Malignant Transformation of Ossifying Fibroma into Parosteal Osteosarcoma with High-grade Component: Presentation of an Unusual Case and Review of the Literature

Parosteal Osteosarcoma of the Jaw (POSJ) is a rare entity that is associated with a high survival rate. Several case reports and case series of POSJ have been published in the literature, but few authors have described development of this tumor by possible transformation from a fibro-osseous neoplasm.

We present a rare occurrence of parosteal osteosarcoma with involvement of the posterior maxilla, orbit floor, and infra-temporal fossa in a 20-year-old man. Furthermore, we performed a literature review regarding clinical, radiological, and histological features; treatment strategies; and etiology/pathophysiology.

A PubMed search yielded a total of 74 articles and the articles were sorted according to their corresponding key area of focus.

This was a case of POSJ with high-grade component in the maxillofacial region of a 20-year old male. Co-expression of MDM2 and CDK4 was confirmed. At 2.5-year follow-up, the patient had died. The literature review revealed 18 articles including 20 cases of POSJ. Four cases represent the possible development of this tumor by transformation from a fibro-osseous neoplasm: Two cases of fibrous dysplasia, one case of cemento-ossifying fibroma, and the case of Ossifying Fibroma (OF) in the present study.

In conclusion, we found an unusual case of POSJ of the midface in a patient with a previous diagnosis of OF in the same region. To our knowledge, there have been no previous reports of development of POSJ in OF. Furthermore, this is the first described case of high-grade surface osteosarcoma in the craniofacial region.