Neurol Med Chir (Tokyo) 43, 439¿442, 2003

Serial Neuroimaging of Encapsulated Chronic
Intracerebral Hematoma With Repeated Hemorrhage
—Case Report—
Wataro TSURUTA, Koji TSUBOI, and Tadao NOSE
Department of Neurological Surgery, Institute of Clinical Medicine,
University of Tsukuba, Tsukuba, Ibaraki

Abstract
A 69-year-old woman presented with headache and short memory disturbance. Computed tomography
(CT) demonstrated a small cystic mass lesion in the left temporal lobe. CT and magnetic resonance
imaging showed that this lesion enlarged with repeated hemorrhages, associated with progressive
amnesia and headache during 3 years follow up. Surgery demonstrated a well-demarcated hard mass
lesion in the medial temporal lobe through a transcortical approach after opening left sylvian fissure.
The lesion was located entirely in the brain parenchyma and was removed en-bloc after cutting some
capillary-like vessels on the capsule. The histological diagnosis was encapsulated old hematoma. The
histological findings suggested that expansion of the lesion was due to multiple bleedings from the
sinusoidal vessels in the capsule fed by small feeding arteries. The mass effect due to the expansion of
the encapsulated hematoma caused progressive short-term amnesia and headache, which were
completely resolved by the surgical removal.
Key words:

encapsulated hematoma,

intracerebral hematoma

Introduction

(Figs. 1A center and 2 left). Cerebral angiography
demonstrated no vascular abnormality (data not
shown). Her headache became severe and short
memory disturbance appeared in 1998. CT and MR
imaging revealed expansion of the lesion by a fresh
clot (Figs. 1A right and 2 right), prompting the decision to perform surgical removal. The preoperative
differential diagnosis included benign cystic tumor
and cavernous hemangioma with cystic formation.
The left sylvian fissure was opened following frontotemporal craniotomy. The lesion was entirely
situated in the brain parenchyma. The well-demarcated hard mass lesion was found and removed
en-bloc through a medial temporal transcortical
approach. No obvious abnormal vessels were observed in the vicinity of the lesion except for several
capillary-like vessels in contact with the capsule.
The contents of the capsule were old clots with a
muddy appearance (Fig. 3A).
Histological examination revealed that this capsule consisted of outer and inner layers. Lymphocytic infiltration and sinusoidal vessels were observed
in the outer layer, whereas the inner layer contained
degenerative sinusoidal vessels and hemosiderinladen macrophages in proliferating fibroblasts

Encapsulated chronic intracerebral hematoma
(ECIH) is a very rare entity first reported in 197821)
and 1981.5) The precise etiology of this condition
remains to be clarified. We recently encountered a
case of ECIH, which we were able to follow for over
3 years before surgical removal. Here we describe
the serial changes on neuroimaging and the histological observations of the removed specimen.

Case Report
A 69-year-old woman presented with complaints of
headache. Computed tomography (CT) detected a
low-density cystic lesion with thin ring-like enhancement in the left temporal lobe in 1995 (Fig. 1A
left, B). Neurological examination demonstrated no
abnormality except for intermittent headache,
which lasted approximately 30 minutes. Follow-up
CT and magnetic resonance (MR) imaging revealed
a small amount of hemorrhage in the cyst in 1996
Received
2003

November 29, 2002;

Accepted

April 1,

439

W. Tsuruta et al.

440

"

Fig. 1

Fig. 2

T2-weighted magnetic resonance images
taken one year after initial admission (left)
demonstrating an old hematoma containing
a small amount of fresh hemorrhage in the
left temporal lobe, and 2 years later (right)
showing the lesion is filled with low-intensity fresh clot.

(Fig. 3B).
Her postoperative course was uneventful, and her
headaches and memory disturbance were completely resolved. There has been no recurrence after 4
years of follow up.

Discussion
Small spontaneous intracerebral hematomas are
usually totally absorbed, but on rare occasions the
hematoma may become encapsulated and expand
over a long period with repeated internal bleeding,
as seen in this case. CT and MR imaging clearly
demonstrated the repeated bleeding and expansion

Fig. 3

A: Computed tomography
scans at initial examination
(left) revealing a low-density
cystic mass lesion in the left
temporal lobe, one year later
(center) showing the cystic
lesion had enlarged and
contained a fluid level due to a
small hemorrhage, and 2 years
later (right) demonstrating
expansion of the cyst by fresh
hemorrhage. B:
Computed
tomography scan with contrast medium at initial examination revealing thin ring-like
enhancement of the lesion.

A: Photograph showing the hematoma encapsulated by hard connective tissue, which
contained old clots with a muddy appearance. B: Photomicrograph of the capsule
demonstrating that the capsule consists of
outer and inner layers. Lymphocytic infiltration and sinusoidal vessels are present
in the outer layer, whereas the inner layer
contains degenerative sinusoidal vessels
and hemosiderin-laden macrophages in
proliferating fibroblasts. HE stain, ×200.

of the lesion during 3 years. Thirty cases of ECIH
with histological evidence have been reported
(Table 1).1,3–8,11–17,19) The mean age was 41.8 years
old and the most frequent symptoms were headache and seizure. The male to female ratio is two to
one, and the most frequent locations were the frontal, temporal, and parietal lobes. Most reported
cases of ECIH were followed up for less than several
months before surgery, and only two cases including ours demonstrated expansion of the lesion with

Neurol Med Chir (Tokyo) 43, September, 2003

Encapsulated Hematoma
Table 1
Case
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

441

Clinical characteristics of the patients
Author (Year)

Hirsh et al. (1981)5)
Takahashi et al. (1983)17)
Aoki and Mizuguchi (1984)1)
Lin et al. (1984)6)

Terada et al. (1985)19)
Masuzawa et al. (1985)7)
Pozzati et al. (1986)12)

Chan and Tse (1987)3)
Steiger et al. (1987)15)
Fiumara et al. (1989)4)
Monma et al. (1990)8)
Roda et al. (1993)13)
Okuno et al. (1993)11)
Suyama et al. (1996)16)
Sakamoto et al. (1997)14)
Present case

Age/
Sex

Symptoms

Location

Cause

Outcome

64/M
72/M
55/F
0.6/M
56/M
44/F
21/M
1/F
43/M
8/M
66/F
11/M
36/M
31/F
62/F
65/M
44/M
57/M
20/M
21/M
45/M
33/M
64/M
29/F
32/M
21/F
71/F
55/M
57/M
69/F

PND
PND
seizures, headache
no head control
trauma
seizures, headache
headache
seizures, increased ICP
seizures, PND
headache
increased ICP
seizures
seizures
seizures
frontal syndrome
headache
seizures, PND
PND
headache
seizures
PND, increased ICP
seizures, PND
PND
seizures
increased ICP
headache
headache
headache, sensory disturbance
seizures, headache
headache, memory disturbance

occipital
occipital
temporoparietal
cerebellum
frontoparietal
temporoparietal
intraventricular
temporal
parietal
cerebellum
parieto-occipital
frontoparietal
temporal
frontal
frontal
frontal
parieto-occipital
frontoparietal
temporoparietal
parietal
frontoparietal
parietal
occipital
parietal
frontal
frontal
frontal
temporal
frontal
temporal

vascular malformation
vascular malformation
?
?
?
?
?
?
cavernoma
vascular malformation
?
vascular malformation
?
?
?
vascular malformation
?
?
vascular malformation
cavernoma
cavernoma
?
?
cavernoma
cavernoma
cavernoma
cavernoma
?
AVM
?

MD
GR
GR
GR
SD
GR
GR
GR
MD
GR
D
GR
GR
GR
GR
GR
GR
D
GR
?
?
MD
MD
MD
GR
GR
?
GR
GR
GR

AVM: arteriovenous malformation, D: died, GR: good recovery, ICP: intracranial pressure, MD: moderately disabled,
PND: progressive neurological deficit, SD: severely disabled.

evidence of repeated hemorrhage on CT or MR imaging.14)
Histological examinations demonstrated sinusoidal vessels in the capsule in most cases, and the
two layer pattern in the capsule in nine cases.1,3,7,11,
12,14,16) Among these nine cases, sinusoidal vessels
were located in the outer layer in five cases including ours,3,11,14,16) and in the inner layer in the other
four cases.1,7,12) Thus, the clinicopathological characteristics of genuine ECIH may be summarized as the
presence of a distinct fibrous capsule that may consist of two layers, sinusoidal vessels in the capsule,
and expansion of the hematoma with repeated internal bleeding from the capsule.
In our case, initial CT demonstrated a small lowdensity cystic lesion, which indicated that encapsulation of the hematoma was already completed. At
least two hemorrhagic events occurred during the 3
years of follow up. The cause of the initial hemorrhage in our case was not clear. Irregular fibroblastic proliferation has been observed in a thalamic
hematoma secondary to a vascular malformation,10)

Neurol Med Chir (Tokyo) 43, September, 2003

and occult intracerebral vascular malformation may
be responsible for spontaneous intracerebral hematoma with a chronic clinical course.5) We speculate
that the mechanism of the formation of ECIH occurs
as follows. First, the initial small hematoma was
encapsulated by fibrin membrane, followed by the
proliferation of reactive fibroblasts that may have
originated from an occult vascular lesion. Then,
sinusoidal vessels fed by small arteries developed on
the outside of this thin capsule. Leakage of blood,
especially the plasma fraction, from this sinusoidal
layer through the inner rough fibrous tissue resulted
in repeated hemorrhage in the cavity with further
stimulation of fibroblast proliferation and enlargement of the lesion. In addition, the formation of
membrane might be induced by growth factors.9)
This mechanism is similar to that of the outer
membrane of chronic subdural hematoma (CSDH).
The outer membrane of CSDH consists of granulation tissue formed of fibroblasts and capillaries,2)
with many capillary-like vessels in the outer layer of
the capsule, and a few feeding arterioles exist

W. Tsuruta et al.

442

between the dura mater and the capsule.18) These observations are very similar to ours in ECIH except
that CSDH is formed between the dura mater and
pia mater whereas ECIH is located entirely within
the brain parenchyma. The most important factor in
the development of ECIH, as with CSDH,20) is the
sinusoidal vessels of the capsule, which are fragile.
Contact between the hematoma and pia mater may
be correlated with capsule formation, based on the
observation that superficial white matter lesions are
the most frequent.4) However, there was no contact
between the capsule and the pia mater in our case.
ECIH is a rarely reported clinical entity; but cases
may remain unreported, or followed up as possible
low-grade tumors or unknown cystic lesions because of the failure to obtain diagnostic tissue. ECIH
can be surgically removed with excellent outcome.
Histological observation of the capsule suggests that
expansion of the hematoma is caused by repeated
hemorrhage from sinusoidal vessels in the capsule
fed by small arteries.

10)

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Address reprint requests to: K. Tsuboi, M.D., D.M.Sc.,
Department of Neurological Surgery, Institute of
Clinical Medicine, University of Tsukuba, 1–1–1
Tennohdai, Tsukuba, Ibaraki 305–8575, Japan.
e-mail: tsuboi＠md.tsukuba.ac.jp

Neurol Med Chir (Tokyo) 43, September, 2003