Oral fibrolipoma in dogs: Retrospective case series study and comparative review

Fibrolipoma is defined as a typical lipoma transected by variable amounts of paucicellular and collagenous fibrous components. Oral and lingual fibrolipomas are well-recognized histological entities in human medicine that are slightly more prevalent in females, occur most commonly after the fourth decade, and arise from the buccal mucosa. The documentation of this neoplasm in the oral cavity is lacking in veterinary medicine. Through a multi-institutional retrospective compilation of cases submitted to diagnostic pathology services, here we describe the clinical and pathologic features of oral fibrolipomas in dogs. A total of 112 cases of oral fibrolipomas in dogs were retrieved. The mean age was 10.1 years (range 2-16 years, ±2.63 years standard deviation), with an average tumor size of 1.7 cm (range 0.2-8 cm, ±1.1 cm standard deviation). The most common location was the tongue (57.1%, 64/112), followed by the buccal mucosa (15.2%, 16/112), sublingual area (8.0%, 9/112), gingiva and lip (4.5%, 5/112 each), and palate (1 case). The anatomical location of oral fibrolipomas only differed significantly among the dog breeds (P < .001) but not among sex, age, anamnesis, or reason for submission. The tumor was most commonly reported in males (69.7%, 78/112), and in 62.5% (70/112) of the cases, the tumor was an incidental finding. Fibrolipoma should be considered a differential diagnosis when considering benign lingual and other oral soft tissue masses in dogs.