Discussion
EHE is a rare low grade malignant neoplasm with potential for
metastasis. Only 20% of the cases present with
metastasis1.,5. It originates from vascular
endothelial or pre-endothelial cells. Although it can develop anywhere
in the body it most reported in the liver, lungs and bone. Primary EHE
of the bone is rare constituting only 1% of all malignant tumours of
the bone1,2,5., as such primary involvement of the
spine in EHE is very rare 5. Spinal EHE has a
non-specific clinical presentation, usually with pain (mostly radicular
or mechanical in nature) or neurological deficits attributable to
compression of the spinal cord and/or nerve roots. There is a paucity of
literature on EHE in Africa with only a few case reports on pulmonary,
hepatic and pleural EHE and none for primary EHE of the
Spine6,7. It occurs equally in both males and females
with no racial predilection1.Weissferdt et al
describes better overall survival for unicentric tumour as compared to
multifocal disease (89% and 50% respectively) and a mortality rate of
20%. The median survival is at 1.3 years and 5-year survival of 33%
after disease progression5.
Although EHE of the spine has no pathognomic features that are specific
enough to be used as the sole means of diagnosis, most if not all cases
show an expansile osteolysis with bony trabeculae and lack a sclerotic
margin. There is usually vertebral body collapse with segmental kyphotic
deformity1,2,3,4,5. On MRI the lesions are usually
isointense to grey mater on T1 weighted imaging, slightly hyperintense
on T2 weighted imaging with increased uptake of contrast on contrasted
sequences1. Chen P et al., suggests that18F-FDG PET/CT scan may be of some use in difficult
cases (especially those with multifocal disease) with hypermetabolism,
but this is not pathognomic and as such cannot be used in solitude to
confirm diagnosis of EHE or its dissemination2.
Macroscopically the tumour a reddish-brown mass with tendency to bleed.
The diagnosis of EHE rests mostly on the histopathological analysis.
Microscopically the tumour cells appear as round, polygonal or fusiform
with a central nucleus and intracytoplasmic vacuolations but with the
absence of increased mitotic activity or
necrosis2,3,4,5,8. Immunohistochemically EHE stains
positive for CD31, CD34, EGR, Factor VIII related antigen and FLI-12,3,4,5,8. Cytogenetic analysis can be used to show
chromosomal translocation involving chromosomes 1 [t(1;3) and 3
(p36.3;q25) that results in WWTRI-CAMTAI fusion. This is present in
approximately 90% of the cases with EHE2,3. A subset
of patients with EHE may show YAP-1 TFE 3 fusion10.
The mainstay of treatment for patients with EHE of the spine seems to be
multimodal with surgery, total resection where feasible, as the
centrepiece.2,3,5 Pre-operative embolization to reduce
the vascularity of the tumour and radiation and chemotherapy are also
described. Given the rarity of EHE, especially EHE of the spine, there
currently exists no universally accepted treatment guidelines with
clearly defined outcomes.