A 21-year-old woman presents with intermittent pain in her right thigh for six weeks. The pain is present throughout the day, does not disappear at night, is not aggravated by movement or changes in posture, and is not alleviated by paracetamol or NSAIDs. There is no history of urinary or bowel symptoms. Her medical, surgical, and gynecological histories are unremarkable. She does not smoke, but drinks around 4 to 6 units of alcohol per week, and consumes marijuana occasionally. She denies using hard drugs.
Anteroposterior and lateral x-rays of the right femur reveal a permeative lytic lesion within the diaphysis, a soft-tissue mass extending outward from the same region, and a Codman triangle at the bony margin. X-rays of the lumbosacral spine and pelvis are normal.
MRI reveals an irregular 5.8 x 4 cm mass within and extending outward from the right femoral diaphysis. The mass is hypointense on T1-weighted images and heterogeneously hyperintense in T2-weighted images.
Multiple samples of the right femoral tumor are obtained via an open biopsy. Histology reveals multiple sheets of cells with a small, round, blue cell neoplasm, suggestive of a primitive neuroectodermal tumor. Fluorescence in situ hybridization (FISH) reveals positivity for the ES translocation (22q12).
Computed tomography (CT) of the thorax shows no evidence of pulmonary metastasis. Whole body fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) shows no evidence of bony metastasis.