Clinico-pathologic correlations of myofibroblastic tumors of the oral cavity: 1. nodular fasciitis

BACKGROUND: Nodular fasciitis (NF), a soft tissue lesion mainly composed of myofibroblastic cells, is well documented in various body locations however, in the oral cavity it is rare. The NF has non-specific histologic characteristics that might result in misdiagnosis and mistreatment. The aim of the study was to analyze clinico-pathologic correlations of NF occurring in the oral cavity. METHODS: A total of 36 cases of oral NF were analyzed including review of the English language literature and five new cases from our files. RESULTS: Oral mucosa NF was found to peak in the fourth and fifth decades, which is a decade later than NF occurring in other sites of the body. The most common locations were the buccal mucosa (52.8%) and the lips (16.7%). Duration of lesions ranged from 3 days to 2 years, with approximately 61% being present for more than a month, which is longer than the duration of NF from other body locations. Histologically, oral NF showed varying degrees of cellularity and frequently contained myxomatous areas, and often demonstrated local infiltration into adjacent tissues. However, the myofibroblastic, spindle-shaped lesional cells were uniform and lacked any major signs of atypia. Mitotic figures, characteristically abundant in NF lesions throughout the body, ranged from absent to moderately high in oral NF cases. Treatment modality of choice was complete surgical excision. Recurrence was reported for only one case. Extensive, mutilating surgical procedures for oral mucosa NF are unnecessary, since lesions resolve even when surgical margins are partly involved. CONCLUSIONS: The NF should be included in the clinical differential diagnosis of superficial and deep soft tissue masses of the oral cavity, especially of the buccal mucosa. Histopathologically, NF should be differentiated from other spindle cell lesions, mainly myofibroma, neurofibroma, fibrosarcoma, solitary fibrous tumor, fibromatosis and fibrous histiocytoma.