Sphenoid Sinus: Mucous Retention Cyst vs. Mucocele (correction, Slide 5)
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Sphenoid Sinus: Mucous Retention Cyst vs. Mucocele (correction, Slide 5)

January 7, 2020


Hi, I’m James Smirniotopoulos and this is a MedPix video for case 14328 This is also a case of the week and you
can earn AMA category 1 CME credit from our website: rad.usuhs.edu/medpix We have no significant financial nor
other conflict of interest disclosures. This
case was contributed by Stephen J Goldstein from the University of Kentucky We have a 44-year-old woman was symptoms of sinusitis who was evaluated by CT in Jan this axial CT with bone windows demonstrates
mucosal thickening and some fluid accumulation within the
sphenoid sinus. We can also see that this sinus does not have air and is completely opacified and very
homogeneous suggesting it is filled with fluid. The sinus also has slightly convex margins. The sphenoid sinus is the third to aerate (pneumotize), and the frontal is usually last and is not
always aerated and often small. In about eighty percent of cases, the sphenoid sinus will havel have a bone septation and in 20 percent will have two septations.
The sphenoid sinuses open or darin into the posterior nasal cavity, just above the call Wayne a in this
pheno mortal recess usually medial to the superior nasal
turbinate. Common lesions of the sphenoid sinus include sinusitis as well as extension a pituitary adenoma, inverting papilloma, metastatic disease &
Lymphoma. In this case, the lesion is so very homogeneous sugesting a fluid-filled sinus cavity. Is this a “mucous retention
cyst”? Or, is it a mucocele? This is a very
common and often confusing question. A mucous retention
cyst is obstruction of a single paranasal
sinus with retained secretions. The prevalence is a little bit less than
10 – as found on panoramic dental films in otherwise normal patients. But, up to 50% on CT scans done for orbit or sinus symptoms show a mucocle. Most mucous retention cysts are usually without symptoms and spontaneously regress. They are typically lined by respiratory
epithelium which may become modified Retention cysts are most common in the maxillary sinus and least commonly in the sphenoid signs.
As an example, we show a CT image of an asymptomatic maxillary sinus mucous
retention cyst. We can see that the lesion is relatively homogeneous and
water like in its attenuation. We can see that the sinus cavity is not
remodeled by the cyst and retains its normal shape as shown on the coronal image. Using bone window display, we can see the
classic dome-shaped appearance of the upper
margin of the mucous retention cyst and, again,
there is no bony remodeling. Mucus retention cysts
are most common in the maxillary antrum and they are very prevalent and they
have been observed to appear and resolve without therapy. When they do
become symptomatic the options should include watchful waiting as well as
treatment for the underlying sinusitis. So our patient actually has a mucocele.l
A mucocele is also fluid filled, and lined by respiratory epithelium. The fill with mucous secretions from the lining. The sinus drainage openind or “ostium” is obstructed and the sinus cavity
cannot drain, accumulating fluid. This results in secondary expansion of the sinus cavity with expansile bony remodeling. Histology is often nonspecific because of the chronic nature of the obstructed
sinus opening. the most common location for an obstructed sinus and mucocele is in the frontal sinus; and, the least common location is in the
sphenoid sinus. The sphenoid represents less than 10
percent of all mucoceles. Now our patient returned for a follow-up
visit in August because of worsening symptoms We can now see that there has been a progressive change with enlargement of the sphenoid sinus cavity. Further, there is high attenuation
material accumulated within the sinus cavity. and we are not able to clearly see the bony margin of the sinus wall along the left lateral maring – adjacent to the left middle cranial fossa in the area of the cavernous sinus on this agile image we can see the mass
homogeneous fluid signal we can see the inferior, the middle, and the superior nasal turbinates. Just as a reminder, this is the location for the sphenoid
sinus ostium just medial to the superior nasal
turbinate. Our patient has now a new neurologic problem – an afferent
pupillary defect in her left eye. If we carefully compare the
original image from January, back then we could see the lateral bone margin. However, if we look at the current study image from August, maybe the mass i snow
expanded and we have lost the bony detail from the
lateral margin on the left side of the sinus if we look more carefully at the MR scan,
which we have already seen, we can see the masshas fluid signal and we
can also see the internal corroded flow void in the cavernous sinus has a a normal appearance on the right side
but we do not see a corresponding flow void on the left side and we have lost the sclerotic bone margin. Now the
differential diagnosis would include, in addition an ossifying fibroma, inverting papilloma, square a Miss carcinoma in base a bit to
a teary-eyed no mccord Alma in metastatic disease for a lesion
involving the sphenoid bone however in our case the case is
homogeneous and it was surgically treated with
drainage up mucus eel so again this has been a case about sphenoid sinus mucus seal complicated by enlargement and erosion
and scold a sin invasion involving the cavernous sinus Thank you very much for your attention
I’m Jim Smirniotopoulos and I approve this message.

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