Spindle cell lipoma in the gingiva of a dog: a case report

Spindle cell lipoma is a benign lipomatous tumour that mainly occurs in the subcutis of the head, neck, and shoulder in elderly men. Oral spindle cell lipoma is extremely rare in all species, and no cases have been reported in veterinary medicine. A 10-year-old male Maltese dog was presented for evaluation of a whiteto cream-coloured gingival mass. Microscopically, the mass was composed of mature fat cells and spindle cells containing thick fibrocollagenous bundles. The neoplastic cells showed positive immunoreactivity to vimentin and CD34. Based on the clinical and histopathological findings, spindle cell lipoma of the gingiva was diagnosed. Further immunohistochemical analysis revealed that both adipocytes and spindle cells exhibited positive reactions to oestrogen receptors α and β. These findings demonstrate the clinical, morphological, and immunohistochemical characteristics of an oral spindle cell tumour. The potential role of sex steroid hormones in the pathogenesis of this tumour is also discussed.