Osteolysen

Osteolysis, or osteolyses in plural, is the pathological loss or resorption of bone tissue, resulting in radiolucent areas on imaging. It can affect any bone and may be localized to a site or occur more diffusely. The process is driven by increased activity of osteoclasts, often in response to inflammatory, infectious, neoplastic, or mechanical stimuli, and it can progress if the underlying cause is not addressed.

The pathophysiology commonly involves the formation of osteoclast-activating signals, including cytokines and the RANK/RANKL pathway, which promote bone resorption. In some contexts, wear debris from joint implants or radiation exposure amplifies local osteolysis by triggering inflammatory cells and cytokines. Primary or idiopathic forms are rare and include diseases such as Gorham-Stout disease, which is characterized by progressive, often extensive osteolysis accompanied by proliferative vascular tissue.

Causes of osteolysis are diverse. Localized osteolysis may follow trauma, infection (osteomyelitis), or implant-related wear and loosening. Malignant processes, including lytic metastases and multiple myeloma, can produce focal bone destruction. Systemic conditions such as inflammatory arthritides, osteopenia, or osteoporosis can contribute to generalized bone loss, while radiation therapy can cause radiation-induced osteolysis.

Diagnosis relies on imaging and clinical evaluation. Plain radiographs reveal lytic lesions; CT and MRI define extent and soft-tissue involvement, while bone scintigraphy and PET-CT assess activity and spread. Biopsy may be necessary to determine etiology when the cause remains uncertain.

Treatment targets the underlying cause and may include antiresorptive therapies (such as bisphosphonates or denosumab), infection control, oncologic management, or surgical intervention to stabilize or resect affected areas. Prognosis varies with etiology and the extent of bone loss.