|Year : 2016 | Volume
| Issue : 2 | Page : 57-59
Radiation therapy of a Non-Hodgkin's lymphoma presenting as mass in the knee
Pinelopi-Theopisti Memtsa1, Konstantia Loga2, Ariadni Kyriakogiannaki3
1 Department of Radiation Oncology, AHEPA Hospital, Aristotle University, Greece
2 Department of Medical Oncology, Theageneio Anticancer Hospital, Thessaloniki, Greece
3 Department of Radiation Oncology, Alexandra Hospital, Athens, Greece
|Date of Web Publication||7-Oct-2016|
Department of Radiation Oncology, AHEPA Hospital, Aristotle University
Source of Support: None, Conflict of Interest: None
Non-Hodgkin's lymphoma (NHL) represents a group of malignancies of the lymphatic system which are characterized by uncontrolled proliferation of B- or T-lymphocytes. NHL may affect the musculoskeletal system in 5-25% of the patients. In this case, we present a case of a patient who underwent surgery, in which a soft tissue mass was removed from the popliteal cavity of the right knee. After a series of examinations, it was considered to be a follicular B-cell NHL of the knee which was successfully treated with radiation therapy.
Keywords: Knee, non-Hodgkin′s lymphoma, radiation therapy
|How to cite this article:|
Memtsa PT, Loga K, Kyriakogiannaki A. Radiation therapy of a Non-Hodgkin's lymphoma presenting as mass in the knee. J Radiat Cancer Res 2016;7:57-9
|How to cite this URL:|
Memtsa PT, Loga K, Kyriakogiannaki A. Radiation therapy of a Non-Hodgkin's lymphoma presenting as mass in the knee. J Radiat Cancer Res [serial online] 2016 [cited 2023 Feb 5];7:57-9. Available from: https://www.journalrcr.org/text.asp?2016/7/2/57/191710
| Introduction|| |
on-Hodgkin's lymphoma (NHL) is a malignancy of the lymphatic system which may affect the musculoskeletal system in 5-25% of the patients and joints, in particular, in even rarer cases. Intra-articular lymphoma can either affect the bones or the soft tissues within the joint. These cases can be found incidentally in otherwise asymptomatic patients and can be discovered through arthroscopy. 
There are reports in literature concerning patients with lymphoma of the knee, shoulder, and elbow. As the treatment options of these patients are still debated, we present a case of a patient with follicular B-cell NHL of the knee which was successfully treated with radiation therapy.
| Case Report|| |
A 51-year-old man was referred to our hospital complaining of pain and rigidity in the right popliteal region which lasted for the past 6 months. The patient underwent triplex ultrasound of the venous system of the right leg which revealed a solid mass on the posterior surface of the right knee. The mass was well circumscribed, highly hypoechoic, and vascularized, and its dimensions were 2 cm × 1.6 cm × 1.3 cm. There was also a 0.9 cm lymph node next to the mass.
The patient underwent surgery, in which the soft tissue mass was removed from the popliteal cavity of the right knee. The maximum diameter of the mass was 3.7 cm. A 2 cm lymph node was also recognized. Histology showed a follicular B-cell lymphoma (BCL). According to the WHO criteria (2008), the excised mass was classified as Grade 2. Immunochemistry showed that the lymphoid cells were positive in CD20 and BCL6 while there were also many tumor cells positive in BLC2 found in nodes inside the adipose tissue. Tumor cells were unequally positive in CD10, but negative in CD3 and CD5. The latter two antigens demonstrate the expected population of small T-cells which were obviously reactive. Myelogram and osteomedullary biopsy confirmed the diagnosis of a follicular NHL with a Follicular Lymphoma International Prognostic Index score 0 (low). A positron emission tomography/computed tomography examination was performed for staging which demonstrated abnormal 18 fludeoxyglucose uptake in a nodular mass in the right knee joint. Thus, the stage of the disease was considered to be as IA due to its solitary site.
The patient was referred to the radiotherapy department for involved-field radiation therapy, with a total dose volume of 30 Gy in 15 sessions with a daily dose volume of 2 Gy [Figure 1] and [Figure 2]. The therapy was performed with two fields (right and posterior) in a linear accelerator with 6 MV energy and 0.7 cm margin from the tumor so that the functionality of the joint is not compromised. The patient is followed up with magnetic resonance imaging (MRI) and clinical examination for every 3-6 months. To the present time, 3 months after radiation therapy, the disease shows a complete response. The two stages are described as follows:
I. Image 1: Radiation therapy contouring
II. Image 2: Three-dimensional presentation of the dose distribution.
| Discussion|| |
NHL represents a group of malignancies of the lymphatic system which are characterized by uncontrolled proliferation of B- or T-lymphocytes. According to the 2008 WHO classification system of tumors of hematopoietic and lymphoid tissues, follicular lymphoma (FL) is a part of mature B-cell NHLs and is graded into three categories (Grades 1-3). 
The genetic basis of FL is the translocation between chromosome 14 and 18 (t (14;18)) and overexpression of BCL2 oncogene. However, this translocation is not present in some Grade 3B FLs. Another genetic change found in FL is a deletion of 1p36 chromosome, which is associated with disease of the inguinal region. Even these forms of disease which are t (14;18)-negative are still considered to be a part of the group of FL. 
NHL may affect the musculoskeletal system in 5-25% of the patients. It may take the form of bone lesions or intra-articular soft tissue proliferations causing arthritis. Bone lesions usually cause articular pain and can be detected by imaging techniques. Regarding the intra-articular form of NHL, there are some cases reported with NHL of the elbow, shoulder, and knee. , The clinical presentation of such cases may simulate rheumatoid arthritis (RA) or coexist with RA. Arthroscopy usually discovers abnormal tissue, and biopsy poses the diagnosis. 
There is a reported association between rheumatic diseases and B-cell NHL. Systemic lupus erythematosus, RA, and Sjogren syndrome are the risk factors for the development of B-cell NHL, especially when presenting in male, older patients, with detectable autoantibodies, systematic and severe disease, and long disease course. The most common types of NHL described in patients with these autoimmune diseases are diffuse large BCL and marginal zone lymphoma. 
Imaging plays an essential role in the evaluation of patients with joint lymphoma, both for diagnosis and staging. Computed tomography is better than plain radiographies in evaluating the extent of disease, and MRI is very helpful in demonstrating bone involvement in NHL. There are reports of cases where NHL was discovered after histologic analysis of resected bone parts during arthroplasties. Patients may be asymptomatic, and laboratory examinations may be unremarkable. Thus, any resected tissue that seems unusual should be examined histologically. 
In other patients, NHL presented with malignant synovitis of the knee which was diagnosed by biopsy after arthroscopy. In general, lymphoma must be included in the differential diagnosis in every patient with constant pain or poor response to conventional treatment. 
There is no consensus regarding the best treatment protocol. Several considerations should be taken into account including age, stage, and prognostic scores. However, when there is localized disease, it can be cured only by local irradiation. According to the general dose guidelines of the NCCN version 2013 for the FL, the overall dose should be 24-30 Gy, and it has to be followed by observation for every 3-6 months for 5 years and then annually or as clinically indicated. 
| Conclusion|| |
Although primary articular lymphoma is rare, attention should be drawn to patients with unusual history, constant pain which does not respond to usual treatment, and suspicious findings in imaging or arthroscopy. Histologic examination must always be performed in suspicious cases to exclude malignancy. Radiation therapy has excellent results in these cases, and it is the treatment of choice.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]