Large Calcified Cystic Cavernous Angioma in the Thalamus

-Case Report-

Kazufumi SATO and Toshihiko KUBOTA

Department of Neurosurgery, Fukui Medical School, Fukui

Abstract

A 52-year-old female presented with an unusual large cystic cavernous angioma with dense calcification in the thalamus manifesting only as headache despite the large mass with surrounding brain edema. Both T, and T2-weighted magnetic resonance images revealed a large cystic mass with an intramural nodule appearing a reticulated, irregular mixed intensity core. The lesion was totally removed through a transcortical-transventricular approach. The postoperative course was uneventful with no signs of neurological deficit or residual mass 5 years later.

Key words: cavernous angioma, cyst, calcification, thalamus, computed tomography,

magnetic resonance imaging

Received May 11, 1994; Accepted June 30, 1994

Introduction

Cavernous angioma is a relatively rare vascular malformation in the central nervous system. Recently, cavernous angioma has been found more often by computed tomography (CT)",", 12,15,16) and/or

magnetic resonance (MR) imaging."`,") Cavernous angioma frequently contains small cysts and/or tiny calcifications.') We describe a patient with a cavernous angioma in the thalamic region containing a large cyst and dense calcification.

Case Report

A 52-year-old female presented with a 2-year history of intermittent occipitalgia. Neurological examination on admission was normal. Plain x-ray films showed an abnormal calcification. Precontrast CT revealed a mass with a diameter of approximately 5 cm in the right thalamic region containing a large cyst with irregular-shaped dense calcification (Fig. 1 upper). Postcontrast CT showed the slightly enhanced cyst wall. MR imaging demonstrated a large low-intensity (but higher than cerebrospinal fluid intensity) mass containing an irregular mixed intensity

area on the T,-weighted images (Fig. 1 middle). The T2-weighted MR images revealed a high-intensity le

sion with surrounding brain edema and a reticulated, irregular mixed intensity core (Fig. 1 lower).

The lesion was totally removed by a transcortical

transventricular approach through a right temporo

parieto-occipital craniotomy. The large cyst contained xanthochromic fluid.

Histological examination found the lesion containing of a network of vascular channels. The vessel walls usually showed collagenous thickening, and thrombosed vessels were frequently seen. Roundish calcified bodies were closely related to the thrombosed vessels. Linear calcification on the walls of non-thrombosed vessels was occasionally observed

(Fig. 2 upper). Numerous calcified bodies were present in the surrounding gliosis (Fig. 2 middle). The cyst wall consisted of fibrous tissue containing neocapillaries with proliferation of inflammatory cells and hemosiderin deposits (Fig. 2 lower). The histological diagnosis was cavernous angioma.

The postoperative course was uneventful. Followup examination 5 years later found no neurological deficit and MR imaging revealed no residual mass

(Fig. 3).

Discussion

Intracranial vascular hamartomas are classified into four groups based on histological features: 1) capillary telangiectasis, 2) cavernous angioma, 3) arteriovenous malformation, and 4) venous malformation. Cavernous angioma is a well-defined lesion consisting of sinusoidal vascular channels lined by a single layer of endothelial cells. The walls of the vessels consist of collagen fibers, and have no mus

cle nor elastic fiber. The surrounding stroma shows fibroblastic proliferation without intervening

neural tissue. The histological differentiation be

tween cavernous angioma and capillary telangiectasis

is sometimes difficult, ia,2o) and the association of

these lesions has been reported.') The histological ap

pearance of our case was compatible with cavernous angioma, but the vessel walls were usually thick and

thrombosed vessels were frequent.

Fig. 1 upper: Precontrast CT scans showing a large cystic mass with dense calcification in the right thalamic region. middle: Axial T,-weighted MR images (spin echo [SE] 350/35 msec) showing a large low-intensity mass with irregular mixed intensity. lower: Axial T2-weighted MR images (SE 2000/50 msec) showing the lesion as a large high-intensity mass with a reticulated core of irregular mixed intensity.

Fig. 2 upper: Photomicrograph showing network of vascular channels with roundish calcified bodies (arrows) and linear calcification on the vessel walls (arrowheads). Hematoxylin and eosin (HE) stain, x 75. middle: Photo

micrograph showing numerous calcified bodies in the gliosis. HE stain, x 75. lower: Photomicrograph of the cyst wall showing fibrous tissue containing neocapillaries and prolifera

tion of inflammatory cells. HE stain, x 170.

The cerebral hemisphere is the most common site for intracranial cavernous angioma.a,",20I The

posterior fossa, basal ganglia, or ventricular wall are

less frequently affected, and the thalamus is seldom involved. 9,12,191 The most common clinical symptom

of cavernous angioma is seizures,',',' 1,15-18,20) and others include headaches, intracranial bleeding, or focal neurological deficits. Our patient only manifested headache despite the large lesion associated with surrounding brain edema.

Cavernous angioma with a large cyst is unusual, 3,6,7,1',19) compared to the association of small cysts. Although the etiology of cyst formation is not established, cyst growth may be the result of recurrent hemorrhage from sinusoids of the vascular malformation or from the neocapillaries of the cyst wall. The cyst membrane is histologically similar to the outer membrane of chronic subdural hematoma. Our histological findings also support the relationship between repeated minor bleeding and the formation of a large cyst.

Calcifications in cavernous angioma are visualized by plain x-ray films in 11-40% of cases. 4,13,20) Calcification nests occur particularly within thrombosed luminae,l,a,13,14) or intervascular spaces.4) In our case, three types of calcification nest were noted: 1) roundish calcification closely related to the thrombosed vessels, 2) linear calcification on the wall of non-thrombosed vessels, and 3) roundish calcified

bodies in the gliosis. These calcifications are considered to be dystrophic calcification occurring under

pathological conditions such as calcified tumors or aortic media.21

The neuroimaging appearance of cavernous an

gioma is well known. CT shows these lesions as a well-defined hyperdense mass with mild postcontrast enhancement. The finding of calcification is sug

gestive of cavernous hemangioma,1,8,12,15,16) but is nonspecific and indistinguishable from calcifications

seen in other intracranial lesions."') The CT ap

pearance of our case was unusual for cavernous angioma, so the differential diagnosis from other

cystic lesions such as astrocytoma, oligodendro

glioma, meningioma, or parasitic cyst was difficult. The characteristic MR imaging appearance of cav

ernous angioma is a reticulated mixed intensity

core with a surrounding low-intensity rim especial

ly on the T2-weighted images. 11-12,18) The mixed in

tensity area is due to varying blood flow within the lesion, thrombosis, recanalization, calcification,

and intralesional hemosiderin.18) Other MR imaging

patterns include focal hyperintense, focal inhomo

geneous hyperintense, and multifocal isointense centers. 18) In our case, the intramural nodule appeared

as a mixed intensity area on both T1 and T2

weighted images. MR imaging is the most sensitive

diagnostic method for cavernous angioma even

with a large cyst and dense calcification.

Intracerebral cavernous hemangioma can usually

be treated by surgery, regardless of size or preop

erative symptoms. Surgery is indicated to avoid the risk of subsequent bleeding or rapid growth of the

cyst.4,9,17,20) In most patients, surgical removal is easy and the outcome of total removal is excel

lent.a,is,2o1

Fig. 3 Axial T1-weighted MR image (SE 500/38 msec) 5 years after the operation showing no residual mass, and only operation scars in the right thalamus and cerebral cortex.

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Address reprint requests to: K. Sato, M.D., Department

of Neurosurgery, Fukui Medical School, 23

Shimoaizuki, Matsuoka-cho, Yoshida-gun, Fukui

910-11, Japan.