Teaching Case

A 25-year-old male patient was admitted to the emergency services for evaluation of seizures involving left upper limb and lower limb with secondary generalization. He had dull headache, which gradually increased in severity over the period of last 6 months. On motor examination, he showed weakness of left upper and lower limbs with power of 2 out of 5.

Non-contrast CT (Figures 1 to 4) showed a large intra-axial heterogeneous space occupying lesion (white arrow) involving right cerebral hemispheres, with blood attenuation areas and calcifications. Vasogenic oedema was seen with midline shift toward left side and right sided uncal herniation (black arrow in Figure 3).

T2 and T2FLAIR images (Figures 5 to 8) showed a well-circumscribed intra-axial lesion in right frontal and parietal lobes with vasogenic oedema, measuring 8 centimetres in largest dimension.

The lesion showed internal multiple loculi with T2 hypointense areas and popcorn-like lobulated appearance at multiple places. DWI (Figure 9) and ADC map (Figure 10) showed restricted diffusion and low ADC value.

SWI and filtered phase images (Figures 11 and 12) showed blooming with mixed blood products and calcifications. Axial T1 (Figure 13) and T1FS (Figure 14) images showed T1 hyperintense areas within the lesion, not suppressing on FS. Post-contrast T1 fat-saturated image (Figure 15) showed no lesion enhancement.

Post-operative CT (Figure 16) showed a small post-operative cavity with pneumocephalus and reduction of mass effect.

Background

Cavernoma or cavernous malformations are benign vascular lesions occurring in brain and spinal cord, with sizes ranging from few millimetres to few centimetres. They can undergo growth or involution. They can be sporadic or familial, congenital or acquired [1]. Giant cavernoma term is reserved for cavernoma larger than size of 6 centimetres [2]. Giant cavernoma poses a diagnostic challenge in imaging due to heterogeneous internal contents and mass effect.

Clinical Perspective

Cavernoma are benign vascular lesions composed of thin-walled, blood-filled, endothelial-lined capillary caverns. Supratentorial parenchyma is the most common location [1]. Cavernomas are angiographically occult. Complete surgical removal is for patients with symptomatic lesions associated with recurrent bleeds, seizures, and neurological deficits [1-3]. Familial cavernomas are associated with CCM1, CCM2 and CCM3 genes mutation. Acquired cavernoma can occur after radiotherapy to the brain. Cavernoma can remain silent. The incidence of a first symptomatic haemorrhage is 0.08% per patient per year. The risk of subsequent haemorrhage increases ten times after the first haemorrhage. Internal haemorrhages, increase in size and surrounding vasogenic oedema predispose a cavernoma to become symptomatic. No clear guidelines exist for surgical management of cavernoma. Consensus guidelines recommend surgical management after weighing benefits with risks of the surgery [3].

Imaging Perspective

Cavernomas are the second most common vascular malformation of the brain, followed by developmental venous anomalies, with 0.5–1% incidence in general populus [1], with even lower incidence of giant cavernoma [4,5]. Endothelial lining of the cavernoma forms an abnormal blood–brain barrier and hence allows chronic extravasation of blood products. This event forms the basis of imaging appearance of cavernoma with internal blood degradation products and hemosiderin staining in surrounding parenchyma – with typical rim of blooming. Imaging findings of cavernoma depend upon the composition of the lesion and stage of the blood products contained within the lesion. Common locations of cavernoma are cerebral hemispheres and brainstem.

On CT, cavernoma appears hyperdense due to blood products, calcifications or both. CT has sensitivity of 30–50% to detect intracranial cavernomas [1].

MR is the gold standard of imaging for cavernomas, recommended by Angioma Alliance, with class I evidence. Cavernoma imaging must include gradient echo (GRE) imaging [1,3]. Cavernomas show typical popcorn-like lobulated appearance with variable internal heterogeneous T1 and T2 signals depending upon the age of the blood products within. Surrounding parenchyma may show oedema and hemosiderin staining. Imaging checklist for a radiologist should describe number, locations and dimensions of lesions, mass effect and presence of other associated abnormalities. Cavernoma can be associated with an adjacent developmental venous anomaly (DVA).

Zabramski classification divides cavernoma into 4 types based on size, signal characters on T1 and T2 and morphology.

Outcome

Patient underwent craniotomy with surgical resection. The lesion showed well-circumscribed margins and a capsule. It was resected out en-toto. Internal appearance of the lesion was grape-like clusters filled with altered blood products and clots. Post-operative histopathology showed no components of malignancy. The lesion was confirmed to be a cavernoma.

Take Home Message

Giant cavernoma can mimic intra-axial neoplasms and may pose a diagnostic challenge.