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Thursday 12 March 2009

Definition : Histoplasmosis is a granulomatous disease caused by the intracellular dimorphic fungus Histoplasma capsulatum .


- digestive histoplasmosis

- bone marrow aspirate with disseminated histoplasmosis

- Hyphae of Histoplasma. Rarely seen unless intravascular, as in endocarditis

- Histoplasma in a nerve / intraneural histoplasmosis

- pulmonary histoplasmosis / Histoplasma granuloma

- Histoplasma caspulatum : Grocott stain or GMS stain

- disseminated histoplasmosis in an immunosuppressed patient

- Histoplasma capsulatum in macrophages

- Histoplasma capsulatum

Histoplasma capsulatum is found most commonly in North America and Central America, but the fungus has been reported from diverse areas around the world.

In endemic areas infection occurs during day-to-day activities that lead to disruption and subsequent inhalation of soil contaminated with bird or bat guano.

In areas endemic to histoplasmosis the vast majority of infections are either asymptomatic or present as a mild illness that is never recognized as being histoplasmosis.

Clinically, histoplasmosis may present as a pulmonary (acute pulmonary histoplasmosis, chronic cavitary pulmonary histoplasmosis, granulomatous mediastinitis and mediastinal fibrosis) or a disseminated infection.

Disseminated histoplasmosis has become increasingly important with the advent of new and expanding population of immunocompromised patients.

Although respiratory tract is the primary site of the disease, virtually all organs rich in mononuclear cells can be infected.

Primary gastrointestinal infections are an uncommon presentation of the infection, almost always associated with disseminated form of the disease and/or immunodeficiency.

Symptomatic gastrointestinal tract infection is more common in AIDS patients and can mimic other AIDS associated opportunistic infections that cause diarrhoea. The colon is the most commonly involved site followed by small bowel with lesions presenting as ulcerations, polyps, strictures or perforations.

Histoplasmosis has been reported both in immunocompetent as well as immunocompromised patients with disseminated forms being more common in the latter group.

In HIV positive patients the prevalence of histoplasmosis varies from 5% to 32% depending on the endemicity of the disease. In HIV infected patients, working in chicken coops, CD4 count @<@150 cells/μL and positive baseline complement fixing antibodies to histoplasma antigen have been identified as possible risk factors for histoplasmosis.

Diabetes mellitus and HIV infection are the most common co-morbid conditions.

Weight loss and fever were found to be the most common symptoms while on physical examination; oropharyngeal ulcers, hepatosplenomegaly and lymphadenopathy were the most common signs.


- gastrointestinal tract infection

  • ulcerative lesions in the rectum, ileum and oesophagus
  • multiple intestinal hemorrhages

- lymphadenopathy
- hepatomegaly
- hepatosplenomegaly
- oropharyngeal ulcer

- In disseminated histoplasmosis, the yield of blood and sputum culture has been reported to be 75% and 50%, respectively.


- pulmonary histoplasmosis
- digestive histoplasmosis
- disseminated histoplasmosis

Case studies

- Case #601

See also

- Histoplasma capsulatum


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- Cimponeriu D, LoPresti P, Lavelanet M, Roistacher K, Remigio P, Marfatia S, et al . Gastrointestinal histoplasmosis in HIV infection: Two cases of colonic pseudocancer and review of literature. Am J Gastroenterol 1994;89:129-31.

- Subramanian S, Abraham OC, Rupali P, Zachariah A, Mathews MS, Mathai D. Disseminated histoplasmosis. J Assoc Physicians India 2005;53:185-9.

- Goswami RP, Pramanik N, Banerjee D, Raza MM, Guha SK, Maiti PK. Histoplasmosis in eastern India: The tip of the iceberg? Trans R Soc Trop Med Hyg 1999;93:540-2.

- McKinsey DS, Gupta MR, Riddler SA, Driks MR, Smith DL, Kurtin PJ. Long-term amphotericin B therapy for disseminated histoplasmosis in patients with the acquired immunodeficiency syndrome (AIDS). Ann Intern Med 1989;111:655-9.

- McKinsey DS, Spiegel RA, Hutwagner L, Stanford J, Driks MR, Brewer J, et al . Prospective Study of histoplasmosis in patients infected with human immunodeficiency virus: Incidence, risk factors and pathophysiology. Clin Infect Dis 1997;24:1195-203.

- Lee JT, Dixon MR, Murrell Z, Konyalian V, Agbunag R, Rostami S, et al . Colonic histoplasmosis presenting as colon cancer in the nonimmunocompromised patient: Report of a case and review of literature. Am Surg 2004;70:959-63.

- Wheat J. Histoplasma, Chapter 278. In : Infectious Diseases, 2 nd ed. Gorbach SL, Bartlett JG, Blacklow NR, editors. W.B. Saunders Company: Philadelphia; 1998. p. 2339.