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 +0  (nbme24#3)

BUT why is the serum potassium normal?

I was able to narrow it down to RTA, because none of the other answer choices made much sense, but the potassium had me second guessing myself. Can someone explain that lab finding? Thanks!

subclaviansteele  My take is that hes not super acidotic and the K is at the low end.
nwinkelmann  see the comment by @zbird, which explains that the urine anion gap is important (which I took to interpret as more important than the serum K+ level, lol, because the normal K threw me off too).

 +5  (nbme24#6)

The presentation here seems to fit that of mesenteric vascular occlusion- postprandial pain that lasts 1 hour, food aversion, weight loss. The patient also has risk factors associated with mesenteric vascular occlusion- older than 60 years old, Hyperlipidemia, Hypertension, PMHx.

"The mesenteric circulation consists of three primary vessels that supply blood to the small and large bowel: the celiac artery, superior mesenteric artery (SMA), and inferior mesenteric artery (IMA). Blood flow through these arteries increases within an hour after eating due to an increase in metabolic demand of the intestinal mucosa.Chronic occlusion of a single vessel allows collateral blood flow to compensate, thus symptoms do not typically present until at least two primary vessels are occluded." https://www.ncbi.nlm.nih.gov/books/NBK430748/

Collaterals between SMA and IMA near the splenic flexure (Meandering Mesenteric artery). There is also collateral between Celiac Artery and SMA (Pancreaticoduodenal arcade).

Lastly, I know that there is a 3-cm ectatic aorta found on CT, but an aortic aneurysm would not produce these symptoms. Even if you thought that the symptoms were due to the AAA, you could still get to the correct answer if you use fahmed14's reasoning.

honey-crusted lesion  Great explanation! There's also a slide about this in the 100 Anatomy Concepts pdf but doesn't go into as much detail as this explanation. Thanks!

 +1  (nbme24#33)

Papilloma virus causes Papillomatosis in infants. Growth in vocal cords= weak cry, hoarseness, stridor.



 +12  (nbme23#43)

Per UWORLD- Adenocarcinoma is associated w/ lung scarring related to granulomatous disease, old COPD (chronic) and damage due to recurrent pneumonia.


 +0  (nbme22#16)

Almost got tricked by this one because osteosarcoma also causes osteoblastic lesion. Osteosarcoma most commonly metastasizes to lungs though.

impostersyndromel1000  This was in pathoma, he said prostate cancer causes osteoblastic lesions and "the board examiners really want you to know that". also following the potential site of mets helps choose the answer

 +1  (nbme22#41)

Rupture of pulmonary blebs are a common cause of spontaneous pneumothorax in young adult males that are tall and thin. I know it's also associated with smoking, but gender and body habitus seemed like the more likely answer here since the patient is a young male.





Subcomments ...

submitted by bubbles(31),

Can someone could explain to me how this is unequivocally tuberous sclerosis despite NF-1 and Sturge-Weber also presenting with skin lesions, hypopigmented macules, and seizures?

And considering the negative family history, I would have assumed that a sporadic mutation (like SW) would be more likely...

cocoxaurus  This question was tricky! Tuberous sclerosis= Hypopigmented= Ash leaf spot (The skin lesion in NF is Hyperpigmented- Cafe au lait and in Sturge Weber it's a port wine stain (also not hypopigmented). I'm assuming that the SINGLE raised flesh colored lesion is a Hamartoma (The angiofibromas in NF1 are typically multiple). Although both Tuberous Sclerosis and Sturge Weber are both associated with seizures, I used all the other stuff to narrow it down to the correct answer. Also, don't forget that there is Incomplete penetrance and variable expressivity in Tuberous Sclerosis. So I think the lack of family history of "seizure or major medical illness" was there to throw us off. +10  
bubbles  Thank you! :) I thought I really knew my congenital disorders, so I was a little annoyed when they trotted this question out +1  


Everywhere I found (UpToDate and several papers) said the smoking is the biggest risk factor for spontaneous pneumothorax, with body habitus and gender being a lesser risk. Am I just completely misunderstanding the question?

imresident2020  Yes smoking is a risk factor but not the best option among the choices given. Check FA, it says that it occurs more in tall thin young males. Smoking isn’t even mentioned. Tall & thin males are more at risk because they have more negative intrapleural pressure. Check Uworld for this. +  
drdoom  You have to think about this using the concept of CONDITIONAL PROBABILITY. Another way to ask this type of question is like this: “I show you a patient with spontaneous pneumothorax. Which other thing is most likely to be true about this patient?” Said a different way: Given a CONDITION [spontaneous pneumo], what other finding is most likely to be the case? Still other words: Given a pool of people with spontaneous pneumothorax, what other thing is most likely to be true about them? In other words, of all people who end up with spontaneous pneumo, the most common other thing about them is that they are MALE & THIN. If I gave you a bucket of spontaneous pneumo patients -- and you reached your hand in there and pulled one out -- what scenario would be more common: In your hand you have a smoker or in your hand you have a thin male? The latter. +  
cocoxaurus  Rupture of pulmonary blebs are a common cause of spontaneous pneumothorax in young adult males that are tall and thin. I know it's also associated with smoking, but gender and body habitus seemed like the more likely answer here since the patient is a young male. +