Discussion
Lymphomas are malignant tumors arising from lymphoid tissue. It can be
Hodgkin’s or non-Hodgkin’s type, later being more common, and their
primary epidural occurrence is very rare.4 Out of all
the primary central nervous system (CNS) tumors (which also includes
spinal lymphomas), primary DLBCL of the CNS constitutes only 0.5%
cases, occurring in approximately 2 cases per 10 million people. Spinal
cord location is particularly rare.6
The pathogenesis of primary central nervous system lymphomas (PCNSLs)
has been a matter of considerable debate among experts. Some authors
mention that PCNSL arise de novo in nervous system tissues due to the
presence of lymphoid precursor cells in this
location.7,8 Others argue that tumors from local and
distant sites spread in the epidural space resulting in their apparent
primary presentation.9 The remaining, believe that an
unrecognized preexisting retroperitoneal disease may exist before they
present as PSEL.10
There is a male preponderance (69% vs 31%) of PSEL matching exactly
with our case.11 Though the usual age of presentation
is beyond 40 years of age, several cases have been reported in younger
patients. Nambiar et al12 reported a case of primary
thoracic (T5-T10) spinal epidural B-lymphoblastic lymphoma in a
19-year-old male from India. There are very few reported cases of spinal
epidural NHL in younger age groups.13 Our case of a
24-year-old male is another addition to it.
The thoracic spine is the most commonly involved site followed by the
lumbosacral and cervical spine.8 The common occurrence
of PSEL in the thoracic spine can be explained by the rich venous plexus
in this site, greater length of the thoracic spine as compared with
cervical and lumbar, more tolerance for bulky disease in the thorax and
abdomen and the existence of unrecognized preexisting retroperitoneal
disease.10, 14 The usual location of the tumor in
spinal epidural space is usually dorsal.15 Our case
too had a similar finding of lesion present dorsally and located at the
thoracolumbar region.
The onset of symptoms is usually subacute, occurring over a few days to
weeks. The symptoms and signs of the disease depend on the location and
size of the tumor. Localized back pain followed by lower limb weakness
is the most common symptom.11 Local back pain,
sometimes accompanied by radicular pain to legs and abdomen can be the
prodromal symptom that can persist for several months to a year. Then,
the phase of rapid neurological deterioration occurs over 2-8 weeks
which is due to spinal cord compression.14 Bladder and
bowel disturbances appear only later in the course.16It may give us the idea of time since the onset of the pathology. The
presenting features in our case were back pain radiating to bilateral
lower limbs for three months followed by neurological deficits for the
last 12 days without bladder involvement.
B symptoms (fever, night sweats, and weight loss) were found to be rare
and none had hepatomegaly or splenomegaly in one of the largest surveys,
which is consistent with our case too. As most of the patients presented
in the earlier stage, B symptoms were probably
absent.11
MRI is the investigation of choice in the preoperative and postoperative
evaluations.10 PSEL appears in MRI as isointense on
T1W image and iso- to hyperintense on T2W image, with marked contrast
enhancement.15 Contrast enhancement with Gadolinium
further helps in the assessment of extraosseous soft tissue components.
This allows a better differentiation of various pathologies (e.g.,
metastatic carcinoma and sarcoma), tumor extent, and bony
involvement.15 Similar features were recognized in our
case too.
The whole-body scan should be performed to identify lungs, pleural,
splenic, gastric, intestinal, pancreatic, and renal involvement. Bone
marrow biopsy from the sternum or iliac crest is required to rule out
lymphoreticular involvement. CBC, LDH, and chest X-ray should be
performed as well. In our case, we could not find any positive reports.
Lumbar puncture is not recommended because it is potentially hazardous
because of the coning phenomenon and it is also of limited diagnostic
value as it shows a non-specific increase in protein levels; neoplastic
cells are rarely found.17,18
Monnard et al11 have recommended surgical
decompression in the form of partial or total removal of the tumor mass
and/or decompressive laminectomy. Doing so relieves the spinal cord
compression and also establishes the correct histological diagnosis.
Surgery is clearly indicated when the diagnosis is not yet
established.1 Emergency decompression is needed only
in cases of acute paresis and/or loss of bowel/bladder
control.16 Functional recovery of patients suffering
spinal cord compression due to PSEL is relatively better than that of
patients with metastatic carcinoma.4
Histopathological examination of the biopsy specimen usually shows
diffuse proliferation of atypical lymphoid cells,8which is similar to our finding. Immunohistochemistry analysis with
positive CD20+, CD10+,
BCL6+, and MUM-1- further supported
our diagnosis of DLBCL (germinal center type).5, 19Positive Ki-67 suggested the aggressiveness of the tumor.
Combined modality treatment including radiotherapy and chemotherapy has
been recommended to be the most efficient treatment because lymphomas
are very chemo- and radiosensitive tumors.11, 18, 20In the largest survey until now, local control of 88% and 5-year
overall survival of 69% have been observed with combined modality
treatment.11 Earlier diagnosis and treatment is
associated with improved functional outcomes. Several authors report
that patients with more aggressive histological tumor types have a
poorer prognosis. Patients of over 40 years of age with aggressive
histological tumors have a poor prognosis.10 Our case
was a 24-year-old male, otherwise healthy, and was diagnosed early and
underwent surgery with significant neurological improvement, which is
the most favorable prognostic indicator of overall
survival.11 He responded well to chemotherapy with
complete neurological recovery.