OSTEOSARCOMA IN PAGET DISEASE OF BONE

Abstract

Background Paget disease of bone (PDB) is a disorder of bone metabolism that involves osteoclasts. Osteosarcoma arising in Paget disease is a rare complication of PDB occurring in less than 1% of all osteosarcomas. The aim of this case report is to describe different imaging features of osteosarcomas arising in PDB and its progression. Clinical and Radiographic Findings A 72-year-old female with known arthritis and PDB presented to the emergency room with a 1-week headache and right temporal/parietal skull swelling. The erythrocyte sedimentation rate (ESR) and serum alkaline phosphatase (ALK) were elevated. Planar radiographs of the skull exhibited mixed sclerotic and radiolucent lesions throughout, giving a cottonwool appearance. Multidetector computed tomography (MDCT) of the head showed peripheral enhancement, a partially calcified right temporal region mass, and expansion of the underlying calvarium with a periosteal reaction. Intracranial extension was clear on magnetic resonance imaging (MRI). Furthermore, positron emission tomography/computed tomography (PET/CT) revealed increased fluorodeoxyglucose (FDG) avidity in the solitary right temporal/parietal lesion. Biopsy revealed osteosarcoma with chondroblastic features arising in PDB. The patient underwent right craniectomy and resection of the tumor. Six weeks later, gross recurrent disease at the resection site was found on a head MDCT that demonstrated soft tissue density underlying the cranioplasty with a significant amount of vasogenic edema involving the temporal/frontal lobe. The patient underwent right decompressive and epidural tumor resection. A day later, she was pronounced brain dead. Discussion/Conclusions PDB is often diagnosed through incidental findings in a regular blood chemistry panel, particularly ALK, or through imaging done for another reason. The planar radiograph gives the best clue to the presence of PDB. The MDCT is mandatory for better outcomes in treatment of osteosarcoma, whereas MRI is best for depicting local intracranial extension. PET identifies the region of a tumor through FDG increase. Lastly, biopsy is necessary for confirming the tumor. Paget disease of bone (PDB) is a disorder of bone metabolism that involves osteoclasts. Osteosarcoma arising in Paget disease is a rare complication of PDB occurring in less than 1% of all osteosarcomas. The aim of this case report is to describe different imaging features of osteosarcomas arising in PDB and its progression. A 72-year-old female with known arthritis and PDB presented to the emergency room with a 1-week headache and right temporal/parietal skull swelling. The erythrocyte sedimentation rate (ESR) and serum alkaline phosphatase (ALK) were elevated. Planar radiographs of the skull exhibited mixed sclerotic and radiolucent lesions throughout, giving a cottonwool appearance. Multidetector computed tomography (MDCT) of the head showed peripheral enhancement, a partially calcified right temporal region mass, and expansion of the underlying calvarium with a periosteal reaction. Intracranial extension was clear on magnetic resonance imaging (MRI). Furthermore, positron emission tomography/computed tomography (PET/CT) revealed increased fluorodeoxyglucose (FDG) avidity in the solitary right temporal/parietal lesion. Biopsy revealed osteosarcoma with chondroblastic features arising in PDB. The patient underwent right craniectomy and resection of the tumor. Six weeks later, gross recurrent disease at the resection site was found on a head MDCT that demonstrated soft tissue density underlying the cranioplasty with a significant amount of vasogenic edema involving the temporal/frontal lobe. The patient underwent right decompressive and epidural tumor resection. A day later, she was pronounced brain dead. PDB is often diagnosed through incidental findings in a regular blood chemistry panel, particularly ALK, or through imaging done for another reason. The planar radiograph gives the best clue to the presence of PDB. The MDCT is mandatory for better outcomes in treatment of osteosarcoma, whereas MRI is best for depicting local intracranial extension. PET identifies the region of a tumor through FDG increase. Lastly, biopsy is necessary for confirming the tumor.