Benign Tumors: Bone & Soft Tissue
Orthopaedic Oncology Service
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Explore Benign Bone & Soft Tissue Tumors
Benign Bone Tumors
Benign bone tumors almost never metastasize and are best classified by the matrix which the tumor cells produce such as bone, cartilage, fibrous tissue, fat or blood vessel. Some of these tumors can be described as 'aggressive' because they may recur locally after removal (resection). It is very important to determine whether a tumor is benign or malignant to avoid over or under treatment of the patient.
Types of Benign Bone Tumors
A benign bone tumor that produces bone and is small. The patient presents with a small, painful lesion. Other symptoms include tenderness, swelling and a limp. Pain is sharp, deep, usually worse at night and relieved with aspirin. X-rays have a classic pattern which shows a small round or oval focus called a nidus. These tumors usually occur between the ages of 10-20, rarely over age thirty. They are most commonly located in the tibia and femur, but have occurred in almost every bone. Treatment used to be by excision only. Now, there is a newer, non-invasive procedure called heat ablation which is performed by our radiologists. This procedure involves placing an electrode into the tumor which is heated causing a 'microwave' treatment to the tumor. Patients receive general anesthesia for the procedure, but go home the same day with a bandaid over the probe site. Surgical excision involves a two to four day hospital stay. Incomplete excision or curettages (scraping out) of the lesion may lead to tumor recurrence.
Much less common than the osteoid osteoma. It may be confused with a malignant tumor and may behave very aggressively. These tumors occur at any age and can be found in any bone but are most common in the spine and long bones. Symptoms include tenderness, swelling, limited motion if near a joint, and pain (not as severe as the osteoid osteoma). The lesion can be seen on plain x-rays. Treatment consists of curettage (scraping out) of the lesion with bone grafting or an excision (removal) depending on the site and potential functional problems. 'Aggressive' osteoblastomas need closer monitoring to rule out recurrence.
Definition: Benign primary bone tumor composed of chondrocytes producing cartilage matrix that arises in medullary cavity.
- Frequently affected bones: femur, tibia, humerus, fibula
- Small bones of the hands and feet
- Usually asymptomatic (no symptoms)
- Many times found during work-up of another condition
- Relatively common to be diagnosed in patients with pain associated with other abnormalities (such as osteoarthritis of a joint, torn menisci or rotator cuff tears)
- Plain x-rays of symptomatic areas will show the lesion
- Infrequently painful except when there is a fracture through the tumor
- Painful cartilage lesions (enchondroma) should raise the possibility of a malignant tumor (chondrosarcoma)
- Multiple enchondromas appear in certain syndromes: Ollier Disease (two or more enchondromas); Maffucci Syndrome (two or more enchondromas associated with soft tissue vascular tumors, hemangioma)
- Most asymptomatic enchondromas can be clinically followed with annual x-rays after initial work-up.
- Surgery (curettage & packing with bone graft or cement) may be done given certain clinical patient circumstances.
Multiple Enchondromatosis (Ollier's and Maffucci's syndromes)
Less common than the enchondroma and does occur with increased frequency in families. These lesions are usually found at an early age and range in severity from a mild abnormality to severe deformities of the skeletal system, such as large bony masses on the hand bones or shortening and bowing of the extremities. Treatment is focused on correcting or preventing deformities which includes removing (resecting) these masses or placing metal rods in long bones to stabilize the deformed or fractured bones. These tumors can become malignant but this is not very common. Thus, the patients are carefully observed with follow-up (serial) x-rays throughout their lifetime.
A very rare benign tumor and occurs more frequently in males especially during adolescence. Most common sites are the top (proximal) and bottom (distal) of the femur, proximal humerus and proximal tibia. There are growth plates also located in these areas. If left untreated, growth of the involved bones could be interrupted. On x-ray, the lesion is round to oval in shape. Treatment usually requires curettage and packing of the lesion with autologous or allograft bone with careful attention to avoid injury to the growth plates. These tumors have about a 20% chance of recurring after curettage.
A very rare benign tumor made of fibrous myxoid elements. It may occur at any age, but usually between twenty and thirty. Most common sites are the proximal tibia and distal femur. On x-ray, it looks very unique because it expands the edges (cortex) of the bone into the soft tissues and has a scalloped inner margin. Treatment is either curettage with bone grafting or excision (removal) in suitable locations. These tumors have the highest rate of recurrence (40%) of any benign cartilage lesion. Thus, the patient must be followed closely for several years.
Solitary Osteocartilaginous Exostosis (OCE) or Osteochondroma
The most common benign tumor of bone probably caused by a genetic defect in the cartilage of an embryo (unborn child). They occur at the ends of bones at any age. The patient presents with a hard, painless mass fixed on the bone. On x-ray they appear as bony outgrowths of the cortex (side of the bone) projecting away from the joints. Examination of this tumor's tissue shows a cartilage cap which causes its growth, very similar to the growth of a normal bone. These tumors usually do not cause the patient trouble. However, if pain develops or they fracture or interfere with surrounding vessels and nerves, the tumor is removed (excised). Recurrence is unlikely, as is the possibility of the benign tumor turning malignant.
The multiple hereditary form of osteocartilaginous exostosis (HMOCE) is a genetic autosomal dominant problem in which multiple osteochondromas develop. They may distort the skeleton and cause functional problems. Common characteristics include short stature, bowing or knock-knee deformities of the lower legs, forearm or hand deformity, and poor joint function. Treatment focuses on managing these deformities in childhood and monitoring them in adulthood to see if the benign status changes to a malignant one. In these patients there is a very low chance of one of the osteochondromas becoming malignant in adulthood, but this is not common. Onset of pain or sudden growth in tumor size should cause the patient to seek medical attention for further staging studies. Bone scans are helpful in following these lesions in adulthood. Again, treatment consists of excision if the patient has symptoms. Malignant tumors, usually low grade chondrosarcomas, which arise from the previously quiet benign lesions are also excised. Additional treatment such as radiation or chemotherapy is seldom.
Fibrous Cortical Defect and Non-Ossifying Fibroma (NOF)
The most common benign bone tumors in children. Both types are located in the shafts of the long bones, especially the distal femur, proximal and distal tibia and also in the upper extremities (proximal humerus, distal radius and ulna). Most of these tumors disappear after adolescence. They usually do not cause symptoms unless a fracture has occurred. Biopsies to confirm diagnosis are usually unnecessary because the tumor appearance on x-ray is so classic. The fibrous cortical defect has a thick bony margin and slight bulging of the edge or side (cortex) of the long bone. By adulthood, the lesions move away from the growth plate and heal. The cause of these lesions is unclear, but may be related to a defect in the growth plate. No metastases have ever been reported. These tumors usually disappear (spontaneous regression). Treatment involves observation with routine x-rays if the diagnosis can be made from the original x-ray. If the diagnosis is in doubt, or if the lesion is likely to weaken the bone and cause a fracture through the lesion, then biopsy and curettage with bone grafting is advised. If a pathologic fracture occurs, it is allowed to heal before surgical treatment because sometimes the lesion will disappear during fracture healing. Non-ossifying fibromas are virtually identical, but larger.
A problem of the bone tissue that probably is a developmental abnormality of the bone versus a true tumor. It is not familial or hereditary. Sometimes diagnosis is made during childhood, but it can go unrecognized until adulthood. On x-ray these tumors have a 'ground glass' appearance and can cause thinning of the cortex. The bone may be enlarged and deformed. Some patients sustain fractures through the lesion. With fibrous dysplasia, the normal bone is replaced with masses of fibrous tissue and thin weak bone. A biopsy may be necessary to rule out more aggressive lesions. Treatment involves correction of bony deformities which usually requires curettage and packing of the lesion with possible internal fixation (metal hardware) if the lesion is located near a joint or a body area requiring extra support. this tumor presents a more difficult problem in the proximal femur. These tumors rarely turn malignant.
Unicameral Bone Cysts
Occur primarily in children. The cause is unknown but it is thought to be an abnormality of the growth plate or circulation problems of the veins of the bone involved. The cysts are usually found in the proximal humerus of a growing child but may occur in the proximal femur and other bones. In adults, these lesions may be found in the heel (calcaneus) or flat bones. They are usually discovered incidentally or after a fracture through the cyst. The cyst is clearly outlined on an x-ray. The bone is widened and the cortex is thin. The cavity of the cyst is filled with a serum-like fluid. Treatment is by needle aspiration of the cyst with steroid injection or bone marrow and demineralized bone matrix (Grafton®) injection. This is a day surgery procedure under general anesthesia with a success rate of about 80%, but it may require three or more injections to make the cyst heal. Curettage and packing with bone graft is the more invasive procedure requiring a surgical incision and a few days in the hospital. Malignancy arising from a cyst almost never happens.
Aneurysmal Bone Cyst
A benign bone lesion of unknown cause. It may occur alone or with other types of benign bone lesions. They usually are located in the long bones and spine in patients less than twenty years old. Typical complaints are swelling and pain which usually follows an injury. X-rays show a clearly outlined, bulging, destructive and eccentric lesion of the bone. The cyst tissue is made of spongy spaces filled with unclotted blood. It is important for these cysts to be distinguished from malignant bone tumors so biopsy is usually required. Treatment is by curettage with bone grafting or resection depending on the location of the cyst. The recurrence rate after currettage approaches 30% and this is one of the reasons for excision when the tumor involves an expendable bone.
Benign Vascular Tumors of Bone
Very rare type of tumor. The benign hemangioma of bone is usually solitary (found only in one bone) but can affect more than one bone. Hemangiomas are found in the spine, skull, long bones and pelvis. Local pain, swelling and pathologic fracture (fracture through the bone tumor) may occur. Isolated spine lesions (tumors) usually do not cause symptoms. On x-ray, the lesions appear as lytic defects (destroyed bone). Hemangioma tissue appears as a honey combed pattern made of a conglomeration of vessels. Treatment is usually observation, but may involve resection or curettage when possible. Radiation is given for painful lesions and those located in difficult areas inaccessible to surgery.
Histiocytosis of Bone or Eosinophilic Granuloma (EG)
A benign disorder of bone involving usually no more than two or three bony sites of children and young adults. Local pain or fracture are the most common presenting symptoms. Destructive-looking lesions are seen on x-ray. Many lesions will disappear if left alone. A biopsy is usually necessary to establish the diagnosis of EG. If the bony defect is large, curettage with bone grafting is sometimes done. Steroid injections have also been successful to treat these bony lesions. There are variations of histiocytosis with more organ involvement and more generalized disease with endocrine abnormalities. Treatment options may include radiation therapy to relieve symptoms, curettage or chemotherapy to treat systemic disease.
Giant Cell Tumor (GCT)
A benign tumor of bone but has the potential to be locally aggressive, meaning that it may recur in the same bone or the soft tissue where the original tumor was excised. The cause of this tumor is unknown. It occurs most often between the ages of 20-40 years. GCT is usually located around the knee, either the distal femur or proximal tibia. The distal radius, proximal humerus, distal tibia and sacrum are other common sites. Unlike other benign lesions, GCT can metastasize to a distant site such as the lungs, but this is rare.
Patients present with a deep, persistent pain in the area of tumor. The rate of the tumor's growth seems to be accelerated during pregnancy because of the increase in hormones. A pathologic fracture may occur, as well as adjacent joint effusions (fluid in the joint). On x-ray, there is thinning and expansion of the cortex, erosion and possible cortex perforation and associated soft tissue mass. The giant cell tumor tissue is very vascular.
Treatment consists of curettage with cement packing. Local recurrences occur in a low percentage of patients, so close follow-up is mandatory. If the tumor is located in the proximal fibula, a resection is done. A wide resection with allograft reconstruction is the treatment of choice for very large, poorly defined tumors with soft tissue mass or pathologic fracture. Although rare, giant cell tumors can spread to the lungs. Thus, a chest x-ray must always be done at follow-up visits in addition to an x-ray of the body part to rule out distant metastases and local recurrence. Treatment for the rare lung metastases involves chemotherapy and resection of the lung nodules.
Benign Soft Tissue Tumors
Soft tissue tumors develop in connective tissue other than bone such as the skeletal muscle, fat, tendon, fibrous tissue and nerve and blood vessel (neurovascular) tissue.
Soft tissue tumors can occur anywhere in the body but are most frequent in the lower extremities, trunk and abdomen and upper extremities. The cause is unknown. Trauma may bring attention to a previous existing tumor.
Benign soft tissue tumors rarely metastasize. They are categorized according to their behavior to be aggressive or not, ranging from inactive, to active, to aggressive.
In adults, the most common benign soft tissue tumor is a lipoma. In children, popliteal (Baker's) cysts, lipomas and hemangiomas are common. Benign tumors may be very large and deep but are usually soft - except for the fibrous tumors which may feel firm.
Types of Benign Soft Tissue Tumors
The most common benign soft tissue tumor made of fat and is usually large and soft. They are located on the back, shoulders, abdomen and upper and lower extremities. They usually do not cause symptoms unless they begin to push on nearby nerves. Lipomas usually grow slowly with little change over many years. Many patients seek medical attention for cosmetic reasons when a lipoma grows too large. An angiolipoma which involves blood vessels usually occurs in children located deep in the muscle and is tender because it involves the vessels. On the MRI scan, the lipoma is seen as a bright, well defined mass. Treatment includes removing (excising) the mass or observing it if it is not bothersome. Recurrences are unusual.
A benign vascular (involving blood vessels) soft tissue tumor. It is the most common soft tissue tumor in children. It can develop in the top skin (superficial) layer or deep within the muscle. They occur more often in the lower extremities than the upper extremities. Hemangiomas can range from being well-defined, noninvasive and involving small vessels (capillaries) to less defined, invasive and involving large vessels. The most common type of hemangioma is made of both large and small vessels. The MRI scan is the best type of imaging to show the location and extent of the tumor. Angiograms may also be done to evaluate the large blood vessels.
Treatment is not necessary unless they cause pain. Aspirin and compression stockings may be quite successful in relieving symptoms. Surgical excision is sometimes necessary if symptoms persist. Although hemangiomas are vascular, they do not spread to other areas or turn malignant. Occasionally for large tumors that can not be removed, radiation therapy and embolization (a procedure to plug/stop the blood supply in the tumor area preventing tumor growth) has been attempted to treat hemangiomas with little success. Recently, treatment has also included injections with alcohol into the tumor (sclerotherapy).
Fibroma & Fibromatosis
Benign soft tissue tumors made of fibrous tissue come in many different forms. Congenital fibromatosis occurs in infants and usually presents as a solitary mass. Fibrous tumors in adolescents and adults include fibromas, extra-abdominal desmoid tumors, palmer fibromatosis and nodular fasciitis. Fibromatosis (desmoid tumor) refers to a benign but aggressive tumor usually located in the lower extremity. Fibromatoses are very aggressive at the original site and invade the nearby muscle, soft tissue and bone but do not metastasize (spread to other sites). MRI scans or CT scans are done preoperatively. Plain x-rays will rule out any bone involvement under the soft tissue mass, and a bone scan will show any other bony invasion.
Treatment includes removal (excision) of the soft tissue mass. In some cases the surgical margin (area around the tumor) is not large enough because the tumor extends microscopically beyond the main mass. Thus, there is a high rate of recurrence. These tumors should be treated aggressively with wide margin excisions. Radiation therapy is also used for local control.
Neurofibroma & Neurofibromatosis
Benign soft tissue tumors that are made of nerve tissue. They are also called nerve sheath tumors or schwannomas because the tumor tissue has cells like the nerve sheath (envelope around the nerve fibers), or Schwann cell. Neurofibromas may occur as a single tumor or many tumors and may be found anywhere on the body. They range from simple, small masses to gross enlargement of an extremity (elephantiasis), to masses causing bony erosion and deformities of the spine. Since neurofibromas come from nerve roots, those located in the spine can press on the spinal cord causing neurologic symptoms.
Neurofibromatosis is an inherited syndrome and is the most common genetic disorder, usually diagnosed in childhood. The patient presents with greater than six cafe au lait spots ('coffee with milk' colored, brownish, birthmark spots on the skin) and/or many neurofibromas (called von Recklinghausen's disease) over their entire body. Patients with severe disease may have large neurofibromas involving an entire extremity.
An MRI scan is necessary to evaluate the size and extent of the neurofibroma. The mass is usually seen in connection with a major nerve. Examination of the tumor tissue shows a tumor composed of spindle cells. The treatment involves excision of neurofibromas if they are large, painful or interfere with function. Single neurofibromas once excised rarely recur. The multiple neurofibromas of neurofibromatosis may become malignant. Most often they are observed and not excised unless they are growing or painful. If a sarcoma develops, the patient must undergo staging studies to rule out metastatic disease. Pre- and/or post-operative radiation therapy is usually included in the treatment plan, and sometimes chemotherapy.
Pigmented Villonodular Synovitis (PVNS)
A benign soft tissue mass involving the synovial membrane (lining of a joint). It is most often seen in the knee or hip joint of adults under age 40. Patients usually present with a boggy, swollen, painful joint. The synovial membrane becomes thick. Many times the disease process goes beyond the joint and causes severe degenerative joint disease. If an aspirate (fluid withdrawn from an area with a needle) of the joint is done, it will show a bloody, brown fluid. Other diagnoses that must be ruled out are infection, rheumatoid arthritis, hemangioma, giant cell tumors of tendon sheath or malignant synovial sarcoma. X-rays of PVNS show an increase in joint fluid, a thick synovial membrane and sometimes bone erosion. Bone scans show increased activity in the joint area, and synovial thickening and nodularity or a mass are seen on the MRI scan. A biopsy should be performed on large nodular tumors to rule out sarcoma. Tumor tissue reveals many rounded synovial-like cells with a good amount of giant cells and inflammatory cells. Treatment involves an excision of the tumor. If the PVNS is widespread, a complete synovectomy (excision of the membrane that lines joints lubricating them with fluid) must be done. Localized nodular synovitis is simply excised. PVNS may recur unless the entire synovial membrane is removed. Widespread PVNS usually causes chronic degenerative joint disease which may require total joint replacements. Radiation is an alternative adjuvant therapy in recurrent cases.
A non-tumorous soft tissue mass that occurs after a blunt trauma. The soft tissue reacts to the trauma by forming a bony mass. Patients present with a painful or painless mass which is increasing in size. The tumor is usually located in the upper arm, thigh or buttock. X-rays show a round ossified (bony) mass which may be read as a sarcoma. However, the myositis ossificans has a distinct margin of ossification (bone formation) with an active center containing immature cells. Sarcomas have active and inactive tissues on the outer margin with an inactive center. Bone scans show increased activity in the area of the mass for about 8-12 weeks, and then the activity decreases. The CT scan is the best imaging to show the bony mass. Treatment involves observation or excision usually after an 8-12 week period because if it is excised before full maturation, recurrence is likely. There lesions sometimes resolve without treatment.
Ganglion or Synovial Cyst
A benign soft tissue mass 'cyst like' in nature and comes from the capsule of the joint, synovial membrane (lining) or tendon sheath (covering). It usually develops on the top of the wrist in adults between 25 and 45 years of age, and are more common in women. The cause is unknown, but repeated trauma is a contributing factor. Some patients have no symptoms, while other have tenderness, pain and problems with wrist function. A needle aspiration should be done if a sarcoma is suspected. Staging studies are usually not necessary because of the ganglion cyst's classic appearance, although ultrasound is helpful in confirming the cystic nature of the lesion. The excised cyst or nodule has an outer fibrous layer with an inner lining made of clear colorless, gelatin-like fluid.
Some ganglia need no treatment because they go away on their own. Usually needle aspiration or rupture of the cyst give temporary relief. Recurrence is common. The best treatment for a patient who has symptoms is to completely excise the cyst down to the base of the cyst which should prevent recurrence. Baker's cysts behind the knee in children nearly always resolve without treatment.
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