Nodular fasciitis is defined by the World Health Organization as a benign proliferative fibroblastic lesion. It was first described in 1955 by Konwaler et al. and also known as “nodular pseudosarcomatous fasciitis” and “infiltrative fasciitis”, which reflect the lesion’s rapid growth, dense cellularity, alarming mitotoic activity and lack of circumscription. Here, we report a case of nodular fasciitis, which appeared as subcutaneous mass of right perizygoma area in 40-year-old Korean female. She had no history of trauma or cosmetic surgery related with the lesion. She disclosed that the mass grew rapidly for last 2 months. Computed tomography showed relatively well-defined spherical mass with 1.2 cm in diameter. Under local anesthesia the mass was resected by intraoral approach. The histological examination revealed a relatively poor-dermacated mass with high cellularity, which was composed with infiltrative spindle-shaped cells without accompanying inflammatory reactions. The tumor cells were partially positive for α-smooth muscle actin and β-catenin, but negative for cytokeratin AE1/3, S-100, desmin, and CD34. Therefore, the lesion was pathologically diagnosed as nodular fasciitis. Although nodular fasciitis is known to pseudosarcomatous benign reactive lesion, the clinician need to follow up the patient periodically. The reasons are as follows; Nodular fasciitis may accompany nuclear accumulation of β-catenin, which imply neoplastic process rather than reactive process of the lesion. Moreover, it has many histological similarities with inflammatory myofibroblastic tumor which have malignant transformation tendency. Further research for mesenchymal tumor could help our understanding for the disease entity of nodular fasciitis

• 양동현(연세대학교 치과대학 구강병리학교실, 구강종양연구소) | Dong Hyun Yang
• 차인호(구강악안면외과학교실) | In Ho Cha
• 양우익(연세대학교 의과대학 병리학교실) | Woo Ik Yang
• 김진(연세대학교 치과대학 구강병리학교실, 구강종양연구소) | Jin Kim
• 육종인(연세대학교 치과대학 구강병리학교실, 구강종양연구소) | Jong In Yook
• 김현실(연세대학교 치과대학 구강병리학교실, 구강종양연구소) | Hyun Sil Kim correspondence