Definition and Classification
Bone lymphoma accounts for about 7% of all malignant bone neoplasms and 5% of all extranodal lymphomas. The disease includes both Hodgkin lymphoma and non-Hodgkin lymphomas (NHL), accounting for 3% to 9% of all childhood NHL cases. Bone involvement accounts for less than 2% of all adult lymphomas.
The key concept is primary bone lymphoma (Primary Bone Lymphoma, PBL). Establishing this diagnosis requires meeting a strict criterion: it must be an isolated bone lesion (with or without regional lymph node involvement) with a complete absence of distant foci for 6 months from the time of manifestation.
Multifocal primary lymphoma is also distinguished. It is less common (accounting for 11% to 33% of all cases) and involves two or more bone sites. In the multifocal form, no extraosseous lesion or lymph node involvement should be detected within the first 6 months after diagnosis. Patients typically present with localized bone pain and a palpable soft tissue mass.
Radiographic and CT Findings
The tumor is most frequently localized in the diaphysis or metadiaphysis of long tubular bones (humerus, femur, tibia). However, epiphyseal lesions involving adjacent joints, as well as isolated involvement of flat bones or the spine, can also occur.
On radiographs and CT scans, the pathology manifests with the following characteristic patterns:
- Bone destruction is permeative (permeative) in character or appears as a "moth-eaten" (moth-eaten) pattern.
- A pronounced aggressive periosteal reaction is observed in 50% of cases.
- Osteoblastic (osteosclerotic) foci are atypical and occur in only 2% of observations.
- Bone marrow space involvement may be radiographically occult (occult).
- In 17–22% of cases, aggressive tumor growth leads to pathological fractures.
When flat bones, such as the pelvic bones, are involved, axial CT slices reveal extensive destruction (particularly of the ilium) with the formation of a large circular extraosseous component and the appearance of multiple bone sequestra.
MRI and Radionuclide Diagnostics
Magnetic resonance imaging is the optimal method for visualizing the soft tissue component accompanying the tumor. The mass itself may demonstrate a non-specific MRI signal, but a relatively low signal intensity on T2-weighted images (T2WI) is considered a recognized characteristic pattern.
The pattern of diffuse skeletal involvement on MRI appears as a generalized decrease in signal intensity on T1WI and a marked increase in bone marrow signal in the STIR sequence. In primary multifocal lymphoma, sagittal STIR images may visualize multilevel infiltration of the vertebral and sternal bone marrow. Concurrently, enlarged regional lymph nodes may be identified on the scans.
Whole-body scanning methods are used to accurately assess multifocal involvement:
- Whole-body MRI.
- Skeletal scintigraphy.
- PET-CT (positron emission tomography) — allows for the clear identification of multifocal zones of active fluorodeoxyglucose uptake (FDG avidity).
Differential Diagnosis of Hematological Neoplasms
In diagnostic imaging, it is important to distinguish lymphoma from other hematological bone pathologies:
- Leukemia (Leukaemia): on MRI in STIR mode, it may present with osteonecrosis (e.g., humeral head) with subchondral fractures and the development of bone marrow infarcts (e.g., in the scapula).
- Myeloid Sarcoma (Myeloid Sarcoma): on MRI (PDW FSE mode), extraosseous spread of tumor tissue from the destroyed bone (e.g., ulna) into the surrounding soft tissues is clearly delineated.
- Plasma cell dyscrasias: a group of B-cell-derived disorders including monoclonal gammopathy of undetermined significance (MGUS), smoldering myeloma, and symptomatic multiple myeloma.
Briefly: answers to topical questions
Which histological variants of non-Hodgkin lymphoma can primarily affect bones?
Primary bone involvement is almost always represented by non-Hodgkin lymphomas, accounting for about 1% of all cases of this disease. The following histological variants are most commonly responsible for primary bone involvement:
- Diffuse large B-cell lymphoma (DLBCL) is the most frequent histological type.
- Follicular lymphoma also occurs in primary involvement, but less frequently.
Both variants typically affect large long tubular bones (femur, tibia, humerus) in the metadiaphyseal or diaphyseal region.
By which radiographic criteria is bone lymphoma differentiated from Ewing sarcoma and osteosarcoma?
According to the cited sources, bone lymphoma typically presents with moth-eaten or permeative destruction; an aggressive periosteal reaction is observed in approximately 50% of cases. A large soft tissue mass is present in 50–75% of patients. Ewing sarcoma is characterized by permeative destruction, multi-layered periosteal reaction, extraosseous component, and cortical saucerization. The cited sources do not specify particular radiographic criteria for osteosarcoma to compare with lymphoma.
How is the response of primary bone lymphoma to therapy evaluated using the Deauville scale on PET-CT?
Lymphoma response to therapy is evaluated using the 5-point Deauville scale based on the intensity of fluorodeoxyglucose uptake compared to the mediastinal blood pool and liver:
- 1 point — no uptake.
- 2 points — uptake ≤ mediastinal blood pool (corresponds to complete metabolic response).
- 3 points — uptake > mediastinum, but ≤ liver.
- 4 points — moderately increased uptake compared to the liver (corresponds to partial metabolic response).
- 5 points — markedly increased uptake compared to the liver (>3 times) and/or new lesions.
- X — new zones of uptake likely unrelated to lymphoma.
Class and exam questions
What is characteristic of the MRI appearance of bone lymphoma?
A typical sign is the relatively low signal intensity of the tumor on T2-weighted images. Diffuse bone marrow involvement shows decreased signal on T1WI and increased signal on STIR.
In which parts of the bone is primary lymphoma most frequently localized?
In 70% of cases, the tumor arises in the metadiaphysis or diaphysis of large long tubular bones, such as the femur, tibia, and humerus.
How does bone lymphoma appear on radiographs?
Bone destruction is most frequently identified as a moth-eaten or permeative pattern. Additionally, an aggressive periosteal reaction is observed in half of the patients.
What else to study on this topic
- Radiological Semiotics of Plasma Cell Dyscrasias and Multiple Myeloma
- Features of MRI Diagnostics in Myeloid Sarcoma and Leukemic Involvement
- Prognostic Significance of the Soft Tissue Extraosseous Component
- The Role of PET-CT in Staging Skeletal Hematological Neoplasms
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete Guidelines on "Bone Lymphoma" and 2,199 More Pages of the Subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the "Diagnostic Radiology in Oncology" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.