Introduction
The lymphatic system plays a major role in the body's immune system, which helps fight infections and diseases. It mainly comprises the spleen, bone marrow, thymus gland, and lymph nodes. It not only protects one from infections but also helps in maintaining fluid balance in the body. The lymph system consists of cells called lymphocytes. Uncontrolled excessive growth of cells that may spread rapidly throughout the body is referred to as cancer. When this cancer takes place in the white blood cells, namely the lymphocytes, it is referred to as lymphoma. There are two main types of lymphocytes:
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T-lymphocytes.
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B-lymphocytes.
Each of these types plays a unique role in the well-being of one’s immune system. Lymphoma is subdivided into two general categories based on the presence of special cells referred to as Reed-Sternberg (RS) cells. These RS cells are neoplastic (abnormal cells or tumor cells) with characteristic mirror-image nuclei (similar to owl eyes).
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Hodgkin’s lymphoma also referred to as Hodgkin's disease.
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Non-Hodgkin's lymphoma.
Further diagnosis is facilitated by determining whether the tumor originated from T-cells or B-cells. The primary bone lymphoma usually belongs to the non-Hodgkin’s category with an emphasis on B-type origin. The rest of the article discusses the causes, symptoms, and diagnostic approaches implemented for primary bone lymphoma.
What Entails Primary Bone Lymphoma?
Primary lymphoma of bone (PLB) is characterized by destructive bony lesions reported to originate in the bones comprising red bone marrow. Examples include the pelvis, ribs, femur, and the humerus. The incidence of PLB is found primarily in people aged 30 years or above; however, there are no specific age criteria described in the scientific literature. Anyone can suffer from PLB irrespective of age, with men being more likely to acquire the disease compared to women. The incidence of PLB is quite rare. Comparatively speaking, malignancies that start elsewhere and spread to the bone during their growth are more common than those that start in the bone itself.
What Causes Primary Lymphoma of Bone?
The exact cause for the occurrence of primary bone lymphoma is not yet known but many factors may play a role in its pre-disposition. Some of them are listed below:
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Age: PLB is more prevalent in people aged 30 years or above.
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Sex: Males are predominantly at a higher risk of getting PLB than females.
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Epstein-Barr Virus (EBV) Infection: People who have had an EBV infection in the past are more at risk of getting PLB than others.
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HIV Infection: People with HIV (human immunodeficiency virus) infection are more prone to suffer from PLB.
What Are the Symptoms of Primary Bone Lymphoma?
The most common symptom of primary bone lymphoma is pain. Sharp shooting pain is experienced at the site of the tumor and is consistent at all times of the day, even at rest.
The concerned bone is said to weaken in structure over time, ultimately resulting in a fracture. Often, the diagnosis of PLB is made owing to the doctor visit post-fracture. The physical examination and lab tests carried out to treat the fracture reveal the presence of cancer in the body. Weight-bearing bones like the femur and spine are more prone to fractures compared to other bones.
Other generalized symptoms of PLB include:
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Tiredness and fatigue.
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Weight loss.
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Feeling ill and weak for most parts of the day.
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Fever may be present.
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Night sweats are common.
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Neurological symptoms such as numbness in the lower extremities, or tingling sensation may appear in cases where the tumor presses on spinal structures.
How Is Primary Bone Lymphoma Diagnosed?
1. The first approach to diagnosing the lymphoma is to ask the patient about the medical history and relevant family history. Secondly, the doctor performs a thorough clinical assessment of the painful site, which possibly indicates the presence of a tumor. The clinician examines for any tenderness over the bone, signs of swollen lymph nodes, or a hard mass of tissue in the area inflicting pain. Once the clinical assessment is completed, the doctor orders further laboratory tests and imaging tests to confirm the diagnosis of the disease.
2. The laboratory tests mainly include specific blood tests that can indicate the blood count, the absence or presence of any inflammatory markers, the level of electrolyte present in the blood, and specific abnormalities that may point towards cancer.
3. The imaging tests are ordered to assess the internal structure of bone, and the amount of bone involvement present. An X-ray aids in identifying the characteristic bony lesions of primary bone lymphoma. Typical radiographic findings of the bone include:
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The moth-eaten appearance of the bone; the visual image of the bone appears to be mottled.
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An enlarged overgrowth or a soft tissue mass surrounded by the non-destructive bone is present.
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Deformity of the bone due to the expansion of the tumor.
4. If the doctor is not satisfied with the results of an X-ray, more advanced imaging tests such as an MRI scan (Magnetic resonance imaging), CT scan (computed tomography), or PET scan (Positron emission tomography) may be ordered to obtain an accurate diagnosis. A definitive diagnosis can be made by performing a bone biopsy. This typically involves the resection of a small portion of the tumor, followed by skillful examination under a microscope. In case of a positive lymphoma, the microscopic evaluation will include multiple small, round, blue cells. The diagnosis procedure of primary bone lymphoma is hefty and poses a challenge even for the best clinicians. However, following a proper sequence and assuring a thorough work-up at every step of the procedure can increase the likelihood of obtaining a prompt and accurate diagnosis. Once the diagnosis of PLB is established, further tests are carried out to identify the stage of the tumor. This not only informs the doctor of the tumor condition but also aids in evaluating the best treatment plan necessary to achieve a fair prognosis.
How Is Primary Bone Lymphoma Treated?
The management of PLB involves a multi-directional approach. Depending on the staging of the tumor, the doctor may advise:
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Chemotherapy: This may be present with or without radiation. The commonly used agents include cyclophosphamide, doxorubicin, vincristine, and prednisone. Rituximab may also be prescribed in some cases.
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Radiation Therapy: This typically involves the use of X-rays to target the cancerous tumor cells, and kill them, all the while preserving the surrounding healthy cell and tissue structure. A radiation oncologist is the designated person to carry out this treatment.
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Surgical Resection: This mode of treatment is rarely opted for in cases of primary lymphoma of bone. However, it may be recommended to surgically intervene in cases where bone fracture is inevitable or has already occurred. The orthopedic surgeon heals the fractured bone by the insertion of metal rods and plates. Strengthening of the bone and the attached structures is later carried out under the supervision of a physical therapist.
Conclusion
To summarize the above article, primary bone lymphoma is an extremely rare case scenario. The main symptom of PLB is pain at the site of the tumor. Radiographic evaluation indicates the presence of an abnormal swelling or soft-tissue mass surrounded by normal bone structure. The treatment plan is determined based on the staging and severity of the tumor. The prognosis highly depends on the age of the patient, the stage of the tumor upon initiating the therapy, and last but not least, the skillful expertise of the doctor. Regular follow-ups post-completion of therapy must be carried out to check for bone health or any signs of relapse. It is possible for the tumor to re-grow despite proper administration of the treatment.
