Cysts are a very rare cause of masses in dogs. Jess had an unusual swelling on the side of the face, just below her eye, which was reported as a cyst on aspirates and biopsy. Her vets had sent her for a CT scan of her face, which showed the cyst had eroded part of her upper jawbone. Loss of bone is normally only seen with jaw tumours, but the position of the swelling and the benign feature of the bone loss, were consistent of a very rare condition called ‘dacryops’, the cause of which is unknown in people and animals, but it may be a cyst of lacrimal gland origin. Jess’s cyst was different from many in the literature, as it had not fully invaded the bone. However, it had invaded just enough bone to be separated from one of the largest artery-vein complexes of the head, the infraorbital vessels, by one layer of connective tissue. Furthermore, the cyst had removed just a small part of the tunnel of bone the vessels travel in.

 

In the CT images, you can see the images are displayed so that one shows up the cyst and its outline, and the other highlights the bone. Comparing the two sides, it is possible to see where the bone her been partially eroded by pressure from the cyst. 

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Damage to the vessels during dissection ran the risk of retraction of bleeding vessels into the bone tunnel and severe haemorrhage.  Plans were made for how to manage marked haemorrhage including access to blood for transfusion and plans for an alternative surgical approach to the vessels if they bled. A surgical approach was made from the skin of the face and the cyst carefully separated from surrounding tissue. Fortunately, the cyst was successfully separated from the underlying blood vessels with no damage and removed in its entirety. 

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Jess made a good recovery from surgery, helped by her feline buddy!