Histoplasmosis is an endemic mycosis caused by the Histoplasma capsulatum fungus. This fungus is acquired through the inhalation of microconidia and more than 90% of cases are asymptomatic.1 Symptomatic intestinal involvement is extremely rare and clinical presentation depends on patient age and immunosuppression status, as well as on the size of the inoculum.2

A 45-year-old man from Tarapoto, Peru, came to the hospital presenting with diffuse, colicky abdominal pain, bloody diarrhea, diaphoresis, and fever of 38 °C for a period of three weeks. He went to the emergency service for having presented with hematochezia. Laboratory analyses reported the following: leukocytes: 10,000/mm3, bands: 0%, segmented cells: 88.9%, hemoglobin: 7.8 g/dl, platelets: 346,000/mm3, ELISA HIV: nonreactive, HTLV I and II: negative. Colonoscopy: multiple ulcers in the ascending colon, transverse colon, descending colon, sigmoid colon, and rectum, with congestive edges and whitish fibrin in the wound bed (Fig. 1a). The pathologic anatomy study of the colonic biopsies showed chronic inflammation and multiple macrophages, with microorganisms in their interior, consistent with histoplasma (Fig. 1b). Gomori staining was positive for mycosis (Fig. 1c). Intravenous liposomal amphotericin B, 3 mg/kg/day, was administered for 2 weeks. The patient had clinical improvement and was discharged. As an outpatient, he continued treatment with itraconazole, 200 mg every 12 hours, for one year. At the one-year follow-up, the patient is asymptomatic.

Figure 1.

a) the presence of ulcers in the sigmoid colon, b) the pathologic anatomy study with hematoxylin-eosin staining revealed multiple purple, sphere-shaped microorganisms, surrounded by a whitish halo, consistent with histoplasmosis, and c) Gomori staining showed the presence of multiple microorganisms consistent with mycosis.

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In Latin America, histoplasmosis is highly endemic, with a prevalence of 32%. This mycosis can manifest from the mouth to the anus; the most frequently affected sites are the ileum and colon.3 Intestinal manifestations occur in 2-3% of cases and the most frequently reported clinical symptoms are abdominal pain, diarrhea, and fever.4 Endoscopically, histoplasmosis involving the colon can present as an ulcer or pseudotumor, and there can be complications, such as gastrointestinal bleeding, intestinal obstruction, or intestinal perforation.5 Diagnosis consists of the presence of microorganisms in the histology study, which in hematoxylin-eosin staining are characteristically round, purple, and surrounded by a whitish halo. Other infections, such as tuberculosis, inflammatory bowel disease, or neoplastic processes, such as lymphoma, should be considered in the differential diagnosis.6 In disseminated forms, the treatment of choice is 3 mg/kg/day of liposomal amphotericin B for 1-2 weeks, followed by itraconazole 200 mg every 8 hours for 3 days, and then itraconazole 200 mg every 12 hours for 12 months.7,8

In conclusion, intestinal histoplasmosis can appear in immunocompetent patients from endemic zones, with the clinical symptoms of abdominal pain, diarrhea, and fever.