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  #1  
Old 02-07-2011
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Arrow Test your knowledge #3! (Microbiology/Path)

A 35-year-old female with a history of SLE and sporadic serious illness presents with a high fever and dyspnea of acute onset. Chest x-ray reveals bilateral infiltrates, and microscopic examination of sputum smears was inconclusive. Empirical broad-spectrum antibiotic therapy and supportive measures were begun, but the patient died two days after admission. A lung sample obtained on biopsy (below), shows infection with what organism?


  1. Blastomyces dermatitidis
  2. Cytomegalovirus
  3. SNV hantavirus
  4. Pseudomonas aeruginosa
  5. Streptococcus pneumoniae
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  #2  
Old 02-07-2011
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This is the Owl Eye Appearance of CMV infection as outlined by Rasheed here
http://www.usmle-forums.com/usmle-st...ppearance.html
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Old 02-07-2011
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Default confused

my first instinct was CMV too..but then ive done questions with similar presentations n the answer was hanta virus..cuz it causes dyspnea and death..plz confirm the answer...
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Old 02-07-2011
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This may be why I am a bad test taker... But that does not look like Owls eye appearance to me.

My guess is C.
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Old 02-07-2011
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Ya it does look like owls eye to me too..the presentation is confusing though...there has to be something to do with her hablvin sle..maybe she is on immunosupressants and is therefore prone to cmv inf...
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Old 02-07-2011
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I go with A. Blastomyces dermatitidis.
I think i can see a few almost-complete budding yeasts. This is a probably an immunosupressed pt and ARDS is a known complication of Blastomyces.
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Arrow

The most correct answer is A) Blastomyces dermatitidis

I see a doughter cell attaches to the mother cell at a wide bud base. In this qn the pt is experiencing an acute illness like bacterial pneumonia, with symptoms of high fever, dyspnea, and productive cough.

Tx Itraconazole given orally.

Very good qn, plz post more, thank you
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Old 02-07-2011
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Default A. is correct!

Jorgemorales and aktorque are correct - the answer is A. Blastomyces dermatitidis. The rounded budding yeast forms of blastomycosis are shown here (image from NEJM).
  • CMV was the trap foil - the "owl's eyes" of CMV are inclusions with perinuclear halos. As Sandeep pointed out, there are several things which might look like owl-eyes: RS cells, CMV inclusions, giardia, lacunar cells... it's easy to fall into a trap.
  • While you might see abnormal leukocytes and other indications of SNV hantavirus pathophysiology on a normal stain, you would need immunostaining to localize SNV.
  • Pseudomonas would show up as gram-negative rods, much smaller than cells, and pneumococcus would show gram-positive diplococci.
Meka and jorgemorales were right when they pointed out the SLE Hx as indicating possible immunosuppression. Thanks for the Tx, aktorque!


Here are some pictures to help differentiate some owl-eye-looking things:



Above, blastomycosis again
Below, cyotmegalovirus



Above, cytomegalovirus
Below, Reed Sternberg cells



Above, Reed Sternberg cells
Below, Giardia lamblia

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