Two cases of jejunal strictures caused byHistoplasma capsulatum in AIDS patients are presented. Both patients were intravenous drug abusers. One patient, who was being treated for Pneumocystis carnii pneumonia, presented with jejunal perforation and the other presented with lower gastrointestinal bleeding and intestinal obstruction. On exploration, both patients were found to have jejunal strictures; one had intestinal perforation, and the other had intestinal obstruction with ulcers and strictures resulting in gastrointestinal bleeding. In areas where it is endemic, histoplasmosis is rarely disseminated. Dissemination is most commonly seen in immunosuppressed patients. Dissemination and extrapulmonary histoplasmosis is now included in the case definition of AIDS.
- jejunal perforation
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Histoplasmosis is a fungal infection caused byHistoplasma capsulatum that is more commonly seen in endemic areas. Various gastrointestinal manifestations such as perforation, obstruction, and haemorrhage have been reported. With the increasing incidence of AIDS, more cases of histoplasma infection are being reported from non-endemic areas. Thus, it is now important to consider histoplasmosis in the differential diagnosis of immunocompromised patients with acute abdomen. Histoplasmosis is now included in the Centers for Disease Control case definition of AIDS.
A 37 year old Hispanic man, with no recent history of visiting an area where histoplasmosis is endemic, presented with colicky abdominal pain of four months' duration. The pain had worsened during the last two days and was associated with fever. He was a known intravenous drug abuser, had had AIDS diagnosed, and was being treated forPneumocystis carnii pneumonia.
On examination, the patient was febrile with tachycardia. His abdomen was distended, tender, rigid, and had no bowel sounds. Rectal examination revealed tenderness in the anterior wall; his stool was guaiac negative. Radiographs revealed gas under both domes of the diaphragm and distended loops of jejunum. The results of the blood count and biochemical analysis were within normal limits. On exploration, purulent fluid was found in the peritoneal cavity. There was stricture in the mid-jejunum; proximal to the stricture were distended loops of jejunum with perforation (fig 1). Mesenteric lymph nodes were enlarged. The diseased and perforated segment was resected and a primary anastomosis performed. The resected specimen showed focal accumulation of macrophages stuffed with yeast. The yeast form with a thin cell wall, but without a true capsule, was seen with methenamine silver stain. Postoperatively, the patient was treated with intravenous amphotericin B and made an uneventful recovery.
A 24 year old Hispanic man, a known intravenous drug abuser, was admitted with a history of fever of unknown origin. On examination he was found to have generalised lymphadenopathy, oral candidiasis, and pulmonary infiltrates. The patient developed massive lower gastrointestinal bleeding, and then intestinal obstruction. Abdominal radiographs revealed distended loops of jejunum and multiple air fluid levels.
On exploration, distended loops of jejunum were found with a stricture in the distal jejunum obstructing the lumen. There was mesenteric adenopathy. The stricturous segment was resected and a primary anastomosis performed. Histology of the lymph nodes showed the cells were overloaded with characteristic yeast form. The tissue showed localisation of activated mononuclear phagocytes with numerous yeast forms (fig 2). Gross examination of the resected specimen revealed deep linear ulcerations at the site of the stricture, which was responsible for massive bleeding. Postoperatively, the patient was treated with intravenous amphotericin B. Transbronchial biopsy revealedH capsulatum. The patient later developed disseminated histoplasmosis, which proved fatal.
In 1908, Darling first described the diseased caused byH capsulatum, a dimorphic fungus.1 The second case report, by Crumrine and Kessel, was published in 1931.2 Nearly 30 years after the original report, in 1934, De Monbreum described the cultural characteristics of the fungus.3 Since then, many reports have described various facets of the disease.
Histoplasmosis, an endemic disease in the United States, is prevalent in the Ohio-Mississippi Valley.4 Infection of the human host is by the inhalation of spores. After inhalation, 99% of people who are exposed develop a self limiting lesion that is similar to the Ghon complex seen in tuberculosis. Occurrence and resolution of the lesion passes as an asymptomatic incident. Once exposed, people become sensitised to the fungus and the skin test becomes positive. In a few, the disease can become disseminated.5 These individuals usually have some associated risk factors such as old age, lymphoma, immunosuppression, or chronic disease.5 6 There is a 25% association of disseminated histoplasmosis with underlying immunodeficiency disorder.7 However, it is interesting to note that disseminated histoplasmosis is increasing in patients with AIDS in areas where histoplasmosis is not endemic.8-10
Gastrointestinal involvement of histoplasmosis is seen at necropsy in 75% of patients with disseminated disease.11-13 Clinically, 20% of patients with dissemination are symptomatic.14 15 Pulmonary lesions usually precede the gastrointestinal involvement. However, an alternate route of infestation, unlike swallowing spores, has been suggested in patients with isolated gastrointestinal involvement.16-20Often in disseminated histoplasmosis the entire gastrointestinal tract is involved, although segmented involvement also is reported.21-23 Intestinal lesions include pseudopolyps and ulceration either constricting or perforating diffuse granulomatous lesions.24-29
Ulceration of the gastrointestinal tract occurs anywhere from the nasopharynx to the rectum.
In a review of the literature beginning in 1906 we found 10 reported cases of histoplasma infection presenting as stricture of a segment of the stomach, ileum, or colon. The distal ileum is the most common site involved, followed by colon and stomach.7 21 22 24 29 30 Ours are the first reported cases of jejunal stricture in patients with AIDS. There is one case report from Africa of a case caused by H duboisia (African histoplasmosis) in a 36 year old Nigerian women.31 However, this patient did not have any immunosuppressive factors. Heneghan et alreported a case of ileal stricture with perforation in a patient with AIDS.7 Colonic granuloma presenting as an abdominal mass mimicking carcinoma of the colon is reported by Haggertyet al.32
Gastrointestinal presentation of histoplasmosis has no specific symptomatology. It can present with bloody diarrhoea, which can cause confusion with ulcerative colitis, or Crohn's disease, as in our case, and can cause intestinal obstruction, perforation, or gastrointestinal bleeding. In fact, we considered tuberculosis of the intestine as the differential diagnosis of our patient with stricture and lymphadenopathy.
The diagnosis of the gastrointestinal histoplasmosis usually requires tissue for culture or histological identification of the infecting organism. Detection of the antibodies to H capsulatum has shown not to be accurate in patients with AIDS.13 33 Wheat et al have described the use of radioimmunoassay histoplasma polysaccharide antigen for the diagnosis of disseminated histoplasmosis.34 A positive histoplasma skin test in areas where histoplasmosis is endemic, however, is not of much use because the population generally has been sensitised, but it may be of importance in other areas. In patients with AIDS, however, the test has not been reliable. Untreated histoplasmosis has a mortality rate of 83%.35-37
The optimal treatment of disseminated histoplasmosis in the AIDS population has not been firmly established. Intravenous amphotericin has been effective over a prolonged period of time. Some investigators have found oral antifungal agents to be effective in immunocompromised patients with disseminated histoplasmosis,36 37 and others have found less success and relapse rates as high as 25% in patients with AIDS. The current recommended treatment includes intravenous amphotericin during the rapidly progressive phase of the disease followed by maintenance therapy with amphotericin B given weekly or itraconazole twice a day.38 39
In summary, gastrointestinal histoplasmosis is not a commonly considered diagnosis in AIDS patients presenting with gastrointestinal symptoms. The fact that the infection has increasingly been reported in AIDS patients in areas where histoplasmosis is not endemic makes it important that this diagnosis be considered when dealing with an acute abdomen in AIDS patients.