Treatment of Benign and Malignant Tumors of the Bone

A tumor is an abnormal tissue mass that forms when the cells in our body start dividing uncontrollably or do not die when they are supposed to. Musculoskeletal tumors are tumors that develop in muscles, bones and nerves. They can be classified as benign or malignant, and primary or secondary in nature. A benign tumor is a non-cancerous growth that does not intrude nearby tissues or spread to other parts of the body. A malignant tumor is cancerous destroying nearby tissues and can spread to other parts of the body. Primary malignant musculoskeletal tumors originate in muscle or bone whereas secondary tumors have spread from elsewhere in the body to the muscles or bones.

In order to understand more about musculoskeletal tumors, they can be broadly divided into two major groups namely bone tumors and muscle tumors. Each of these groups is further classified as benign or malignant. The most common benign bone tumors are endochondroma, osteochondroma, nonossifying fibroma, chondroblastoma, osteoid osteoma, osteoblastoma, periosteal chondroma, giant cell tumor, and chondromyxoid fibroma. Malignant bone tumors, although less common, include two subtypes namely primary malignant tumors such as osteosarcoma, chondrosarcoma and Ewing’s sarcoma and secondary metastatic tumors that metastasize from the carcinoma of the lung, breast, prostate, kidney or thyroid gland. Benign tumors that arise in the muscles are leiomyomas and rhabdomyomas. Malignant muscle tumors are called leiomyosarcomas and rhabdomyosarcomas.

Bone Tumors

Benign Bone Tumors

Benign bone tumors occur most commonly among people below 30 years. They can develop in any bone but most commonly the femur, tibia, humerus and pelvis bone are involved. A lump or swelling that can be felt by touch is usually the first sign of a benign tumor. There will be increasing pain in the region of the tumor which persists over some time. In some cases, the tumor remains undiscovered until there is a fracture in the bone that has become weak from a growing tumor.

Endochondroma

Endochondroma is a benign bone tumor that may occur at any age but tends to be commonly seen in people between 10 and 40 years. It arises inside the bone. This tumor has no symptoms in early stages but may enlarge and become painful later. They are often discovered on X-ray taken for a different purpose. X-ray, MRI and CT scan may be done for the diagnosis and if there is pain, then biopsy is done to confirm the diagnosis. If there is no pain or other symptoms, biopsy, excision or curettage is not necessary, however follow-up imaging tests will be advised every 6 months to preclude progression of the tumor.

Osteochondroma

Osteochondroma, the most common type of benign bone tumor, may develop in any bone but commonly occurs at the ends of the long bones. This tumor is commonly seen in people between 10 and 20 years. Diagnosis is done by imaging studies in which the tumor appears as a bony prominence having a cartilage covering and no cortex underlying the prominence.

Surgical excision of the tumor is indicated only if the growth compresses a large nerve or is causing pain or growth disturbances, and imaging study suggests a malignant transformation.

Chondroblastoma

Chondroblastoma is a rare tumor and occurs among people aged between 10 and 20. It develops at the epiphyseal region of the bone and spreads across the bone destroying the entire bone and joint. Diagnosis is confirmed by MRI scan which can differentiate the lesion. Surgical removal of the tumor is performed by curettage and the residual cavity is filled by bone graft placement.

Osteoid Osteoma

Osteoid osteoma can affect any bone but is more common in long bones. It is seen often in young people between 10 and 35 years. It causes pain which is often severe at night. If it occurs in children of growing age, the inflammatory response and increased circulation of blood near the open growth plates may result in overgrowth and limb length discrepancy. Imaging studies, technetium-99m bone scan and CT scan will be done to differentiate the lesion. Osteoid osteoma is commonly treated by percutaneous radiofrequency ablation procedure done by an interventional radiologist.

Giant Cell Tumors

Giant cell tumors commonly occur in the second or third decade of life and arise in the epiphysis gradually eroding away the remaining bone to extend into the soft tissues. They have a tendency to recur and can also cause pain. Treatment for benign giant cell tumors involve curettage and packing with methyl methacrylate or bone graft. Sometimes, thermal heat provided by methyl methacrylate or chemically by phenol and freezing with liquid nitrogen reduces recurrence of the lesion. Complete excision of the tumor is performed if the tumor is too large.

Malignant Tumors

Malignant bone tumors are rare compared to benign tumors but are very dangerous as they tend to spread from the site where they initially develop. The tumor cells enter the blood stream or travel through lymph vessels and spread to other sites. Lungs are the most common sites where malignant tumors spread.

Osteosarcoma is the most common bone cancer and occurs in people between the age of 10 and 30. It often develops in the arm and leg bones, and pelvis. It may metastasize to lungs or other bones. Symptoms such as pain and swelling may be present.

Diagnosis is based on imaging studies and biopsy. A chest X-ray and CT scan may be ordered to check for lung metastasis. Bone scan may be done to determine bone metastasis.

The treatment involves a combination of chemotherapy and surgery. Chemotherapy is given for several months before limb sparing surgery and limb reconstruction is performed. During limb sparing surgery, the entire tumor is removed along with the encircling reactive tissue and normal tissue at the edges. Chemotherapy is continued after the surgical removal of the tumor.

Chondrosarcoma

Chondrosarcoma is the second most common type of malignant bone tumor. It involves the cartilage cells and is commonly seen in older adults. It rarely occurs in young people below 20 years or in the elderly above the age of 75. It occurs in the arm bones, legs, pelvis and the ribs. Usually this cancer arises in the normal cartilage, but may also form within a benign cartilage tumor called osteochondroma.

Diagnosis involves X-ray imaging, screening study such as technetium-99m bone scintigraphy and biopsy to determine the grade of the tumor.

Treatment involves wide curettage for low-grade chondrosarcoma. An adjuvant such as freezing liquid nitrogen, argon beam, heat of methyl methacrylate, radiofrequency or phenol may be used. Surgical resection is done for other tumors because chemotherapy and radiation therapy are less efficacious in treating chondrosarcoma.

Ewing's Sarcoma

Ewing's sarcoma develops in the bone cavity, often in the mid portion of the long bones of the legs and arms. This cancer is common in childhood and is very rarely seen in adults above 30 years of age. The most common symptoms include pain and swelling.

Diagnosis includes X-ray with MRI scan to determine the extent of the disease. A biopsy may be done to differentiate the lesion from other tumors. The treatment involves a combination of chemotherapy, radiation therapy and surgery. Often, chemotherapy in conjunction with surgical resection gives good results.

Secondary or Metastatic Bone Tumors

Secondary or metastatic bone tumors may develop from spread of carcinoma of the breast, lung, prostate, kidney, thyroid and colon. Breast cancer is the most common cancer that has a tendency to metastasize to the bone. Pain in the affected bone is the main symptom of metastasis and may appear even before the primary tumor has been detected. Diagnosis is made by X-ray, radionuclide whole-body scanning and needle biopsy of the lesion.

Treatment usually includes radiation therapy, and surgery to stabilize weakened bone at risk of fracture. Radiation therapy in combination with chemotherapy or hormonal drugs is the most common treatment plan. If there is large area of bone destruction, then surgical fixation or resection followed by reconstruction is performed.

Muscle Tumors

Muscles are of 2 types namely smooth muscles and skeletal muscles. Smooth muscles are involuntary muscles that are not under our control and are found in organs such as stomach, intestines, blood vessels or uterus. Skeletal muscles or striated muscles allow movements of our arms and legs and other parts of the body.

Benign muscle tumors are of two types called leiomyomas and rhabdomyomas. Leiomyomas arise in the smooth muscles and develop in the walls of blood vessels. Most commonly, they are found in the uterine wall and are called fibroids.

Rhabdomyomas are benign tumors of the skeletal muscles and are rare.

Malignant muscle tumors include leiomyosarcomas and rhabdomyosarcomas. Leiomyosarcomas are malignancies arising in the smooth muscles and often occur in internal organs, blood vessels and at the back of the abdominal cavity. They occur in adults especially at an elderly age.

Rhabdomyosarcomas are cancers that consist of cells that would normally develop into skeletal muscles. This tumor commonly affects children rather than adults. The arms, legs, head and neck region, urinary and reproductive organs such as vagina, bladder and prostate gland are the common sites where this tumor may occur.

The two main subtypes of rhabdomyosarcomas include embryonal rhabdomyosarcomas and alveolar rhabdomyosarcomas. Embryonal rhabdomyosarcoma affects infants and young children. It occurs in the head and neck region, bladder, vagina or prostate. Alveolar rhabdomyosarcoma affects teenagers and older children. Often, large muscles of the arms, legs and abdomen are affected. Treatment involves surgery to remove the tumor prior to which chemotherapy or radiation therapy may be used to shrink the growth.