NBME Answers : shervinbd's page

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submitted by lsp1992(24), visit this page

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Can someone please explain what we're seeing on the histo slide? I chose the correct answer because I was thinking fungus because of the immunocompromise and neutropenia (and I thought PAS was used for aspergillus), but I don't see anything fungus-related on that slide.

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cassdawg I think this is Blastomyces (broad based buds) where the darker pink are the blastomyces budding. Here are some similar slides: https://images.slideplayer.com/25/7691707/slides/slide_39.jpg https://www.gettyimages.co.uk/detail/photo/blastomycosis-in-the-brain-caused-by-the-high-res-stock-photography/vis303384 It could also be cryptococcus potentially (https://www.omicsonline.org/publication-images/diagnostic-pathology-budding-cryptococci-3-139-g005.png) but I think the bud bases are too broad and there is no clearing/visible capsule that cryptococcus is notable for. Either way you treat both systemic mycoses with amphotericin. +10

passplease How did you eliminate CMV? +2

cassdawg For me, CMV would have the characteristic "owl eye intranuclear inclusion" cells on biopsy but would be less likely to show anything in pleural fluid (i.e. thoracocentesis would not be used to diagnose CMV). Further CMV pneumonitis is an atypical/interstitial pneumonitis (diffuse patchy infiltrates on CXR, FA2020 p683) and he has a lower lobe consolidation with pleural effusion (more characteristic of fungal pneumonia). +6

shervinbd Looks like Cryptococcus neoformans to me. +4

chaosawaits I was pretty confident that this is Cryptococcus but the more I look at it, the more I don't know +1

submitted by cassdawg(1781), visit this page

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I think this is Strongyloides stercoralis (threadworm) is a roundworm whose larvae live in soil and who can cause pulmonary disease. It has the ability to penetrate skin from the soil but can also be obtained by ingesting feces contaminates soil (FA2020 p159) https://www.cdc.gov/parasites/strongyloides/gen_info/faqs.html

Most intestinal roundworms are fecal-oral route except strongyloides which can also penetrate skin, hookworm (necator americanus) which only penetrates skin, and trichinella which can come from undercooked meats (especially pork) but whose symptoms do not match that of the patient. Trichinella larvae enter the blood stream and infect muscle and can also cause trichinosis with fever, nausea, vomiting, periorbital edema, and myalgia.

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shervinbd I think it is Ascaris, not Stringlyloides. The symptoms could be explained by Loeffler syndrome, caused by Ascaris larva migration. Ascaris is transmitted through fecal oral route, so ingestion of feces contaminated soil could cause the problem. Per FA, Strongylides is transmitted by larva penetrating skin. +23

drmifta Its Ascaris. Fecal oral transmission -> Larvae penitrate GIT -> Blood Stream -> Lung {Maturation, Respiratory Symptom} -> Coughed up and swallowing -> Adult Warm in GIT -> Egg release -> Egg in stool. +1

i_hate_it_here Didn't the stem mention that roundwarm larvae were found? I thought Ascaris is diagnosed by bile coated eggs in feces? +1

sexymexican888 I actually think @cassdawg is right. Its strongyloides. They found larvae in the feces (you find eggs in feces with ascaris) you can get pulmonary sx in both. Ascaris is also usually fecal oral transmission so its more likely to come from someone making food with contaminated hands. Strongyloides is transmitted through soil or sand and the larvae penetrate your feet so this makes more sense. +2

sexymexican888 You can find this is FA 2020 Pg 159. Also if you look at the table strongyloides is assoc. with pulmonary sx. However I think its both cause according to sketchy micro ascaris presents with respiratory sx +

coco Although Strongyloides nematode worm infections are not overly common in the United States, the Appalachian area of the Southeast have reported cases. Ascaris lumbricoides is a common parasitic infection in Asia, Africa, and South America. Most cases in the United States arise in travelers to these regions. Loeffler syndrome can be caused by Strongyloides and Ascaris. Ascar:Stool microscopy reveals an oval egg with a thick outer shell and a single interior ovum Strongyloides:rhabditiform larvae seen in feces under microscope so.I think this is Strongyloides.If I make a mistake,please correct me. +2

melanoma I think is ascaris lumbricoides also due to the size of the larva. UW Q 15549 +