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This patient had a mass in the orbit that was causing

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discomfort along the lateral orbital

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wall on the left side.

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As we scroll through this case, we note that the

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lacrimal gland is enlarged on the left

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side compared to the right side.

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This lesion extends posteriorly in the extraconal space

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and extends even to the orbital apex.

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As we come further

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inferiorly, we note a discrepancy in the appearance of

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the pterygopalatine fossa on the left

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side compared with the right side.

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The pterygopalatine fossa is located posterior

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to the posterior wall of the maxillary antrum.

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Normally, it contains fat and the pterygopalatine ganglion.

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Here we see the fat and we see a little bit of the ganglion.

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On the left side,

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we see enlargement of the pterygopalatine fossa and

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loss of the normal fat of the pterygopalatine fossa.

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How did this tumor get into the pterygopalatine fossa?

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What one sees here is one of the egresses from the

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pterygopalatine fossa, and that is the inferior

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orbital fissure. It leads into the orbit.

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The lateral egress from the pterygopalatine fossa

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is called the pterygomaxillary fissure.

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It leads to the muscles of mastication.

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And although we see nice definition

1:49

of the muscles of mastication

1:53

on the right side, we lose that definition and the fat

1:58

drains between the muscles on the left side,

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indicating infiltration.

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Medially, one can see that from the pterygopalatine

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fossa, one can enter the nasal cavity.

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This medial opening is called the sphenopalatine foramen

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and it, too, is one of the exits from the pterygopalatine fossa

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through which cranial nerve five branches may enter.

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The pterygopalatine fossa also has

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a posterior exit.

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And for that, I'm going to zoom in just a little bit more.

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This posterior entrance is the foramen rotundum

2:58

and it is one of the exits from the pterygopalatine fossa of the

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second division of the fifth cranial nerve. You notice

3:07

that it is enlarged compared to the

3:10

contralateral foramen rotundum.

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Finally,

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I want to demonstrate another of the inferior exits of

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the pterygopalatine fossa, this is the vidian canal

3:27

through which the vidian nerve runs. You notice that it

3:31

has some fat within the canal, as well as we

3:35

see the fat in the pterygopalatine fossa.

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Here we have our sphenopalatine foramen going into

3:40

the nasal cavity. We have our pterygomaxillary fissure

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going into the masticator space, and we see enlargement

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of the opening of the vidian canal and it

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is filled with soft tissue. That's tumor.

3:55

So, let's get back to the original lesion which arose

4:00

from the lacrimal gland. And for that, we have

4:03

de-zoom. As I mentioned previously,

4:07

the lacrimal gland can be considered a type of

4:12

salivary gland with respect to the different

4:14

pathologies that affect it.

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The most common malignancy of the salivary glands is

4:22

adenoid cystic carcinoma.

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Adenoid cystic carcinoma

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has a 50%-60% rate of perineural spread.

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What we've seen here is a lesion of the lacrimal gland

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that has spread posteriorly via the second division of the fifth

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cranial nerve to infiltrate the pterygopalatine

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fossa and all of its nerve branches.

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So I would have come down hard on adenoid

4:48

cystic carcinoma of the lacrimal gland.

4:52

I would have been wrong.

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This ended up being a lymphoma.

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The types of lymphoma that can affect the lacrimal

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gland are most commonly the non-Hodgkin's B-cell type,

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of which mucosa-associated lymphoid tissues

5:09

or MALT lymphomas, are the most common.

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95% of patients who have orbital lymphoma will

5:16

have systemic manifestations of the lymphoma.

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Lymphoma of the orbit most commonly affects the

5:22

lacrimal gland, but it can also affect the conjunctiva,

5:26

the eyelid, and the bones.

5:28

So this was a fakeout for me going down the route of

5:32

adenoid cystic carcinoma based on the perineural

5:35

spread, but we do know that lymphoma as well can cause

5:38

perineural spread.

5:39

In this case, infiltration along the pterygopalatine fossa.