NBME 23 Retroperitoneal fibrosis (NBME Answers)

NBME 23 Answers

nbme23/Block 1/Question#42 (reveal difficulty score)
A 68-year-old woman comes to the office ...
Retroperitoneal fibrosis 🔍 / 📺 / 🌳 / 📖
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submitted by ∗sajaqua1(607)

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The patient has a prior history of hysterectomy with bilateral salpingo-oophorectomy, and received external beam radiation to the pelvis. The patient now displays hydronephrosis and hydroureter, with distal ureteral narrowing bilaterally. The likeliest option is that we are seeing adhesions from previous surgery constrict the ureters, causing this.

E) Urothelial carcinoma (also called transitional cell carcinoma) is also a possibility. What makes this unlikely is the location: bilateral. The prior hysterectomy and bilateral salpingo-oophorectomy would leave scar tissue on both sides of the body, but the odds of urothelial carcinoma arising bilaterally are very slim.

A) The patient had a hysterectomy, so the odds of recurrent cervical carcinoma are also incredibly low. C) and D) Urethral condyloma and urethral transitional cell papilloma are in the wrong location to account for bilateral urethral narrowing with hydroureter.

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stinkysulfaeggs Great explanation - just one addition. The retroperitoneal fibrosis could also be a direct consequence of the external beam radiation. It's linked to both causes. Either way, it's a better fit than urothelial carcinoma (in retrospect). +17

spow Why would the onset be 15 years later though? +3

drzed I was thinking the same thing @spow. I had put urothelial carcinoma, thinking that a field defect would result in bilateral tumor. +3

yesa My understanding is the cancer risk with radiation is late-onset, a decade or more after the fact +

fatboyslim Why does she have increased daytime and nighttime urination? I couldn't figure that part out. +

weirdmed51 @fatboyslim not relevant +

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submitted by ∗colonelred_(124)

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The patient had a total hysterectomy so a recurrence of cervical cancer is virtually not possible. Retroperitoneal fibrosis commonly results from radiation therapy to the pelvis, which can lead to bilateral hydronephrosis.

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submitted by ∗mousie(272)

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Why not urothelial carcinoma? Or how did you rule it out? I was thinking radiation would increase risk for future CA...

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submitted by ∗temmy(152)

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What of if the cancer is a urothelial cancer in the bladder due to radiation therapy. would it not cause similar signs

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charcot_bouchard Chance of bilateral ureteral ca is very rare. Also preincipal r/f for transitional cell ca is Smoking not radiation +

peridot Hi temmy, yes it sounds like it would. There is a similar question from NBME 21 for those who have already taken that one (https://nbmeanswers.com/exam/nbme21/744). In that one, it's cancer in the uterus instead of bladder, but it's the same concept - the cancer can spread from the uterus into the bladder, or compress on the bladder, leading to bilateral hydroureter and hydronephrosis. So basically the takeaway point from that question and this question is that we learned a few things that can lead to bilateral hydronephrosis and hydroureter: 1. bladder cancer 2. uterine cancer 3. surgical and radiation treatment of cancer in that region, leading to bilateral fibrosis of the ureters. +2

peridot Whoop just realized that urothelial carcinoma is a possible answer choice here. Well, I'm lost.... :x +

abcdefbhiximab Urothelial carcinoma presents as painless hematuria with risk factors (i.e. smoking, aniline dyes) +2

mutteringly In addition, the wording says "distal ureteral narrowing" which wouldn't happen with bladder cancer +1

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