Keywords
cavernous malformation - de novo formation - hemorrhage - regression - spine
Introduction
Cavernous malformations within the spinal canal are rare vascular malformations, significantly
less common than their intracranial counterparts. Due to their rarity, the natural
course of spinal cavernous malformations remains poorly understood.[1] While spontaneous regression has been rarely reported in intracranial cavernous
malformations, no such cases have been documented in de novo spinal lesions, making
their natural history particularly enigmatic.
Symptoms often arise when the malformation causes bleeding or exerts pressure on surrounding
spinal cord tissue, leading to pain, sensory disturbances, or motor deficits.[2] Surgical intervention is generally recommended, when the lesion becomes symptomatic
after hemorrhage, primarily to prevent rebleeding and worsening neurological deficits.[3] However, both the optimal timing and surgical approach remain subjects of ongoing
debate,[4] especially in anteriorly located spinal lesions, where technical difficulty and
the risk of postoperative deficits are considerably higher. In such cases, even more
meticulous clinical judgment is required to determine the most appropriate management
strategy.
In this report, we present a highly unusual case of a de novo cavernous malformation
in the cervical spine that demonstrated spontaneous regression following an initial
hemorrhagic event. Prior imaging showed no abnormalities at the lesion site, confirming
its classification as de novo formation. Although histopathological confirmation was
not available, the imaging findings and clinical presentation strongly suggested a
cavernous malformation. This case provides valuable insight into the natural behavior
of spinal cavernous malformations and raises important considerations regarding surgical
decision-making, particularly in cases where spontaneous regression may be possible.
Case Description
A 74-year-old male was referred to our hospital with neck pain following an episode
of head trauma. Upon examination, he exhibited no neurological deficits. His medical
history was negative for prior radiation exposure, genetic predisposition to vascular
malformations, or previous spinal lesions. Given the presence of isolated neck pain
and no neurological symptoms, an initial computed tomography scan was performed, revealing
a hyperdense lesion on the left side of the spinal canal at the C2 level ([Fig. 1]). This finding prompted further investigation with magnetic resonance imaging (MRI)
to characterize the lesion.
Fig. 1 Computed tomogram at onset showing a hyperdense lesion (arrow) on the left side of
the spinal canal at the C2 level.
MRI revealed a 16 × 9 × 20 mm intradural, extramedullary mass at the C2 level, along
with a smaller adjacent 7-mm intramedullary nodule ([Fig. 2]). The lesion exhibited heterogeneous signal intensity on T2-weighted imaging, consistent
with hemorrhagic cavernous malformations, and was associated with significant spinal
cord edema. On T1-weighted imaging, the lesion appeared mostly isointense, and gadolinium-enhanced
imaging showed almost no contrast enhancement. Given that MRI performed 1 year earlier
for an unrelated condition showed no abnormalities at this site ([Fig. 3]), the lesion was classified as a de novo formation. These imaging findings strongly
suggested a cavernous malformation with a recent hemorrhage.
Fig. 2 Magnetic resonance (MR) images at onset. T1-weighted (left) and T2-weighted (center)
MR images showing a 16 × 9 × 20 mm intradural, extramedullary mass at the C2 level,
along with a smaller adjacent 7-mm intramedullary nodule (right). The lesion exhibits
nearly isointense signal intensity on T1-weighted image and heterogeneous signal intensity
with a hemosiderin rim on T2-weighted image, consistent with a hemorrhagic cavernous
malformation. The axial T2-weighted image (left) also showing intramedullary high-intensity
suggestive of edema.
Fig. 3 A T2-weighted magnetic resonance (MR) image taken approximately 1 year before the
onset of the disease (left) and a T2-weighted MR image taken at the time of onset
of the disease (right). There is no abnormality in the same area, suggesting de novo
formation.
Due to the lesion's size, hemorrhagic features, and the potential risk of rebleeding
leading to neurological deterioration, surgical excision was initially planned. However,
while awaiting surgery, the patient's neck pain resolved sooner than expected. Follow-up
MRI conducted 9 days later during preoperative evaluation revealed significant regression
of the intradural hematoma, reduction of spinal cord edema, and partial shrinkage
of the lesion itself ([Fig. 4]). Given this unexpected improvement, the surgical plan was reconsidered, and a decision
was made to opt for conservative management instead. Over the subsequent 5 years,
serial MRIs showed a continuous decrease in the size of the cavernous malformation
([Fig. 4]), with complete resolution of the hematoma and no further bleeding events. The patient
remained entirely symptom-free throughout this period [Fig. 5].
Fig. 4 T2*-weighted images showing the regression of hematoma and intramedullary nodule.
At onset (left), 9 days after onset (center), and 5 years after onset (right). By
day 9, the hematoma and edema have significantly regressed, and the intramedullary
nodule reduced in size; at 5 years, the intramedullary lesion remains stable with
no recurrence.
Discussion
The present case provides unique insights into both the de novo formation and the
spontaneous regression of cavernous malformations in the spinal canal. To our knowledge,
no previous reports have documented the spontaneous regression of de novo spinal cavernous
malformation, making this case a unique contribution to literature. While cavernous
malformations more commonly develop in the intracranial compartment,[1] their occurrence in the spinal canal remains rare, and their natural history is
poorly understood due to the frequent need for surgical intervention.[5] Spontaneous regression of cavernous malformations has been reported in 55% of intracranial
cases,[6] which is likely the result of hemorrhage resolution.[6] Similarly, spontaneous regression has been observed in other intracranial vascular
malformations, such as capillary hemangiomas and arteriovenous malformations, potentially
due to thrombotic occlusion or inflammatory processes.[7]
[8] In contrast, regression in spinal cavernous malformations, particularly de novo
lesions, has not been previously reported, highlighting the uniqueness of this case.
This case, in which a cavernous malformation developed spontaneously without known
predisposing factors such as prior radiation therapy[9] or genetic predisposition,[10] and then regressed following hemorrhage, challenges conventional assumptions about
the behavior of these vascular lesions. The de novo formation, occurring without radiation
exposure or familial predisposition, further suggests potential roles for localized
genetic mutations, dysregulation of angiogenic factors, or microenvironmental changes
within the spinal cord as Retta and Glading stated in their study of cerebral cavernous
malformation.[11]
The spontaneous regression observed in this case may involve several mechanisms, as
seen in intracranial cavernous malformations. Hematoma resorption, well documented
in cerebral lesions, likely reduced internal pressure within the malformation, facilitating
its collapse.[6] Furthermore, mechanisms such as thrombotic occlusion of vascular lumens,[12] proximity of the lesion to the cerebrospinal fluid (CSF) space,[13] and age-related vascular fragility, may explain the sustained regression observed
over 5 years. This theory is supported by the initial MRI findings, which suggested
an acute hemorrhagic component, and a follow-up imaging, which showed a significant
decrease in hematoma volume, surrounding edema, and lesion size. Regarding thrombotic
occlusion within the vascular channels of the malformation, intralesional thrombosis
has been documented in cerebral cavernous malformations[12] and could similarly contribute to lesion shrinkage in spinal cases. The formation
of thrombi within the vascular spaces may restrict blood flow, leading to the gradual
involution of the lesion. Additionally, advanced age may influence this process, as
reduced vascular elasticity and compliance could facilitate passive collapse of the
cavernous structure over time. Furthermore, the lesion's proximity to the CSF space
could have played a role in its regression. The presence of CSF might assist in the
transport and absorption of cellular debris from the collapsed cavernous malformation,[13] accelerating lesion reduction. This could represent a unique form of lesion regression
more likely to occur in cavernous malformations exposed to the CSF space. The present
case expands this limited body of evidence and underscores the need to further investigate
factors predisposing to both de novo formation and spontaneous regression, which may
ultimately refine decision-making between surgical and conservative approaches.
The decision to perform surgery for spinal cavernous malformations requires an individualized
approach, balancing the risks of intervention against the potential for spontaneous
regression. Surgery, particularly for anteriorly located lesions, carries a significant
risk of neurological deterioration, especially in patients with mild symptoms. While
early surgical intervention may prevent rebleeding and further neurological deficits,
it also precludes observation of the lesion's natural course. The unexpected regression
seen in some cases suggests that close monitoring may be a viable alternative in selected
patients. To optimize management, clear criteria are needed to determine when observation
should transition to surgery. Regular neurological assessments and imaging follow-up
are essential for detecting early signs of progression. If any deterioration occurs,
prompt surgical intervention is warranted to prevent permanent deficits. In light
of this case, clinicians should consider close observation with serial imaging in
asymptomatic or minimally symptomatic patients with spinal cavernous malformations,
particularly when early regression is observed, as this strategy may help avoid unnecessary
surgery in select cases.
There are several differential diagnoses for intradural masses, including nerve root
hemangioblastoma, which shares certain radiological features with cavernous malformation.[14] However, careful evaluation of imaging findings—such as the presence or absence
of cyst formation, enhancement patterns, evidence of hemorrhage, hemosiderin rim,
and flow voids—can aid in differentiation.[15]
[16] Accurate preoperative diagnosis is essential to avoid unnecessary surgical intervention
and to guide appropriate management. In our case, although histopathological confirmation
was not obtained, and other diagnoses such as hemorrhagic neoplasms cannot be entirely
excluded, the diagnosis was strongly supported by characteristic MRI features—including
a hemorrhagic intradural extramedullary mass with a hemosiderin rim and lack of flow
voids or cystic components—and its stable involution over 5 years. This extended follow-up
period, while reinforcing diagnostic confidence, remains a limitation for drawing
definitive conclusions about the long-term prognosis. Therefore, while delayed recurrence
or complications are rare, extended surveillance should be considered in similar cases
to monitor for any late-onset issues. This limitation must be acknowledged when interpreting
our findings.
Conclusion
This case highlights the rare phenomenon of spontaneous regression in de novo spinal
cavernous malformation. While these lesions are typically treated surgically due to
the risk of neurological decline, our findings suggest that some may regress without
intervention. Possible mechanisms include hematoma resorption, vascular collapse,
thrombosis, or interaction with CSF. Although based on imaging findings alone and
lacking histopathological confirmation, the diagnosis was supported by characteristic
radiological features and stable involution over 5 years. The case also emphasizes
that de novo formation and spontaneous regression may share underlying biological
pathways related to vascular instability and remodeling. Given the uncertain long-term
natural history and the possibility of late recurrence, extended follow-up is warranted.
Conservative management with close imaging surveillance may be appropriate in select
minimally symptomatic patients, particularly when early regression is documented.
Fig. 5 Timeline showing changes in symptoms and the size of the hematoma and lesion. At
symptom onset, both the hematoma and lesion were at their largest. Over time, a gradual
reduction in size was observed. Five years after onset, the lesion has remained stable
without any signs of enlargement.
