robin082006
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19. Several days after exploring a cave in eastern Kentucky, a 39-year-old
female develops shortness of breath and a low-grade fever. Chest x-rays
reveal several irregular areas in both upper lung fields along with enlarged
hilar and mediastinal lymph nodes. A biopsy of one of these lymph nodes
reveals granulomatous inflammation. Multiple small yeasts surrounded by
clear zones are seen within macrophages. Which one of the following
organisms is most likely responsible for this individual's disease?
a. Aspergillus species
b. Blastomyces dermatitidis
c. C. albicans
d. Histoplasma capsulatum
e. Mucor
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| nadiabarati
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b
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| mazinger
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d
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original mazinger z
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| robin082006
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answer is D
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| nadiabarati
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why not b?
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| robin082006
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19. The answer is d. (Cotran, pp 336, 352–353, 354–357. Rubin, pp
432–440.) H. capsulatum, a dimorphic fungus, causes one of the three major
fungal infections in the United States that may result in systemic infection
(Blastomyces and Coccidioides are the other two). Although H. capsulatum
commonly produces asymptomatic primary disease, it can result in granulomatous
inflammation, especially granulomatous lung disease. Multiple
small yeasts surrounded by clear zones may be found within the cytoplasm
of macrophages. The source for histoplasma is soil contaminated by the
excreta of birds (starlings and chickens) and bats. The typical location for
individuals to develop histoplasmosis is the Ohio and Mississippi Valley
areas. Aspergillus species produce several clinical disease states, including
allergic aspergillosis, systemic aspergillosis, and aspergilloma. Typically
Aspergillus species are seen in tissue as acute angle–branching septate
92 Pathology
hyphae; however, they may form fruiting bodies in cavities, such as within
cystic cavities of the lungs. There they may form a large mass called a fungus
ball or aspergilloma. Blastomycosis is a chronic granulomatosis disease
caused by a dimorphic fungus, B. dermatitidis. In tissues this fungus is seen
as a thick-walled yeast having broad-based budding. Without the budding,
Blastomyces may be mistaken for Cryptococcus. The infection, also known as
Gilchrist’s disease, is seen in individuals living in the Ohio and Mississippi
Valley areas and is usually confined to the lungs. Candida species, which
frequently cause human infections, grow as yeasts, elongated chains of
yeast without hyphae (pseudohyphae), or septate hyphae. Mucocutaneous
candidal infections can produce white plaques called thrush. Mucormycosis
(zygomycosis) is a disease caused by “bread mold fungi” such as Rhizopus,
Mucor, and Absidia species. These infections typically occur in
neutropenic patients or diabetics. One form of the disease, typically found
in diabetics, is called rhinocerebral mucormycosis and is characterized by
facial pain, headache, changing mental status, and a blood-tinged nasal
discharge. Tissue sections reveal characteristic broad, nonseptate, right
angle–branching hyphae.
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The Key to Succeed is Patience.
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| nadiabarati
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hey robin, thanks a looot. microbiology and pharmacology are so volatile and I can't keep them in my mind
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| docarchana
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exploring a cave - histoplasma.
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| klimt
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Right. Goljan says that, for USMLE, any 'idiot' that goes in a cave is at risk to get Histoplasma.
Regions: E Great Lakes, Mississippi, Missouri, Ohio
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