A substantial retrospective study evaluated 297 surgically removed feline oral cavity lesions submitted to a pathology laboratory service in Lisbon, Portugal, over a 6-year period. Most samples were incisional (86.2%) or punch biopsies (1.7%), and 12.1% were excisional biopsies.
Overall, 64.4% of biopsies were from cats ≥7 years of age and 31.9% were from cats 7 months to 6 years of age. The major anatomical regions biopsied were the gingiva (43.1%), oral mucosa (16.2%), tongue (10.8%), lips (8.1%), and palate (5.7%). Other sites included the oropharynx, maxillary bone, salivary glands, floor of the mouth, and tonsils. Histopathology revealed an inflammatory process in 63% of cases and a neoplastic process in 37%. The proportion of neoplastic cases increased with age and accounted for most lesions in cats ≥11 years of age. However, even in young cats (ie, 7 months to 2 years of age) and young adult cats (ie, 3-6 years of age), neoplastic lesions were seen frequently, representing 5.4% and 16.7% of biopsies in cats of those ages, respectively.
Of the 187 cases of inflammatory disease, 62% (n = 116) were feline chronic gingivostomatitis (FCGS), with the most common sites affected being the gingiva (n = 66), oral mucosa (n = 22), and oropharynx (n = 12). FCGS was seen in cats of all ages but was most common in male cats 7 months to 10 years of age. Eosinophilic granuloma complex (EGC) lesions accounted for 17.6% (n = 33) of inflammatory lesions and comprised 23 eosinophilic ulcers and 10 eosinophilic granulomas. The most common sites of EGC lesions were the lips (n = 12) and tongue (n = 5). Other inflammatory lesions included nasopharyngeal polyps, nonspecific stomatitis, and gingival hyperplasia.
Of the 110 neoplastic lesions, 90 (81.8%) were classified as malignant, and overall, squamous cell carcinoma (SCC) was the most common tumor (n = 49; 44.5%). The gingiva (n = 18) and mandible (n = 10) were the most common sites affected by SCC, and most of these cats were ≥11 years of age. Other neoplastic lesions included undifferentiated tumors (17.3%), odontogenic tumors (8.2%), peripheral nerve sheath tumors (8.2%), adenocarcinomas (5.4%), and fibrosarcomas (4.5%).