Findings: Figures 1-3
MRI images through the base of the skull demonstrate a well-defined enhancing mass (3.5 x 4 cm) involving the left mandible including the angle and condyle. There is underlying abnormal marrow signal within the mandible. The mass is adjacent to the inferior aspect of the temporal bone and involves the left zygomatic arch. Cortical involvement of the inferior temporal bone could not be excluded.
Figures 4-6
CT scan images through the face demonstrate the soft tissue mass based on the neck of the mandible and surrounding it laterally, medially and anteriorly. There is "hair on end" periosteal reaction with cortical destruction of the bone. There is bony involvement of the left zygomatic arch. There is questionable involvement along the posterior aspect of the maxillary sinus.
Figures 7-8
PET scan images of the neck demonstrate a large focus of intensely increased radiopharmaceutical uptake in the left infratemporal fossa. At its inferior aspect, it has a central photopenic defect implying necrosis. The margins of the mass abut portions of the skull base. There was concern about tumor involvement of the temporal bone which appears normal by PET. The activity abuts the lateral aspect of the left maxillary sinus. Involvement of this bone cannot be excluded.
Diagnosis: Ewing’s Sarcoma.
Discussion: Ewing’s sarcoma represents approximately 4-10% of all bone tumors. It is the most common malignant bone tumor in children with the peak age being 15 years old. Males are affected twice as much as females and the overwhelming majority of patients are Caucasian (96%).
The most common clinical signs and symptoms include severe localized pain, soft tissue mass, fever, leukocytosis, weight loss, and anemia. Commonly affected regions include: femur (25%), pelvis-ilium (14), tibia (11), humerus (10), fibula (8), and ribs (6). When long bones are affected, Ewing’s sarcoma is typically metadiaphyseal in location.
Radiologic features include "Moth-eaten" permeative bony destruction, exuberant periosteal reaction (onion skin, sunburst, spiculated, hair on end), cortical erosion, and presence of an associated soft tissue mass.
Metastatic disease commonly affects the lungs and bones. Pathologic fractures are evident in 2 to 15% of cases. The 5 year survival rate is 60 to 75%.
References:
Dahnert W. Radiology Review Manual, 3rd Edition, Williams & Wilkins, 1996, p.52.
Resnick D. Diagnosis of Bone and Joint Disorders, 2nd Edition, W. B. Saunders Company,
1996, pp 1055-1059.
Submitted by: