Presentation
Back and leg pain.
Patient Data
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Expansile bone lesion centered on the left T5 pedicle and lamina. It has a narrow zone of transition, and a mixed sclerotic/lytic internal matrix. No definite cortical breach. T5 vertebral body appears sclerotic. The mass significantly narrows the central canal, and the spinal cord is compressed.
Histopathology
MACROSCOPIC DESCRIPTION: "Spinal lesion": An aggregate of hard brown and white bony fragments 50 x 40 x 20 mm.
MICROSCOPIC DESCRIPTION: Sections show an irregularly shaped but circumscribed lesion with surrounding normal lamellar bone. The lesion consists of irregular, haphazardly arranged, evenly spaced spicules of osteoid lined by plump but uniform mononuclear osteoblasts and some osteoclasts. Mitoses are not identified. The space between the osteoid is filled with loose connective tissue with prominent blood vessels. There is a little cartilage attached to normal bone, but there is not cartilaginous differentiation within the lesion. Margins cannot be assessed. There is no evidence of malignancy.
DIAGNOSIS: Spinal lesion: Osteoblastoma.
Case Discussion
Osteoblastomas are rare, benign bone tumors that have a predilection for the posterior elements of the spine.