Post-traumatic spindle cell nodule misdiagnosed as a herniation of the buccal fat pad

We studied a quasi-neoplastic lesion that developed in the oral mucosa secondarily to trauma. The female patient, 2 years of age, presented with a rapidly growing nodule and the lesion was diagnosed as a herniation of the buccal fat pad. Following partial resection, no recurrence was seen. The ulcerated polypoid mass was composed of compact spindle-cell proliferation with invasion of underlying muscle and fat. Atypical stromal cells were present in the myxoid areas. The surface edematous stroma contained abundant granulation tissue-type vascularity and a mixed population of chronic inflammatory cells. On immunohistochemical study, the spindle cells were consistent with myofibroblasts. The morphologic features, proliferating cell type, and benign clinical course are identical to the post-operative spindle cell nodules that occur in the genitourinary tract.