“When is neuroblastoma the answer for USMLE?”

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[00:00:00]What is neuroblastoma? The answer for your USMLE attending at those questions wrong. Okay. So, do you guys know the classic location for neuroblastoma if you're forced to choose?

[00:00:11]It's going to be the adrenal medulla.

[00:00:13]Okay, it secretes catecholamines. You can memorize it as the pediatric version of pheo.

[00:00:19]Okay, pheochromocytoma in adults, neuroblastoma in kids. Now, those of you who are very astute, you know that neuroblastoma is actually they can form anywhere in the median midline, the median sympathetic chain. There's an NBME question where they give it to you in the posterior mediastinum.

[00:00:38]Okay, but adrenal medulla about half the time. Now, do you know how you diagnose neuroblastoma?

[00:00:46]The first step?

[00:00:48]So, it's going to be urinary HVA and VMA, homovanillic acid and vanillylmandelic acid. Urinary metanephrines is wrong, that's going to be for pheochromocytoma. They ask that distinction on USMLE. Do you know any other symptoms that you can get in neuroblastoma?

[00:01:07]I guess just any symptoms at all.

[00:01:10]So, hypertension makes sense if it's secreting catecholamines. Only about half of questions asked per my observation. And you can get something fancy called opsoclonus myoclonus syndrome. It just means dancing eyes and muscle jerks, but you got to know it.

[00:01:24]You can also get something weird. You can get violaceous eyelids due to orbital metastases. It almost sounds like heliotrope rash in dermatomyositis.

[00:01:35]So, do you guys know any gene associations with neuroblastoma?

[00:01:42]So, the N-myc gene.

[00:01:45]And what about your pheochromocytoma tangentially?

[00:01:50]That's going to be the RET gene. Okay, MEN 2A, MEN 2B, obviously not mandatory, but those are some classic gene associations. Now, the student says they're getting questions wrong.

[00:01:59]Classically, I'll give you the high yield differentials here. Now, neuroblastoma is going to be a kid classically 2 to 10 years old with a midline mass with the symptomatology we talked about. If they give you a kid 2 to 10 years old who has a painless flank mass, that's not going to be neuroblastoma.

[00:02:16]What's that going to be?

[00:02:19]Well, that's going to be Wilms tumor till proven otherwise. Okay. Well, if you have, let's say, a neonate, let's say neonatal boy, and he has a midline abdominal mass, what's that going to be till proven otherwise?

[00:02:36]That's going to be posterior urethral valves with a distended bladder.

[00:02:40]Obviously, too young for neuroblastoma.

[00:02:43]So, when you see these questions, student says they're getting them wrong.

[00:02:46]Wilms tumor, posterior urethral valves, neuroblastoma.

[00:02:50]Obviously, pheochromocytoma. We said that's adults. So, that's the easy way to differentiate these.