Osteolytic Lesions in Myeloma

Causes of Progressive Bone Deterioration in Cancer

Osteolytic lesion of tumor of the lower end of the radius. Sarindam7/Wikimnedia Commons/CC by 3.0

Osteolytic lesions (also known as osteoclastic lesions) are areas of bone damage where the bone has softened due to malignancies such as myeloma and breast cancer. The lesions themselves appear as tiny holes on an X-ray. People commonly refer to them as having a "moth-eaten" or "punched-out" appearance.

The development of osteolytic lesions can lead to pain, spinal cord compression, and an increased risk of bone fracture. Treatment typically involves the use of medications to prevent further bone loss and radiation therapy to relieve pain and other associated symptoms.

Causes of Osteolytic Lesions

Osteolytic lesions form when there is an imbalance in a biological process called bone remodeling. This is where old cells on the skeleton are broken down and replaced by new ones. During certain types of cancer, such as myeloma, this process can be thrown off balance with the production of new cells unable to keep up with the loss of old ones.

In regards to myeloma specifically, there are several reasons why this happens. There is one type of cell called an osteoblast which is responsible for building bone; the other is an osteoclast which releases substances that break down bone as a part of the remodeling process. When myeloma invades bone tissue, it inhibits the osteoblasts while stimulating osteoclasts to break down cells even faster. What results are pockets of deterioration where the cell structure is often similar to that of a loofah.

In addition to myelomas, the most common cause of osteolytic lesions is metastatic cancers (cancers that had spread beyond the site of the original tumor). These include metastatic cancers of the prostate, thyroid, lungs, kidney, and breast. Lesions are most often found in larger bones, such as the skull, spine, pelvis, ribcage, and larger bones of the legs.

Consequences of Bone Damage in Myeloma

Osteolytic bone lesions can cause a range of symptoms irrespective of cancer itself. Among them:

  • Bone pain is common and can be very severe, often accompanied by nerve damage and pain caused by bone compression
  • Osteoporosis (the progressive weakening of bone)
  • Pathological fractures caused by bones which have been weakened by cancer
  • Hypercalcemia of malignancy in which bones are broken down by cancer release excessive calcium into the bloodstream. The can lead to nausea, vomiting, weakness, confusion, myalgia (muscle pain) and arthralgia (joint pain). Arrhythmia (an irregular heart rate) is also a common problem that, if left untreated, can be fatal.

Treating Osteolytic Lesions

Osteolytic lesions are treated with a combination of low-dose radiation and bisphosphonates, a class of drug commonly used in people with osteoporosis. Reclast (zoledronic acid) is another medication specifically used in cancer to prevent the worsening of bone lesions.

Bisphosphonates are given intravenously approximately every four weeks. Side effects include reduced kidney function and, in rare cases, osteonecrosis of the jaw (where the bone of the jaw begins to deteriorate).

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    Article Sources
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    • Reagan, M.; Liaw, L.; Rosen, C.; et al "Dynamic interplay between bone and multiple myeloma: emerging roles of the osteoblast." Bone. 2015; 75:161-9.