USMLE Forums - View Single Post - Neurofibromatosis question and strange answer!
View Single Post
Old 06-11-2011
mle guy's Avatar
mle guy mle guy is offline
USMLE Forums Veteran
Steps History: 1+CK+CS+3
Posts: 264
Threads: 16
Thanked 362 Times in 167 Posts
Reputation: 372

Originally Posted by docoftheworld View Post
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?
Reply With Quote
The above post was thanked by:
rigbbm (07-21-2019)