Magnetic resonance imaging features of zygomatic lipomatosis in a mixed‐breed dog

A 4-year-old, male, entire, mixed breed dog presented with right-sided periorbital swelling and exophthalmos. Magnetic resonance imaging of the head revealed severe enlargement of the right zygomatic gland, which resulted in anterior displacement of the right eye and protrusion of the zygomatic gland into the oral cavity. The enlarged gland showed an increased T2 signal intensity and was traversed by multiple septae, which partially suppressed after fat saturation. The gland was surgically removed using a lateral orbitotomy. Histopathology revealed a lipomatosis of the salivary gland. Zygomatic lipomatosis occurs rarely in dogs, and should be considered as a differential diagnosis in cases of unilateral gland enlargement with fat infiltration on magnetic resonance imaging. This case highlights the usefulness of magnetic resonance imaging, including fat-suppressed sequences, for the diagnosis of extracranial diseases.