We present the medical history of a 61 year old male patient with a many years persiting swelling in the depth of the left cheek anteior of m. masseter that was actually growing slowly without pain. The patient could not remember any accident or surgery in this area. A possible systemic inflammatory cause was also not present. Presurgical performed MRI-scan and OPTG were even more not able to give hints to etiology. Under suspicion of a chronic sialadenitis of a small salivary gland the mass was removed by an transoral approach after splinting Stenon duct. The histopathologigal reprocessing revealed a high-grade fibrosis with particular xanthogranulomatous inflammation and herotopic ossifcation. Salivary gland tissue or mykobacterial inflammation components were not detectable. Further wound healing of the patient was within normal limits. The presented case shows that not only frequent beningn lesions but also rare lesions of the cheek have to be considered in differential diagnosis. Like in this case sometimes etiology stays indeterminate and diagnosis emerges by exclusion. Keywords: xanthogranulomaous inflammation, heterotopic ossification, swelling of the cheek with unknown etiology