Primary spinal epidural lymphoma mimicking lumbar spinal stenosis

A 60-year-old woman was sent by the orthopedic surgeon to study the lumbar spine with suspicion of acquired lumbar spinal stenosis. The patient referred lumbar pain irradiating to the buttocks and both lower limbs, without radiculalgia or neurological symptoms, during the last eight months.

Sagittal T1 and T2 fat suppression-weighted images show low signal in the L1, L3 and L4 vertebral bodies. There are soft tissue masses in the perivertebral and epidural spaces. The epidural soft tissue component is responsible for severe cauda equina compression and produces a polygonal appearance of the dural sac. This appearance reflects tethering by the meningovertebral ligament (Hoffmann), lateral and dorsal additional ligaments, which connect the dura mater to the osteofibrous walls of the spinal canal. The soft tissue component enhances after gadolinium injection. Despite signal abnormality on marrow of the vertebral bodies, and adjacent epidural components, there is no cortical destruction. Extravertebral soft tissue component surrounds the L3 vertebral body without cortical disruption – wraparound sign.
Diffusion-weighted images show marked restriction not only in the soft tissue component, but also on marrow of involved vertebral bodies.
Biopsies of the perivertebral soft tissue component and the L3 vertebral body were performed.

Primary spinal epidural lymphoma (PSEL) is a subset of lymphoma where, at the time of diagnosis, there are no other recognisable sites of lymphoma involvement, after a complete negative diagnostic work-up [1]. It represents about 0.1 - 6.5% of all lymphomas.
Most of these patients present in their fifth, sixth or seventh decades of life [2].
Symptoms and signs are similar to any other epidural tumour: back pain, upper or lower limbs weakness, bladder or bowel dysfunction, usually with sub-acute course, over days to weeks.
To our knowledge, only one case of PSEL with clinical presentation of lumbar spinal stenosis has been described, by Travlos et al. [3].
Back pain is present at the level of the epidural tumour, depending on tumour location, and extension.
Plain radiography and CT rarely provide useful information. On MRI, PSEL presents with an iso-intense signal on T1-weighted images and an iso-to hyper-intense signal on T2-images, with a homogeneous contrast enhancement of bone marrow and soft tissue component. As we show in our case, there is marked restriction on DWI. In lymphomas, cells can infiltrate between bone trabeculae, extending through small penetrating channels into the soft tissue, which explains no cortical disruption and the wraparound sign.
The infiltrative growth through the foramen is typical of lymphoma. Para-vertebral extension is better appreciated on T1-weighted images after gadolinium administration, and especially in DWI-weighted images, as seen in our case.
Regarding differential diagnosis and in contrast with PSEL, multiple myeloma, osteomyelitis, metastases replace bone marrow and involve adjacent soft tissue through cortical bone destruction. Epidural abscess, centred on and in continuity with the diseased disc, adjacent to vertebral bodies, has a fusiform appearance. Spinal epidural haematoma gives high signal on both T1 and T2-weighed images [5].
Histologically, most PSEL are B-cell type lymphomas of intermediate or high grades. It can be Hodgkin or non-Hodgkin, the latter being much more common. The Hodgkin-type has been reported in both adults and paediatric populations [6].