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-   -   Neurofibromatosis question and strange answer! (https://www.usmle-forums.com/usmle-step-2-ck-forum/10152-neurofibromatosis-question-strange-answer.html)

docoftheworld 06-07-2011 02:15 PM

Neurofibromatosis question and strange answer!
 
A 23-year-old man known to have neurofibromatosis, type 1 (von Recklinghausen's disease), presents with a left lower quadrant abdominal mass and signs of neurologic deficits in his left leg. In the ensuing workup, it is determined that he has higher than normal values of catabolites of epinephrine and norepinephrine in a 24-hour urinary collection. He is currently normotensive. Before invasive steps are taken to biopsy and eventually remove his left lower quadrant abdominal mass, which of the following is the most appropriate next step in management?

A. CT scan of the head looking for meningiomas
B. MRI of his adrenal glands
C. MRI of the acoustic nerves
D. Radionuclide scans from the neck to the pelvis looking for extra-adrenal pheochromocytomas
E. Radiation therapy to the left lower quadrant abdominal mass

____________

The correct answer is B. The concern is that even though he is now normotensive, invasive steps might trigger a hypertensive crisis from the previously undiagnosed pheochromocytoma that he probably has. The presence of catabolites from epinephrine indicates that the tumor is in the adrenal glands, and not at an extra-adrenal site. Thus, the diagnosis of the pheochromocytoma can best be confirmed by MRI of the adrenals.

Meningiomas (choice A) and acoustic nerve tumors (choice C) occur in type 2 neurofibromatosis, not in type 1.

Looking for pheochromocytomas outside of the adrenal glands (choice D) would have been a good idea if only elevated catabolites of norepinephrine had been detected. The presence of high levels of epinephrine catabolites implicates the adrenal glands.

Radiation therapy (choice E) is a bad idea. Benign neurofibromas can be stimulated by radiation to undergo malignant transformation.


- --
Why not CT???? you have a focal neuro deficit ( I thought of meningioma) ... How come they ignored the leg thing!??!!? why did they even bring up the leg to start with? I realize its not extrapyramidal but the leg has something up with it ... what do u think?

1TA2B 06-10-2011 10:31 AM

Differential diagnosis of NF1!
 
I think the qustion is testing if we know phaeochromocytoma as its possible differential diagnosis!
Can be wrongly diagnosed!
Patient is in trouble if we miss this pre-op! May even die from hypertensive crisis!

See below

Conditions causing tumours confused with neurofibromas

1. Multiple lipomas – affect limbs and trunk
2. Bannayan–Riley Ruvalcuba syndrome – multiple lipomas, haemangiomas, macrocephaly pigmented patches on penis
3. Fibromatosis – multiple tumours of muscle, skin, bones and internal organs
4. Multiple endocrine neoplasia type 2B – phaeochromocytomas, mucosal neuromas, medullary carcinoma of thyroid, gastrointestinal ganglioneuromatosis, marfanoid habitus

jorgemorales 06-11-2011 04:42 AM

Quote:

Originally Posted by docoftheworld (Post 44862)
A 23-year-old man known to have neurofibromatosis, type 1 (von Recklinghausen's disease), presents with a left lower quadrant abdominal mass and signs of neurologic deficits in his left leg. In the ensuing workup, it is determined that he has higher than normal values of catabolites of epinephrine and norepinephrine in a 24-hour urinary collection. He is currently normotensive. Before invasive steps are taken to biopsy and eventually remove his left lower quadrant abdominal mass, which of the following is the most appropriate next step in management?

A. CT scan of the head looking for meningiomas
B. MRI of his adrenal glands
C. MRI of the acoustic nerves
D. Radionuclide scans from the neck to the pelvis looking for extra-adrenal pheochromocytomas
E. Radiation therapy to the left lower quadrant abdominal mass

____________

The correct answer is B. The concern is that even though he is now normotensive, invasive steps might trigger a hypertensive crisis from the previously undiagnosed pheochromocytoma that he probably has. The presence of catabolites from epinephrine indicates that the tumor is in the adrenal glands, and not at an extra-adrenal site. Thus, the diagnosis of the pheochromocytoma can best be confirmed by MRI of the adrenals.

Meningiomas (choice A) and acoustic nerve tumors (choice C) occur in type 2 neurofibromatosis, not in type 1.

Looking for pheochromocytomas outside of the adrenal glands (choice D) would have been a good idea if only elevated catabolites of norepinephrine had been detected. The presence of high levels of epinephrine catabolites implicates the adrenal glands.

Radiation therapy (choice E) is a bad idea. Benign neurofibromas can be stimulated by radiation to undergo malignant transformation.


- --
Why not CT???? you have a focal neuro deficit ( I thought of meningioma) ... How come they ignored the leg thing!??!!? why did they even bring up the leg to start with? I realize its not extrapyramidal but the leg has something up with it ... what do u think?

Hey, could be that the tumor is compressing the lumbar plexus or one of its branches. It could also be locally invasive, given that 10% of pheochromocytomas are malignant.

mle guy 06-11-2011 11:34 AM

Quote:

Originally Posted by docoftheworld (Post 44862)
A 23-year-old man known to have neurofibromatosis, type 1 (von Recklinghausen's disease), presents with a left lower quadrant abdominal mass and signs of neurologic deficits in his left leg. In the ensuing workup, it is determined that he has higher than normal values of catabolites of epinephrine and norepinephrine in a 24-hour urinary collection. He is currently normotensive. Before invasive steps are taken to biopsy and eventually remove his left lower quadrant abdominal mass, which of the following is the most appropriate next step in management?

A. CT scan of the head looking for meningiomas
B. MRI of his adrenal glands
C. MRI of the acoustic nerves
D. Radionuclide scans from the neck to the pelvis looking for extra-adrenal pheochromocytomas
E. Radiation therapy to the left lower quadrant abdominal mass

____________

The correct answer is B. The concern is that even though he is now normotensive, invasive steps might trigger a hypertensive crisis from the previously undiagnosed pheochromocytoma that he probably has. The presence of catabolites from epinephrine indicates that the tumor is in the adrenal glands, and not at an extra-adrenal site. Thus, the diagnosis of the pheochromocytoma can best be confirmed by MRI of the adrenals.

Meningiomas (choice A) and acoustic nerve tumors (choice C) occur in type 2 neurofibromatosis, not in type 1.

Looking for pheochromocytomas outside of the adrenal glands (choice D) would have been a good idea if only elevated catabolites of norepinephrine had been detected. The presence of high levels of epinephrine catabolites implicates the adrenal glands.

Radiation therapy (choice E) is a bad idea. Benign neurofibromas can be stimulated by radiation to undergo malignant transformation.


- --
Why not CT???? you have a focal neuro deficit ( I thought of meningioma) ... How come they ignored the leg thing!??!!? why did they even bring up the leg to start with? I realize its not extrapyramidal but the leg has something up with it ... what do u think?

Adrenal masses are not palpable. how can pheochromocytoma be palpable? That mass could be something else and CT/MRI abdomen should better visualise it?

1TA2B 06-11-2011 03:20 PM

Abdominal neoplams in NF-1! May well be one of them-abdominal mass!
 
http://radiographics.rsna.org/conten.../T1.medium.gif

mle guy 06-11-2011 11:34 PM

Quote:

Originally Posted by 1TA2B (Post 45696)

So its most probably a neurofibroma than a pheochromocytoma and for that we will need CT/mri abdomen

samstar 06-12-2011 01:51 AM

men type 2
 
Quote:

Originally Posted by docoftheworld (Post 44862)
A 23-year-old man known to have neurofibromatosis, type 1 (von Recklinghausen's disease), presents with a left lower quadrant abdominal mass and signs of neurologic deficits in his left leg. In the ensuing workup, it is determined that he has higher than normal values of catabolites of epinephrine and norepinephrine in a 24-hour urinary collection. He is currently normotensive. Before invasive steps are taken to biopsy and eventually remove his left lower quadrant abdominal mass, which of the following is the most appropriate next step in management?

A. CT scan of the head looking for meningiomas
B. MRI of his adrenal glands
C. MRI of the acoustic nerves
D. Radionuclide scans from the neck to the pelvis looking for extra-adrenal pheochromocytomas
E. Radiation therapy to the left lower quadrant abdominal mass

____________

The correct answer is B. The concern is that even though he is now normotensive, invasive steps might trigger a hypertensive crisis from the previously undiagnosed pheochromocytoma that he probably has. The presence of catabolites from epinephrine indicates that the tumor is in the adrenal glands, and not at an extra-adrenal site. Thus, the diagnosis of the pheochromocytoma can best be confirmed by MRI of the adrenals.

Meningiomas (choice A) and acoustic nerve tumors (choice C) occur in type 2 neurofibromatosis, not in type 1.

Looking for pheochromocytomas outside of the adrenal glands (choice D) would have been a good idea if only elevated catabolites of norepinephrine had been detected. The presence of high levels of epinephrine catabolites implicates the adrenal glands.

Radiation therapy (choice E) is a bad idea. Benign neurofibromas can be stimulated by radiation to undergo malignant transformation.


- --
Why not CT???? you have a focal neuro deficit ( I thought of meningioma) ... How come they ignored the leg thing!??!!? why did they even bring up the leg to start with? I realize its not extrapyramidal but the leg has something up with it ... what do u think?

i think the question wants u to think about men type 2 b and not meningioma..that is why the case describes both von Recklinghausen's disease and increased catecolamines ..in this case we need to isolate the tumor ...so the MRI of the abdomen...

Up to 36% of PHEOs are malignant.
5 The annual
cumulative incidence of PHEOs/PGLs is reported
as approximately 3-8 per 10
6 population.8 Although
MEN2-associated PHEOs are usually benign, if left

untreated they can be lethal.http://hormones.gr/pdf/Diagnosis%20o...20syndrome.pdf

Habenula 06-21-2013 09:41 AM

A meningioma cannot have focal neurologic deficit. The questions is testing whether you know that neurofibromatosis is associated with pheochromocytoma and that it should be looked for preoperatively to avoid hypertensive crisis. This focal neurologic deficit could be due to that mass in the abdomen


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