;26(4):280-4. Abstract quote

Cutaneous amebiasis (CA) is the manifestation in the skin and underlying soft tissues of the pathogenic properties of Entamoeba histolytica, which may be the only expression of the infection or may be associated with disease in other organs. So far, there have been only isolated case reports on this disease.

We herein report the histopathologic findings on a series of seven cases, six adults and one child, of CA. The most common findings include ulcers, areas of necrosis, mixed inflammatory infiltrates, and the presence of trophozoites, the invasive form of the parasite. CA is a very rare and severe disease, it is progressive and destructive; erythrophagocytosis, a microscopic sign of pathogenicity, is always seen in CA.

Disseminated acanthamoebiasis presenting as lobular panniculitis with necrotizing vasculitis in a patient with AIDS

Arlene Sylvia Rosenberg1 and Michael B. Morgan

Journal of Cutaneous Pathology 2001;28 (6): 307-313 Abstract quote

Background: Disseminated acanthamoebiasis is a rare entity, almost exclusively occurring in the immunocompromised host.

Methods: We report an unusual case of a 35-year-old female with recurrent sinusitis and multiple skin nodules demonstrating a necrotizing panniculitis, shown to be due to disseminated acanthamoebiasis.

Results: Histologic sections showed a neutrophilic lobular panniculitis with 20- to 30-mm trophozoites consistent with Acanthamoeba species.

Conclusions: A review the literature shows that the histopathological presentation of acanthamoebiasis often eludes initial diagnostic attempts and that central nervous system (CNS) involvement is frequent and ultimately fatal. When amoebiasis is suspected, knowledge of the trophozoite and cyst forms may be helpful in distinguishing Acanthamoeba species from Entamoeba histolytica.

Macpherson and Pincus. Clinical Diagnosis and Management by Laboratory Methods. Twentyfirst Edition. WB Saunders. 2006.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

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Last Updated August 21, 2007

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