Lymphoma is a blood cancer that affects the lymphocytes, a kind of white blood cell. The two main kinds of lymphoma are Hodgkin’s lymphoma and non-Hodgkin’s lymphoma, or NHL. Though lymphomas usually begin in the lymph nodes, they can arise virtually anywhere in the body. When they arise outside the lymph nodes, they are called extranodal lymphomas. Primary bone lymphoma is an uncommon extranodal lymphoma. When a lymphoma starts outside of the lymph nodes, it is much more common for the malignancy to begin in the gastrointestinal tract than in the bone.
Primary bone lymphoma is an extremely rare condition in which a lymphoma starts in the bones. This condition accounts for about 1 to 2 percent of all cases of non-Hodgkin lymphoma, with a higher incidence of 3 to 9 percent in children and adolescents. Cancers that start elsewhere and then spread to the bones are much more common than primary bone lymphoma.
Who Is Affected?
Primary bone lymphomas mainly affect adults. Males are more likely to be affected than females. Most are non-Hodgkin lymphomas of the large B-cell type, for which the number of cases peaks between ages 45 and 60. However, when it comes to the bottom of the spine at the sacrum or tailbone, primary bone lymphoma has a peak incidence in the teens and twenties. And rare cases occur in children with a mean age of 12 years.
Most people affected by primary bone lymphoma first feel pain in their bones. Often the pain is felt even at rest. This may persist for months before any other symptoms arise. When the lymphoma grows bigger, it can cause a swelling of the limb and limit movements of the arm or leg. Other symptoms of lymphoma such as fever and weight loss are not common.
Diagnostic imaging, X-rays, and scans of the bone help detect primary bone lymphoma. A tumor of the bone shows characteristic changes in the appearance of the bone on MRI or CT scans. There can be a moth-eaten pattern of bone destruction in areas affected by the lymphoma.
To determine the type of tumor, a biopsy of the bone is done. This can be done surgically, by taking a small piece of the tumor-involved bone for microscopic examination. Other tests help determine whether the tumor is widespread or limited to the bone. PET/CT of the chest, abdomen, and pelvis may be used to determine the extent of lymph node involvement and the presence of distant disease.
Most commonly, primary bone lymphoma is non-Hodgkin lymphoma or NHL. Hodgkin lymphoma of the bone is much less likely. Among the different types of NHL, diffuse large B-cell lymphoma, or DLBCL, is the most common primary bone lymphoma. The type of lymphoma guides decisions about the kind of treatment that might be pursued.
Because primary bone lymphoma is so rare, a single optimal treatment regimen has not been established. Current treatments usually consist of chemotherapy for a few cycles in combination with radiation therapy to the bone. Treatment on a number of different fronts, or multimodal therapy, is common, however, the sequence of radiation and chemotherapy varies in published reports. Survival rates for primary bone lymphomas are often better than for other forms of non-Hodgkin lymphoma.
The University of Miami reports over 80 percent of people treated for primary bone lymphoma are without progression of their disease 4 years later — they found an 83 percent progression-free survival, or PFS in a study of 53 patients. No difference was seen between patients treated with chemotherapy or combined chemotherapy plus radiation. However, there was a trend toward improvement in PFS for patients with DLBCL treated with rituximab plus chemotherapy.
A Word From Get Meds Info
After treatment, PET/CT scans may be particularly useful to assess the response to therapy. The post-treatment imaging study of choice is the PET/CT scan, which helps distinguish persistent disease from fibrosis. Patients should also be monitored for long-term relapse. Bone lymphoma has a low rate of local relapse and most often it recurs at distant locations from the original disease.