Fibrous histiocytoma is a tumor composed of a mixture of fibroblastic and histiocytic cells. These lesions most often arise on the skin, but may rarely occur in soft deep tissues. The diagnosis of FH may be clinically difficult when the lesion is located in the deep tissues, and is frequently confirmed after local excision. The most important diagnostic necessity is the separation of this tumor from aggressive forms of fibrohistiocytic neoplasms. We present a unique case of malignant fibrous histiocytoma developing in left buccal mucosa very near to the surgical margin from which a benign fibrous histiocytoma of the mandible was excised 3 years earlier in a 31 year old female. Clinical and histopathological evidence were not sufficient to establish link between these two processes. This article aims to describe the case and discuss the findings.