What is Lytic Bone Lesions?
Bone tumors are, for the most part, not cancerous. The major factors that can help assess bone tumors through images are their appearance on simple x-rays (like well-defined holes, irregular holes, or dense spots) and the age of the patient when the tumor is found. Bone injuries that are well-defined and are eating away the bone can mean different things based on the patient’s age. To keep these possibilities in mind, there’s a helpful acronym, FEGNOMASHIC. We will try to showcase the most notable features of each type of these tumors.
The different bone tumors and lesions we’ll talk about include fibrous dysplasia, eosinophilic granuloma, enchondroma, giant cell tumor, non-ossifying fibroma, osteoblastoma, aneurysmal bone cyst, solitary bone cyst, hyperparathyroidism (also known as Brown tumor), and infections. Other possibilities include chondroblastoma, CMF, metastasis, and myeloma. Particularly in patients 40 years and older, any bone injury should be checked for metastasis and myeloma.
There’s a condition that can look like bone eating lesions called pseudocysts. These are areas of bone where there’s less cross-linking of the natural bone structure and often occur in areas of the body where there isn’t a lot of stress, like the larger bump on the top of the upper arm bone, the heel bone, and the radial tuberosity. If there’s a bone-eating injury with unclear edges, it’s usually a sign of harmful bone tumors (like Ewing sarcoma, osteosarcoma, metastasis, leukemia) and aggressive non-cancerous injuries (like giant cell tumor, infection, eosinophilic granuloma).
What Causes Lytic Bone Lesions?
The causes of bone tumors can vary widely. They can be present at birth, develop as you grow, occur due to metabolic disorders, happen because of other bone tumors, or be a result of cancer spreading from another part of the body. For instance, a type of bone change called fibrous dysplasia happens due to a random mutation of a protein that’s supposed to control cell growth. This mutation leads to the unnatural overproduction of a chemical messenger in the body called cyclic-adenosine monophosphate (c-AMP).
This overproduction results in normal bone formation being replaced with a network of fibrous (thread-like) tissue and patches of immature, woven bone.
Risk Factors and Frequency for Lytic Bone Lesions
Benign tumors and similar lesions make up about 79.3% of all musculoskeletal abnormalities, and are slightly more likely in females. On the other hand, malignant tumors represent only 20.7% of these lesions, and are slightly more common in males. The three most frequently seen benign bone lesions are osteochondroma, enchondroma, and simple bone cysts. In the younger population, benign bone tumors are more commonly found than malignant ones. However, after the age of 40, malignant bone tumors, primarily metastases and myeloma, are more frequently observed.
- About 79.3% of all musculoskeletal abnormalities are benign tumors or similar lesions and are slightly more common in females.
- Malignant tumors make up only 20.7% of these anomalies and are slightly more prevalent in males.
- The most common benign bone lesions are osteochondroma, enchondroma, and simple bone cysts.
- Benign bone tumors are seen more often in the younger population.
- Malignant bone tumors, such as metastases and myeloma, become more common after the age of 40.
Signs and Symptoms of Lytic Bone Lesions
The first steps in examining a possible bone tumor involve checking the patient’s medical history and doing a physical examination. Symptoms could include pain, a noticeable lump, or some unusual results from an X-ray taken for another reason. Most benign, or non-cancerous, bone lesions don’t cause symptoms and are only found by accident during imaging for other issues. However, they can sometimes cause pain resulting from activity or inflammation of the surrounding bone tissues.
Several benign conditions that don’t cause inflammation or pain include fibrous dysplasia, enchondroma, non-ossifying fibroma, and solitary bone cyst. For malignant, or cancerous, bone tumors such as primary or metastases, the pain is often constant and not linked to activity, due to the impact on nerves and blood vessels. Tumors in soft tissue usually show up as a lump, except for those in the nerve sheath, which cause pain.
Though some bone tumors are more common in one gender over the other, it doesn’t typically influence diagnosis or treatment. Sometimes, family history can be helpful for conditions like multiple enchondromas and bone dysplasia in neurofibromatosis, which are passed down genetically. Age is also a significant factor as different types of benign and malignant bone tumors occur in specific age groups. Some people can have multiple bone lesions from conditions like fibrous dysplasia, eosinophilic granuloma, enchondroma, metastasis, and myeloma, hyperparathyroidism, hemangiomas, and infection.
One example of a syndrome that can cause bone lesions is McCune-Albright syndrome and Mazabraud syndrome. The physical examination should take into account the patient’s general health and any abnormalities beyond the area of interest, like cafe-au-lait spots (light brown spots on the skin).
A specific examination of the affected area would focus on visual inspection, feeling for abnormalities, changes with movement, examination of nearby structures, and any other relevant checks.
Testing for Lytic Bone Lesions
When doctors suspect a bone tumor, they use several imaging techniques to help determine what the issue may be. One of the first steps involves taking X-rays or a radiograph of the bone. Depending on the location of the bone issue and the patient’s age, the X-ray can often provide enough information to make a diagnosis. For example, a finding in the area of a bone near a joint (known as the epiphyseal region) in a bone that has stopped growing (fused physis) might indicate a certain type of tumor called a giant cell tumor. Different types of lesions, like fibrous dysplasia or osteoblastoma, could be found if the long narrow part of the bone (diaphyseal) is affected.
Aggressiveness and whether the bone issue is benign (non-cancerous) or malignant (cancerous) can often be determined from X-rays. Generally, less aggressive issues have clear boundaries with a surrounding hardened (sclerotic) rim, whereas more aggressive ones have fuzzy borders. Other patterns doctors look out for include changes in the structure of the bone, reaction of the bone tissue to the tumor, and any indicators of new bone growth.
For bone issues affecting soft tissue, X-rays may not be as helpful, but they can still provide some valuable information like conglomerates of tiny calcium deposits in blood vessels (phleboliths) that are associated with a type of benign tumor called hemangioma.
Computed tomography (CT) scan is another imaging technique doctors usually use to get a clearer picture of the bone issue. CT scans help to assess calcified areas, new bone formation, and the condition of the bone surface. For malignant tumors, CT scans also help to determine how widely the cancer has spread, its impact on surrounding tissues, and how invasive the surgery might need to be. MRI scans, on the other hand, provide better images of soft tissues and can help differentiate certain types of bone cysts. In cases of malignant tumors, MRI scans can estimate the extent of involvement in the bone marrow.
Other scans like Technetium Bone Scans and Positron Emission Tomography (PET) scans are helpful in identifying active bone issues and determining whether cancer has spread. However, these scans can sometimes give false results. Ultrasounds help in differentiating between solid and liquid-filled (cystic) bone issues and provide better images of soft tissue issues.
In addition to imaging, doctors may also order blood and urine tests to rule out infections or other diseases like leukemia. The results may also help predict how well the wound might heal after surgery. Biopsies are usually the last step and test to finalize the diagnosis, and they require careful planning.
Certain types of bone issues worth mentioning, include Fibrous Dysplasia, which replaces bone with disorganized fibrous tissue; Eosinophilic Granuloma, a rare disease that causes inflamed areas in the bone; Enchondroma, the most common benign issue of fingers; Chondroblastomas, tumors that usually occur in areas near the joints; and Metastasis, which are cancer cells that have spread from another part of the body to the bone.
Understanding what type of bone issue a patient has helps doctors plan the most effective treatment strategy.
Treatment Options for Lytic Bone Lesions
Bone lesions, or abnormal changes in bone tissue, are often diagnosed based on their symptoms, X-ray appearances, and results from biopsies, where a small sample of tissue is taken and examined under a microscope. To plan treatment and predict outcomes, doctors use a staging system, or a way of categorizing the condition based on its characteristics.
In the case of benign bone tumors, or non-cancerous bone growths, the following stages apply:
Stage 1 represents dormant tumors. These do not cause symptoms and are usually detected by chance during imaging examination for unrelated reasons. They are known for their well-defined appearance on radiographs, and they do not destroy or expand the bone, which means there’s no need for treatment. An example of a Stage 1 tumor would be a small, symptom-free non-ossifying fibroma, a benign growth often found in the knees of children and young adults.
Stage 2 includes active tumors. These tumors are growing and can cause symptoms such as pain or bone fractures. They are well-defined but may expand and thin the outer layer of bone. These lesions are usually treated with extended curettage, a procedure where the tumor is removed.
Stage 3 includes aggressive tumors. These growths break through natural barriers and typically break through the outer layer of the bone. Their treatment can involve extended curettage, marginal resection (surgical removal of the outer layer of the tumor and some healthy tissue), or wide resection (removal of all of the tumor and more surrounding healthy tissue) if necessary.
Muscoskeletal sarcomas, a type of malignant or cancerous tumor that arises in the muscles, bones, or soft tissues, are also staged but based on their grade (how much the cancer cells resemble normal cells when viewed under a microscope), size, and whether or not they have spread to other parts of the body.
Bone lesion treatment requires experienced surgeons and often depends on a range of factors, including whether surgery or non-surgical treatment is appropriate, the choice of medication, the location of the tumor, whether the skeleton is still growing, and the specific type of bone tumor. For instance, aneurysmal bone cysts (ABCs), or benign bone lesions filled with fluid, are often managed by removing the cyst and filling the void with a bone graft. Some lesions are also associated with infections, and these may require treatment with antibiotics and possible surgical removal of the affected tissues.
For cancers that start in the bone, the primary goal of treatment is to remove or eliminate the cancer. In cases where the cancer has spread to the bone from other parts of the body, the primary goal is to manage pain. Treatment often involves a combination of radiation therapy, medication, and surgery.
However, there are benign bone lesions that do not require treatment. For example, non-ossifying fibroma, a common benign bone tumor, and unicameral bone cyst of the calcaneus, a fluid-filled sac inside the bone of the heel, are typically asymptomatic and rarely cause fractures. When these lesions are identified on an X-ray, no biopsy or treatment is usually necessary.
What else can Lytic Bone Lesions be?
Different types of bone lesions can occur in various parts of the bones and at different ages. Here are some examples:
Epiphyseal Lesions (occur in the ends of the bones)
- Chondroblastoma: usually found in individuals aged 10 to 25 years
- Giant cell tumor: typically develops in people aged 20 to 40 years
- Chondrosarcoma: this is a rare condition
Diaphyseal Lesions (located in the main shaft of a long bone)
- Ewing sarcoma: common among ages 5 to 25 years
- Lymphoma: a type of cancer that starts in body’s immune system
- Fibrous dysplasia: generally seen in patients between 5 to 30 years old
- Adamantinoma: this specific condition frequently affects tibia (a bone in the leg)
- Histiocytosis: mostly found in people aged 5 to 30 years
Multiple Lesions (where more than one part of the bone is affected)
- Histiocytosis: a type of lesion caused by an excess of white blood cells called histiocytes
- Enchondroma: benign (non-cancerous) cartilage tumor
- Osteochondroma: benign bone growth that usually develops during childhood or adolescence
- Fibrous dysplasia: a bone disorder characterized by abnormal fibrous tissue growth
- Metastasis: cancer cells that have spread from the place where they first started
- Multiple myelomas: cancer of plasma cells that induces multiple tumors within bone
- Infection: microorganisms such as bacteria or viruses causing damage
- Hyperparathyroidism: excess production of parathyroid hormone causing bone loss
- Hemangioma: a benign tumor made up of blood vessels
Possible Complications When Diagnosed with Lytic Bone Lesions
Benign bone tumors can cause a variety of complications, both from the tumor itself and the treatment. These complications may include pain, the formation of an unusual bone cyst, a fracture caused by weakening of the bone due to the tumor, or even the benign tumor turning into a malignant or cancerous one.
Treatments also can lead to complications, such as the tumor coming back, mobility problems, or other side effects.
Malignant or cancerous bone tumors can bring about complications like pain, fractures, loss of function, and a reduced quality of life due to the side effects of treatment. In the most severe cases, these lesions can even result in death.
The process of managing bone and muscle lesions involves dealing with all these potential issues.
Common Complications:
- Pain
- Formation of an unusual bone cyst
- Fracture due to weakening of bone
- Benign tumor turning malignant
- Tumor recurring after treatment
- Mobility problems
- Treatment side effects
- Loss of function due to malignant bone tumor
- Reduced quality of life due to treatment side effects
- Potential death in extreme cases
Preventing Lytic Bone Lesions
It is important for patients to be informed about their illness and the various treatment options available to them. Conditions affecting the bones and muscles can vastly differ from one another, each requiring a unique approach to treatment. For instance, if a patient has a non-cancerous bone condition that shows no symptoms and isn’t progressing, it’s usually left untreated.
However, when the condition becomes active and painful, or it leads to pathological fractures (broken bones caused by a disease), it needs active treatment. More serious bone cancer might necessitate extensive cleaning out (curettage) or wide removal (resection). For bone lesions that have spread from other parts of the body (metastatic), the main aim is usually to manage pain and offer comfort care (palliative care).
Meanwhile, primary malignant bone tumors (cancer that starts in the bone) are treated aggressively whenever possible. It is crucial to realize that the management of these bone and muscle conditions depends on various factors and being educated about their condition helps patients achieve better treatment outcomes.