Intraosseous vascular malformation, a representative vascular disease, rarely occurs in the oral and maxillofacial region, especially the maxilla. An 18-year-old female patient was referred to our department with the chief complaint of a radio-opaque mass in the maxilla. A biopsy was attempted at a local dental hospital before visiting our hospital, but it was not completed due to severe intraoperative bleeding. The patient presented swelling and induration in the right maxillary region without pain, local heat, or fluctuation. According to radiographic and clinical examinations, intraosseous vascular malformation or a bone-forming tumor such as aggressive osteoblastoma was suspected. Therefore, an open biopsy of the lesion was performed under general anesthesia. Histopathological examination revealed that the lesion consisted of bony trabeculae with fibrous connective tissue and numerous vascular structures, and the lesion was diagnosed as intraosseous vascular malformation.

Abstract
Ⅰ. INTRODUCTION
Ⅱ. CASE REPORT
Ⅲ. DISCUSSION
Ⅳ. CONCLUSION
CONFLICT of INTEREST
REFERENCES

• 윤석민(서울대학교 치의학대학원 구강악안면외과학교실,국립암센터 구강종양클리닉) | Suk Min Youn (Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Research Institute, Seoul National University,Division of oral oncology, National cancer center)
• 한정준(서울대학교 치의학대학원 구강악안면외과학교실) | Jeong Joon Han (Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Republic of Korea) Corresponding author
• 명훈(서울대학교 치의학대학원 구강악안면외과학교실) | Hoon Myoung (Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Republic of Korea)