PMC4898074_01
53-year-old woman with bone tumor arising in Paget disease. AP radiograph of the pelvis shows Paget disease and bilateral total hip arthroplasty. On the left (arrows) there is destruction of the posteromedial wall of the acetabulum. Additional findings include spinal decompression with laminectomy at L4 and L5 and diffusely enlarged pagetoid bone with cortical and trabecular coarsening.
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A radiograph of the pelvis (Fig. 1) demonstrates bilateral hip arthroplasty components; the device on the left is constrained by a single acetabular screw.
53-year-old woman with bone tumor arising in Paget disease. Axial CT (A) through the level of the pelvic tumor (arrows) a large soft tissue mass adjacent to the medial wall of the acetabulum and obturator foramen is displacing the adjacent, contrast-filled bowel. Coarsened trabeculae, characteristic of pagetoid bone, is evident in the left acetabulum with lucency about the retaining screw of the left total hip arthroplasty. (B) At a lower level, the mass (arrows) has central low density. There is bony destruction of the medial wall of the acetabulum. (C) Coronal CT demonstrates a large soft tissue mass (arrows) with destruction of the medial wall of the left acetabulum. At T12, a lucent lesion is present in the vertebral body (arrowhead). Beam hardening artifact related to the dense metallic components of bilateral total hip arthroplasty implants is noted in the pelvis in all images.
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A CT scan (Fig. 2) demonstrated a large intrapelvic mass, adjacent to and eroding the medial acetabular wall and quadrilateral plate of the left hemipelvis.
53-year-old woman with bone tumor arising in Paget disease. (A) Sagittal CT (B) enlargement of sagittal to better demonstrated detail, and (C) axial images through T12. There is a large lucent lesion in the T12 vertebral body with destruction of the posterior cortex of the vertebral body and slight protrusion into the spinal canal (arrows). At the level below the lesion, cortical and trabecular coarsening at L1 form a classic "picture frame" vertebral body pathognomonic of Paget disease (arrow head). Compression fractures are evident at L2 and L4. Diffuse idiopathic skeletal hyperostosis (DISH) is present from T8-11.
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Sagittal reformations of this study (Fig. 3) reveal a large lucent lesion in the T12 vertebral body with destruction of the posterior cortex of the vertebral body and slight protrusion into the spinal canal.
53-year-old woman with bone tumor arising in Paget disease. F-18 FDG PET images, (A) frontal, (B) oblique (C) posterior, reveal a markedly hypermetabolic appearance of a portion of the calvarium, the right humerus, and both femurs which are also curved; findings which can be seen in Paget disease. Although there is uptake in the bilateral pedicles at T12, there is no significant uptake in the spinal lesion at T12 (arrow). Only mild uptake is seen in the posterior acetabulum in the region of the erosive lesion (arrow). No significant uptake is seen in the pelvic mass (arrows). The Axial image (D) obtained through the pelvis at the level of the mass confirms absence of activity at the medial wall of the left acetabulum as well as throughout the region of the mass (arrows). Urinary artifact is present below the pubic symphysis in images A, B, and C.
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A PET scan (Fig. 4) was performed to further investigate the mass.
53-year-old woman with bone tumor arising in Paget disease. Cellular primitive fibroblastic spindle cell proliferation with primitive cytological atypia, mitotic activity, and intercellular bone formation (center left and center right).
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The histological characteristics of the tumor were further investigated with an open biopsy, which showed a cellular fibroblastic spindle cell neoplasm with cytological atypia, necrosis, and mitotic activity (Fig. 5A) as well as regions of malignant bone and cartilage formation (Fig. 5B) and giant cell rich areas. Although we cannot entirely exclude this possibility, the giant cell rich areas contained similar spindle cells as the remainder of the tumor (Fig. 5C), and therefore, the pelvic mass was interpreted as a high grade osteosarcoma with giant cell features rather than as colliding lesions.