Sarcomatous Transformation of Osteochondroma of the Coronoid Process Forming Pseudoarthrosis With Zygomatic Arch Mistaken for Jacob Disease

Abstract

Osteochondromas are the most common benign osseous neoplasms, with a propensity to involve long bones. The involvement of the coronoid process is extremely rare, and osteochondromas of the coronoid process may form pseudoarticulations with the zygomatic arch when large, an entity that is extremely rare and termed as Jacob disease. Sarcomatous degeneration of osteochondroma of the coronoid process is an extremely rare entity and has not been described to date. Only 1 case of primary mesenchymal chondrosarcoma has been described. We present a case of a 24-year-old man with a chondrosarcoma of the coronoid process, who was wrongly diagnosed with Jacob disease on the basis of radiologic findings.

Mandibular Chondrosarcoma Reconstructed Using Custom Implant and Radial Forearm Free Flap

“…Furthermore, each case is unique in that different locally aggressive and malignant chondrogenic tumor histologic subtypes are described. The first reported case describes a mesenchymal chondrosarcoma and the second reported case describes a secondary chondrosarcoma originating from transformation of an osteochondroma 2,3 . The World Health Organization has classified chondrosarcomas into different subtypes based on histological features: conventional central, periosteal, dedifferentiated, mesenchymal, and clear cell chondrosarcomas 4 .…”

“…The first reported case describes a mesenchymal chondrosarcoma and the second reported case describes a secondary chondrosarcoma originating from transformation of an osteochondroma. 2,3 The World Health Organization has classified chondrosarcomas into different subtypes based on histological features: conventional central, periosteal, dedifferentiated, mesenchymal, and clear cell chondrosarcomas. 4 Conventional central chondrosarcomas, the most common, can be further classified as either primary (arising de novo) or secondary (arising in pre-existing enchondroma or osteochondroma).…”

“…The mandibular coronoid process is rarely involved, with only 2 previously reported cases. 2,3 In 2007, Angiero reported the first case of a mesenchymal chondrosarcoma occurring in a 65-year-old woman in the temporomandibular joint involving the left coronoid process. 2 The second reported case was a 24-year-old man with sarcomatous transformation of an osteochondroma of the coronoid process described by Jha in 2013.…”

“…2 The second reported case was a 24-year-old man with sarcomatous transformation of an osteochondroma of the coronoid process described by Jha in 2013. 3 Surgical resection of chondrosarcomas is the standard for management. 1 However, due to limited tumor incidence at the coronoid process, and variability in local tissue involvement, location, and grade, surgical approaches and reconstructive methods of involved structures have not been well established and remain subject to individual surgeons' discretion.…”

“…These head and neck chondrosarcomas most commonly originate in bones and joints of the skull base, with only 4.5% of these tumors originating in the mandible. The mandibular coronoid process is rarely involved, with only 2 previously reported cases 2,3 . In 2007, Angiero reported the first case of a mesenchymal chondrosarcoma occurring in a 65-year-old woman in the temporomandibular joint involving the left coronoid process 2 .…”