The Journal of the Arkansas Medical Society Med Journal June 2019 Final | Page 11

causes of bloody diarrhea in these patients. 1
Sometimes, coinfection with two different or-
ganisms can cause severe diarrhea, as in our
patient. Hence, we need to be very cautious.
Histoplasma is a common, opportunistic
infection in HIV/AIDS patients living in endemic
areas. Histoplasmosis is caused by an invasive
fungus called Histoplasma capsulatum, which is
endemic to certain parts of U.S. including Mis-
sissippi, Ohio, and the St. Lawrence River Val-
ley. The fungus is found abundant as spores in
the soil that is contaminated by bird feces. The
disease is transmitted upon inhalation of the
spores, which convert into yeast form. They are
engulfed by macrophages, where they multiply
and spread throughout the body via reticulo-
nodular system. In immunocompetent patients,
infection is usually self-limited and most often
time goes unnoticed. However, patients who are
immunocompromised can have serious illness.
It can present either with isolated pulmonary
infection or disseminated disease with multi-
organ involvement (skin, GI tract, liver, spleen,
meninges, kidneys, adrenal glands, etc.).
Histoplasma can be identified in the GI tract
of 70-90% patients with disseminated disease,
but only 3-12% of those are symptomatic. 2,3 It
usually presents with non-specific symptoms
like fever, night sweats, nausea, vomiting, diar-
rhea, abdominal pain, hematochezia, melena, 4
and oropharyngeal ulcerations. Sometimes it
can present as a mass leading to intestinal ob-
struction. Lesions occur anywhere in the GI tract
from mouth to anus but are more common in the
terminal ileum due to abundance of lymphoid
tissue. 5,6 Typical endoscopic lesions are patchy
or continuous superficial-deep ulcerations, ac-
companied by diffuse mucosal erythema, and
rarely as polypoid masses causing obstruction or
annular constricting ulcers leading to strictures. 6
These findings can often be misdiagnosed for
malignancy or IBD; hence, a careful evaluation
and high index of suspicion is warranted. Mouth
ulcers are usually very painful and can mimic
malignancy by their appearance.
Antigen detection in tissues samples (blood,
urine, BAL) is useful for diagnosis of dissemi-
nated histoplasmosis. It is positive in >90%
patients with disseminated disease. However, it
may be falsely negative in patients with local-
ized GI involvement. Hence, biopsy is warranted
Image 2a: Photomicrograph showing active colitis with ulcerated colonic mucosa;
2b: Extensive accumulation of macrophages within lamina propria; 2c: Image
showing positive PAS stain; 2d: GMS stain highlights accumulation of numerous
intracellular 2-4 um fungal spores consistent with Histoplasma capsulatum.
for appropriate and accurate diagnosis. Pathol-
ogy suggests abundant inflammatory infiltrate
and multiple intracellular, ovoid-spherical, nar-
row-based budding yeast cells, visualized bet-
ter with methenamine silver stain. Treatment is
not indicated for mild pulmonary illness or self-
limiting illness (symptoms lasting for <1 month).
However, all disseminated histoplasmosis, acute
pulmonary histoplasmosis with symptoms last-
ing for > one month, or those who have hypoxia,
need to be treated. Treatment is divided into
two different phases: induction treatment and
lifelong suppressive therapy. Patients with less
severe disease may be treated with itraconazole,
but amphotericin-B is merited in moderate-se-
vere disease. 4 Length of induction therapy varies
depending on the severity of illness and is usu-
ally in weeks. As patients have a high chance of
relapse, lifelong suppressive therapy with either
itraconazole or fluconazole is warranted. Trials
have shown better remission with itraconazole
compared to fluconazole. Some people use se-
rum antigen levels to monitor response to ther-
apy. Disseminated histoplasmosis carries high
mortality (~80%), hence early identification and
treatment is necessary.
CONCLUSION
Coinfection with common nosocomial bugs
like Clostridium difficile may masquerade the
underlying histoplasmosis, hence a high index
of suspicion is essential, especially in immuno-
compromised patients. Due to a lack of specific
signs and symptoms for GI histoplasmosis, this
entity may be missed many times. Any patient
with unexplained GI symptoms in HIV/AIDS pa-
tients should be evaluated for histoplasmosis. 7
Disseminated histoplasmosis carries high mor-
tality up to 80%, hence early identification and
treatment is necessary. Treatment decreases
mortality to less than 25%.
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3. Kahi CJ, Wheat LJ, Allen SD et al. Gastroin-
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