Malignant tumors rarely arise in jaw cysts. We report a case of squamous cell carcinoma arising in a nasopalatine canal cyst. A 56-year old man presented with swelling in the labial gingiva at the middle of the maxilla. Oral examination showed a thumb-tip sized swelling with a smooth surface and normal color. Radiographic examination revealed a round translucent image measuring 25mm in diameter in the middle of the maxilla. This image was clearly demarcated. Under general anesthesia, ablation of the cyst was performed for a diagnosis of nasopalatine canal cyst. During operation, frozen section diagnosis was performed and revealed squamous cell carcinoma in this cyst. After operation, chemotherapy (CDDP+5 FU) and radiation treatment (50Gy) were performed. The patient has a good prognosis, with no evidence of local recurrence or metastasis.
