Spontaneous malignant transformation in craniomaxillofacial fibrous dysplasia

Spontaneous malignant transformation in craniomaxillofacial fibrous dysplasia (FD) is extremely rare and its clinicopathological characteristics remain largely unknown. Here, we aimed to characterize the epidemiology and clinicopathological features of malignancies arising from preexisting FD by presenting data from a Chinese tertiary referral hospital and review of English and Chinese literatures. The craniomaxillofacial disease registry of Shanghai Ninth People's Hospital was searched and reviewed to collect relevant information for patients diagnosed as malignant transformation in craniomaxillofacial FD between January 1993 and December 2010. An English and Chinese literature review was conducted to retrieve pertinent cases published in the past 2 decades with preset inclusion criteria. All included cases were further analyzed with regard to associated clinical and pathological variables. Three cases with osteosarcoma arising from previous craniomaxillofacial FD were found at our institution and 35 other cases were identified by literature review. These uncommon entities usually occurred in adults with a mean age of 39.8 years and equal gender preponderance. Maxilla remained the most common sites for malignancies followed by mandible and zygoma. Most malignancies were diagnosed as osteosarcoma followed by fibrosarcoma, chondrosarcoma, and malignant fibrous histiocytoma. Radical resection alone or with postoperative radiotherapy/chemotherapy remains the main treatment strategy with unfavorable prognosis due to local recurrence and distant metastasis. Taken together, our findings might for the first time provide the comprehensive information regarding the epidemiology, clinicopathological features, treatment, and prognosis of malignancies in craniomaxillofacial FD. Further investigations are warranted to improve early diagnosis and proper treatment for these uncommon entities.