Giant Cavernomas: Gigantic Propositions for a Lilliputian Problem?
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.310114
Source of Support: None, Conflict of Interest: None
Keywords: Cavernoma, cavernous angioma, giant cavernoma, vascular malformation
Cavernomas are normally found in the brain parenchyma, basal ganglia and deep cerebral white matter as well as in intraventricular locations. They are composed of sinusoidal vascular channels without intervening parenchyma. Reports of giant cavernomas are rare and microsurgical excision is the treatment of choice in symptomatic patients. Lawton et al. defined giant cavernomas to be those with a size of more than 6 cm. On the other hand, Ozgen et al. defined them as being more than 4 cm. We present additional two cases of giant cavernomas of more than 6 cm size each.
A 13-year-old male presented with habitual seizures since one year of age. Seizures were characterized by a confused state along with lower limb jerks. He had an average scholastic performance with normal higher mental function and neurologic examination. Computerised tomography (CT) brain revealed a large hyperintense circumscribed lesion in the left temporo-parietal region [Figure 1]a Magnetic resonance imaging (MRI) brain was suggestive of a 70 mm x 60 mm x 55 mm T1 and T2- weighted heterogenous, hyperintense and circumscribed left temporo-parietal lesion [Figure 1]b and [Figure 1]c. In addition, another small lesion of 1 cm was seen in the left temporal region suggestive of multiplicity. Digital subtraction angiography (DSA) showed no evidence of any underlying venous or arterial channels. We opted for a parieto-occipital craniotomy and a translesional approach was taken at the point where the cavernoma was surfacing. The lesion was excised in toto with careful dissection around the gliotic capsule. The gross specimen had a firm consistency with a reddish-purple, multicystic appearance [Figure 2]. Post operatively, the patient developed transient hemiparesis which improved within the next 24 hours with post-operative scan showing complete resection [Figure 1]d.
A 26-year-old male presented with generalized seizures for ten years along with bilateral visual impairment for the last two years. Examination revealed right sided weakness with perception to light present in both eyes. CT brain showed a 99 mm x 94 mm x 63 mm left sided trigonal lesion. MRI brain T2–weighted imaging showed a solid-cystic intraventricular lesion which was heterogeneously contrast enhancing, involving the temporal horn, body and trigone of the left lateral ventricle resulting in its dilatation. Gradient recalled echo (GRE) images were suggestive of blooming and calcification along the anteromedial aspect and a cystic component along the posterolateral aspect of the lesion [Figure 3]. Left fronto-temporo-parietal craniotomy was performed and a transparietal, tranventricular route was used for gross total excision. There was no improvement in vision, but the patient was seizure free till the last follow-up. Histopathology of both cases was suggestive of cavernoma with blood filled vascular spaces, hyalinized wall and focal calcification. The intervening parenchyma showed gliosis along with haemosiderin pigment [Figure 4].
These two cases illustrate the variable presentation of a common lesion presenting in voluminous sizes. Cavernomas commonly pose as vascular mimickers of arteriovenous malformations, venous angiomas, high grade glial neoplasms or hemorrhagic tumours. Giant cavernomas themselves may be associated with aberrant venous drainage or increased vascularity making their excision more difficult. The need to remove these lesions in toto puts an additional risk of retraction on normal brain tissue.
Is a sub group of “Giant Cavernomas” needed?
The natural incidence of cavernomas ranges between 0.4 -0.5%. The incidence of giant cavernomas is rare and to date 22 cases have been reported including this study [Table 1].
Generally, most cavernomas are around 0.5 to 46 cm3 in volume with an average of 1.4 cm3. A review of literature revealed giant cavernomas to be 7.2 cm in size on an average with a female preponderance (1.7:1). The reasons for attaining such large sizes in parenchymal cavernomas may be due to thrombosis, engorgement, recurrent bleeding episodes, pseudo-capsule formation, new vessel recruitment, osmotic engorgement and hormonal influence. However, reports suggest that growth can be present without any evidence of such features. Intraventricular cavernomas on the other hand, tend to attain larger sizes due to the relative minimal resistance offered in the ventricular compartment and tend to produce mass effect as was seen in our second case. Multiplicity is observed in 30% of sporadic and in 84% of familial cases. Although rare in giant cavernous malformation, multiplicity was observed in case 1 in our series but there was no history of familial inheritance.
Location wise, giant cavernomas can be parenchymal, periventricular or intraventricular. In children, there is increased tendency for normal sized cavernomas to occur in the periventricular locations. Ozsoy et al. reported a majority of giant cavernomas in the periventricular areas as well. The presenting complaint of giant cavernomas is most commonly seizures followed by mass effect, progressive neurological deficit, increased head circumference, field defects and haemorrhage [Table 1]. Both the cases in our series presented with seizures, while one had visual impairment likely related to mass effect.
Considering the distinct features of giant cavernomas including their propensity towards bleeding and hemiparesis, they present as a unique challenge and do warrant a separate classification. Nonetheless, the approach towards both giant and normal sized cavernomas along with basic radiological similarities is based on the same principal of complete resection whenever possible.
Imaging: Giant cavernomas differ from normal sized cavernomas radiologically in terms of their size and their propensity to occur in children. Giant cavernous malformations are commonly misinterpreted as neoplasms or other vascular malformations due to atypical imaging features. The radiology of giant cavernomas is similar to that of parenchymal ones. Larger lesions may show high variability with mild or no contrast enhancement to significant contrast enhancement. MRI imaging in cavernomas show iso to hyper signal intensities in T1. A peripheral rim i.e., a T2 hypo intense rims due to the paramagnetic effect of hemosiderin may also be seen. Also, hematomas in different maturation stages may be seen in T2-weighted and gradient echo images leading to an appearance of a circumscribed, heterogenous mass. Gradient echo T2-weighted MRI sequences are most commonly used for detecting smaller lesions due to their sensitivity to the artifacts induced by hemosiderin and thus are necessary to screen for multiple lesions. Giant cavernomas may have more incidence of cystic component than normal cavernomas as was seen in our cases.
Histopathology: Giant cavernomas share similar features to normal sized cavernomas in terms of histopathological presentation. They are made up of variable sized vascular channels (resembling caverns) without the presence of muscular or elastic fibers within a collagenous tissue matrix and without the presence of any neuronal or tumour elements. There may be the presence of associated reactive gliosis and hemosiderin deposition in the surrounding parenchyma. Also, non-specific features like thrombosis, old and new hemorrhages, or calcification may be present.
Treatment: The proclivity of giant cavernomas towards mass effect and raised intracranial pressure (ICP) as well as rebleed warrants early intervention. Other indications for intervention include symptoms such as neurologic deterioration and intractable epilepsy. Complete removal of cavernoma is necessary using the right approach., The question remains whether to remove the lesion piecemeal or en masse with respect to giant cavernomas. In our first case, complete en masse removal resulted in transient weakness which improved. Piecemeal removal carries the risk of subtotal excision. The type of resection for giant cavernomas should be evaluated with regards to their proximity to eloquent areas and venous anomalies in order to prevent venous infarctions. The transcortical approaches can be used for lateral ventricular cavernomas especially trigonal cavernomas as was seen in case two. In the case of parenchymal giant cavernomas, the shortest trajectory may be utilized as an approach. A majority of cases in review [Table 1] showed improvement after surgery validating complete resection.
Microsurgical excision remains the treatment of choice for giant cavernomas. In toto excision may be advocated depending on the location with respect to eloquence and venous anatomy. Complete resection is associated with a good prognosis.
The authors would like to thank Dr. Rajalakshmi P, Assistant Professor, Pathology Department, Sree Chitra Tirunal Institute for Medical Sciences and Technology for her contribution towards the paper.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]