In my last report there may have been some confusion, partly from translation, regarding the arachnoid cyst versus tumor cyst.
Now having seen the images, I believe I much better understand the situation. On my review, the April 2009 MRI does not appear all that different compared to the February 2009 MRI. There continues to be:
(a) a right temporal, almost 5 cm, ovoid arachnoid cyst, adjacent to the right optic nerve and chiasm, and (b) a 3+ cm cystic mass (tumor) with the cyst, located eccentrically to the right, with heterogeneous enhancement with gadolinium, and tortuous optic nerves anteriorly.
Per the May note, ophthalmological evaluation on April showed: “picture of slight reduction in visual acuity of the right eye and severe hypovision of the left eye with slight reduction of the bilateral visual field in the temporal areas in chiasmatic-hypothalamic glioma and NF-1,” and MRI showed “presence of a big expansive lesion in sellar and oversellar region, extremely not homogeneous and mainly cystic that remodels the ethmosphenoid region resulting in an omega-shaped appearance…andpresence of right temporopolar arachnoid cyst.”
Thus, after seeing the images myself, it appears that the arachnoid cyst has not changed that much, if at all, and probably has little impact or effect at this time. Moreover, the optic chiasm tumor appears to have changed little, too. And, I can only surmise that the neurosurgeon may have said either:
(1) the right temporal arachnoid cyst should be drained now before chemotherapy;
(2) the right temporal arachnoid cyst will need to be drained after completion of chemotherapy;
OR (3) the cystic contents of the optic chiasm lesion/tumor should be drained before chemotherapy.
Allow me to elaborate on each of these possibilities 1-3 below:
(1) If the arachnoid cyst has enlarged (although I really don’t believe the arachnoid cyst had increased from my best comparison of images via the Internet) and is truly exerting compression toward the visual apparatus (again, I don’t think such is the case), then yes, surgery to decompress or remove the cyst is reasonable and medically indicated. But again, I don’t think the arachnoid cyst has changed much, and then no surgery is warranted now.
(2) If the surgeon feels that the arachnoid cyst will simply need to be drained following completion of chemotherapy, because of its proximity to aforementioned structures, then no, I disagree. The operation is not essential and will not necessarily be required after chemotherapy, unless the arachnoid cyst enlarges notably. Such cysts are common in children with neurofibromatosis 1 and most often stable, not changing.
(3) If the surgeon and oncologist both believe the cystic component of the tumor needs to be performed prior to starting chemotherapy, such would be reasonable, though high risk, in the hands of the best pediatric neurosurgeons, to debulk or minimize the lesion prior to chemotherapy, if chemotherapy must be started.
Again, does chemotherapy need to be started now? Not necessarily, but possibly. I would maintain strongly my previous recommendation about whether to start or not start chemotherapy. If the child has clear significant and notable decline of visual function by fields (i.e., loss of fields) or acuity (i.e., acuity less than the United States measurement of 20/40-20/50 OU), then yes, I would definitely commence chemotherapy. It seems by the ophthalmology report that there may be visual field loss or possibly acuity decline, and if such is definitely true, obvious, and clear, then yes, chemotherapy would be appropriate. Again, if the solid (not cystic) portion of the tumor on MRI were much greater than previous, say 25-33% bigger, then yes, we would start chemotherapy. But, I do not believe the size of solid tumor has changed significantly. We would not be scared into starting chemotherapy just because the child has tortuous optic nerves or a mass (even if cystic) at the chiasm, both frequent findings in many children with neurofibromatosis.