Age / Sex : 31 / F

Chief complaint: lower back pain for 6 months

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy: Sun Joo Lee, Inje University Busan Paik Hospital

Discussion

Answer: Giant cell tumor

Findings:

Axial CT image (a) shows osteolytic and expansile mass in S2 and S3 vertebral bodies with cortical thinning or a thin sclerotic margin. Axial T1-weighted MR image (b) shows heterogeneous intermediate SI lesion in S2 and S3 vertebral bodies with extension into sacral canal. Sagittal T2-weighted MR image (c) shows heterogeneous low SI with some internal intermediate SI portion. Sagittal Gd-enhanced T1-weighted MR image (d) shows intense heterogeneous enhancement.

Differential Diagnosis: chordoma, eosinophilic granuloma, plasmacytoma, metastasis

Diagnosis: Giant cell tumor

Discussion:

Giant cell tumor is second most common primary sacral tumor after chordoma. Compared with chordomas, which are central lesions, sacral giant cell tumors are frequently eccentric and abut or extend across the sacroiliac joint. Tumors in women predominate (2:1). Patients are usually affected between the ages of 15 and 40 years. Pain and neurologic deficits are the most common presenting symptoms. A giant cell tumor is composed of osteoclastic giant cells within a spindle cell stroma. Hemorrhagic and fibrotic areas are commonly found. Spontaneous malignant transformation was reported in fewer than 2% of patients, but it often occurs after radiation therapy. Giant cell tumors are purely lytic destructive lesions. Matrix calcifications and septations are absent. On CT scans and MR images, giant cell tumors are frequently heterogeneous because of the presence of necrosis (low-attenuation areas), hemorrhage (high-signal-intensity areas on T1- and T2-weighted sequences or fluid–fluid levels), or cystic spaces. Low signal intensity is frequently noted on T2-weighted images and is related to the high hemorrhagic and fibrotic content of this tumor. It is very vascular neoplasm. Therefore, it shows significant enhancement on Gd-enhanced T1-weighted image.

References:

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