Multifocal large B-cell bone lymphoma

Clinical History

46-year-old male patient presented with a 5-month history of pain in the lower limbs that started in the right foot, then followed by the left foot and both knees.
He also reported pain in both hands for 2 months associated with night sweating and weight loss of 20 kilograms over 5 months.

Imaging Findings

X-ray right foot: Juxta-articular osteopaenia involving tarsals, metatarsals and phalanges.

CT right foot: multifocal areas of bone destruction with extra-osseous soft tissue component.

MRI right foot: Multifocal areas of predominantly well-defined abnormal marrow signals appearing hypointense in T1WI and hyperintense in STIR. Post-contrast shows subtle enhancement of a few of the bony lesions and subtle area of extra-osseous soft tissue component.

4 months later X-ray right foot: Increasing ill-defined osteolytic lesions involving all the bones of the foot.

CT lower limbs: Multiple small well and ill-defined lytic areas in the bilateral femoral and tibial condyles and patella.

CT-guided biopsy reveal diffuse large B-cell lymphoma.

CT neck, chest, abdomen and pelvis are negative for any primary mass lesions or lymphadenopathy.

Discussion

Primary lymphoma of the bone is a rare extranodal presentation of non-Hodgkin’s lymphoma.
It accounts for approximately 3% of malignant bone neoplasms and comprises less than 5% of all extranodal non-Hodgkin’s lymphomas.
Multifocal large B-cell lymphoma is the most common subtype of non-Hodgkin's lymphoma. [1]
It is a very fast-growing and aggressive disease.
It is more common in middle-aged men and in Caucasians.

Primary lymphoma of bone manifests with insidious and intermittent bone pain that can persist for months.
Patients can also have what are classically called "B symptoms" which include fever, night sweats and weight loss. [2]

The radiological appearance of bone lymphoma is variable and nonspecific.
It varies from focal lytic lesions with geographic margins to mixed sclerotic/lytic lesions to diffuse permeative processes with cortical destruction and soft tissue involvement. [1]

Permeative or moth-eaten appearance in metadiaphysis is not unique to lymphoma and can be seen in osteosarcoma, metastasis or Ewing sarcoma.

CT is more sensitive than plain radiography for cortical breakthrough and soft tissue infiltration but its main role is in ruling out nodal disease or other soft tissue involvement in chest and abdomen.

MRI is a useful diagnostic tool to show uniform diffuse infiltration of the bone marrow. Demonstration of tumour spread beyond the bony cortex without disruption of the outline of the bone (wrap around sign) favours the diagnosis of lymphoma rather than metastasis or multiple myeloma. [3]
Bone lymphoma may be of relatively low SI on T2-WI due to high cellularity. [6]

PET-CT is helpful to show the enlarged lymph nodes and to show areas of increased metabolic activity that are not easily seen on a regular CT.

Biopsy is needed because definitive diagnosis is difficult when using imaging only.

Primary bone marrow diffuse large B-cell lymphoma is associated with poor prognosis but potentially curable with aggressive treatment, including rituximab-based therapies and stem cell transplantation. [4]

The overall 5-year survival rate is better than for most other primary osseous malignancies. For this reason, recognition of lymphoma as a possible cause for the described radiologic findings is important. [1, 5]

Differential Diagnosis List

Final Diagnosis

Multifocal large B-cell bone lymphoma

URL:	https://www.eurorad.org/case/12522
DOI:	10.1594/EURORAD/CASE.12522
ISSN:	1563-4086