Malignant bone disease (osteosarcoma)

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Malignant bone disease (osteosarcoma)

To understand the mechanisms of occurrence of a particular disease of bone tissue and bones in general (tumors, osteosarcomas), one should carefully study what bone and bone tissue are in themselves.

Bone is a specialized connective tissue that, like all connective tissues, contains cells and the extracellular matrix. The extracellular matrix is composed of organic and inorganic material.

When the bones are damaged by a tumor, local bone resorption by osteoclasts occurs, which can lead to pathological bone fractures of the vertebral bodies. MRI of the cervical spine shows a compression fracture of the vertebral body, complicated by compression of the spinal cord (indicated by arrows).

With extensive damage to the bones by a tumor, most often with metastases of breast cancer, myeloma, and lymphoma, osteolytic hypercalcemia occurs, in which the waste products of tumor cells, for example, cytokines, stimulate local bone resorption by osteoclasts. Multiple myeloma may be the most common cause of pathological fracture requiring urgent surgery in some practice settings.

CT scans revealed pathological fracture involving the T3 vertebral body with significant retropulsion, shown in the sagittal plane (A), as well as the destruction of the posterior bony elements. Sagittal T2-weighted MRI demonstrates severe cord compression with increased cord signal adjacent to the fracture (B).
Epidural disease is noted on T1-weighted imaging with contrast in the sagittal (C) and axial (D) planes, extending from T1 to T4, producing compression of the thecal sac and spinal cord.

In solid tumors (osteosarcomas), bone resorption is stimulated by the tumor secreting peptides like a parathyroid hormone. Humoral paraneoplastic hypercalcemia occurs: tumor metabolites have a general effect, reducing calcium excretion.

PTH-like peptides have sections of the amino acid sequence similar to PTH, they act through the receptors for this hormone and are not detected by immunoassay. Growth factors, prostaglandins, and especially cytokines that activate osteoclasts, which are often elevated in leukemia, affect stimulating bone resorption.