ONCOLOGY LETTERS 3: 545-548, 2012
Abstract. We report the case of a 10-year-old girl with a soft
tissue aneurysmal bone cyst (STABC) located in the posterior
aspect of the left shoulder. Conventional radiography revealed an
oblong mass with a calcified rim. On the computed tomography
scan, the lesion appeared to have a non-uniform intralesional
density with an incomplete rim. Magnetic resonance imaging
revealed a multi‑cavity lesion with fluid‑fluid levels. Following
pathological examination, the lesion was diagnosed as a
STABC. This may be only the twentieth reported case in the
English literature of this extremely rare benign tumor occur-
ring in soft tissue. Eight months after surgery the patient was
assessed at our outpatient clinic and found to have excellent
mobility of her left shoulder and no sign of recurrence.
An aneurysmal bone cyst (ABC) is a benign, locally aggres-
sive and expansile tumor that typically occurs in the long
bones or vertebral bodies of children and young adults.
Radiographically, a lytic lesion and expansion are the basic
characteristics of ABC, which usually has well-defined
margins. Histologically, the tumor contains blood‑filled cystic
spaces separated by fibrous septa containing osteoclast‑type
giant cells, fibroblasts and reactive woven bone (1,2).
Previously, ABC was believed to occur exclusively in
bone (3), but in recent years a few cases of soft tissue ABC
(STABC) have been reported (1,4-7). STABC is a recently
recognized extremely rare tumor with fewer than 20 well-
documented cases in the literature (7), as shown in Table I.
We report the imaging and pathological findings of a STABC
in a 10-year-old girl and discuss its differential diagnosis.
Patient and methods
The study was carried out according to the principles of the
Declaration of Helsinki; informed consent was obtained and
Shanghai Ninth People's Hospital Ethics Committee approved
the study. The patient images contained in this article were
captured by a hospital-based photographer at Shanghai Ninth
People's Hospital, Shanghai Jiao Tong University School of
Medicine (8). Permission to use these images in this study has
been obtained from the parents of the girl who participated in
A 10-year-old girl presented with a one-month history of
pain in her left shoulder. She was admitted to hospital as the
pain had increased over the previous 10 days, affecting the
mobility of her left shoulder. Her parents denied any trauma
to the area. Physical examination revealed a 6x5-cm painful
lump in the posterior aspect of the left shoulder; the lump
was solid, smooth and non-pulsatile. Shoulder mobility was
limited; initiative outreach was <80˚, extension was <30˚, and
anteflexion was <30˚. There were no signs of inflammation,
and the white cell count was 5.8x109 cells/l. Serum electrolytes
Radiography indicated a round soft tissue lesion with a
well‑defined calcification margin located at the posterior aspect
of the left shoulder, next to the scapula and proximal humerus.
The adjacent bony structures were not involved, and there was
no significant periosteal reaction on these bones (Fig. 1A).
Computed tomography (CT) revealed an abnormality of the
soft tissue in the left shoulder with an arcuated thin rim with
an ambiguous density, suggesting calcification (Fig. 1B). The
intralesional density was slightly uneven (Fig. 1C).
Magnetic resonance imaging (MRI) revealed a rectangular
5.9x4.6-cm soft tissue lesion in the posterior aspect of the left
shoulder with an uneven intralesional signal. On T1-weighted
MRI, the lesion showed an overall signal intensity (SI) similar
to that of the surrounding normal muscles. The SI of the intra-
lesional septa appeared a little higher than that of the separated
areas (Fig. 2A). By contrast, the mass showed a predominantly
high SI with a well‑defined margin on T2‑weighted MRI; the
SI of the intralesional septa had a low to intermediate SI, while
the separated areas were of high SI (Fig. 2B). Fluid‑fluid levels
were also observed in our patient (Fig. 2C). Following admin-
istration of gadopentetate dimeglumine, the lesion manifested
peripheral and intralesional septa enhancement, while the
separated areas were not significantly enhanced (Fig. 2D).
Soft tissue aneurysmal bone cyst in a 10-year-old girl
YONGQIANG HAO1, LEI WANG1, MENGNING YAN1, FANGCHUN JIN1,
SHENGFANG GE2 and KERONG DAI1
1Department of Orthopaedics Shanghai Key Laboratory of Orthopaedic Implant; 2Department of Ophthalmology,
Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China
Received October 3, 2011; Accepted December 12, 2011
Correspondence to: Professor Yongqiang Hao, Department of
Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant,
Ninth People's Hospital, Shanghai Jiao Tong University School of
Medicine, 639 Zhizaoju Road, Shanghai 200011, P.R. China
Key words: aneurysmal bone cyst, soft-tissue, neoplasm, child,
HAO et al: A SOFT TISSUE ANEURYSMAL BONE CYST CASE
MRI further demonstrated that the scapula and proximal
humerus were not involved and the sclerotin was normal.
The mass was subsequently completely excised under
general anesthesia. Intraoperatively, we found that there was
no relationship between the tumor and the adjacent bones
and the mass was mainly located between the infraspinatus
muscle, teres major muscle and tere muscle (Fig. 3A). On gross
inspection, the specimen was a rectangular 8.8x5.7x4.6-cm
soft tissue mass (Fig. 3B), the exterior of which consisted
of a rim formed partly of fibrous tissue with areas of a thin
eggshell‑like layer of bone (Fig. 3C). The center of the lesion
consisted of irregular blood‑filled cavities separated by septa
of varying thickness (Fig. 3C). Microscopically, the lesion
was composed of cystic blood‑filled spaces. The cyst walls
contained fibroblasts, inflammatory cells, multinucleated giant
cells and reactive woven bones (Fig. 4).
ABC is a type of benign lesion that may occur in any bone,
but rarely in soft tissue. It occurs predominantly during the
first two decades of life. An ABC is composed of numerous
irregular cysts filled with blood and separated by connective
tissue septa containing fibroblasts, osteoclast‑type giant cells
and reactive bone (1,2). It usually appears on radiographs as an
eccentric lytic and expansile lesion with a well‑defined margin
within bones (1).
ABC was first described by Jaffe and Lichtenstein in 1942 (9).
Its development has been widely regarded as a reactive process
since then. However, it is recognized that there is no previous
lesion in the majority of cases of this disease. Panoutsakopoulos
et al (10) demonstrated the presence of a chromosomal trans-
location t(16;17)(q22;p13) in two osseous cases, suggesting a
neoplastic process. These initial findings were later confirmed
by several subsequent cytogenetic studies (11,12). Oliveira
et al (13) reported that the t(16;17)(q22;p13) translocation
fuses the promoter region of the osteoblast cadherin 11 gene
(CHD11) on chromosome 16q22 to the entire coding sequence
of the ubiquitin protease USP6 gene. Ye et al (14) showed
that the overexpression of USP6 in pre-osteoblastic MC3T3
cells is sufficient to drive the formation of tumors that repro-
duced the molecular and histological features of ABC. These
authors also suggested that USP6 may play a direct role in
establishing a degradative and vascularized microenvironment.
Five partner genes known to upregulate USP6 expression in
ABC have been identified: CDH11(16Q22), ZNF9(3Q21),
OMD(9Q22), COL1A1(17Q21) and TRAP(1P34) (15). In
addition, Geiersbach et al (16) reported an ABC case with
an SS18 rearrangement, which has not previously been
described. These findings clearly demonstrate that ABC is a
STABC is extremely rare. The number of published
STABC cases does not exceed 20, with only a few epidemio-
logical and histological reports (7). Of these cases, only 5 are
in the pediatric age group, as shown in Table I. Our patient is
Figure 1. (A) Anteroposterior radiographs of the left shoulder showing a
round soft tissue lesion with a well‑defined calcified margin. (B and C) An
axial CT scan shows a non-uniform soft tissue mass with an incomplete rim
of osseous density. CT, computed tomography.
Figure 2. (A) By axial T1‑weighted MRI, the SI of the lesion is identical
to that of the surrounding muscles; the SI of intralesional septa appeared
a little higher than the separated areas. (B) By axial T2-weighted MRI, the
intralesional septa show low to intermediate SI, while the separated areas are
of high SI. (C) By T2‑weighted MRI, fluid‑fluid levels are present. (D) Axial
T1-weighted MRI following the administration of gadopentetate dimeglu-
mine shows peripheral and intralesional septal enhancement. MRI, magnetic
resonance imaging; SI, signal intensity.
ONCOLOGY LETTERS 3: 545-548, 2012
Table I. Reported cases of soft-tissue aneurysmal bone cyst.
Case Age (years) Site Author and year
Left common carotid
Left upper arm
Left retroclavicular region
Right gluteus medius
Left upper arm
Dal Cin, 2000
The data of the top 15 cases come from reference 5.
Figure 3. (A) The mass was mainly located between the infraspinatus muscle, the teres major muscle and the tere muscle without involving adjacent bones.
(B) The general appearance of the tumor was a rectangular 8.8x5.7x4.6-cm soft tissue mass. (C) Image showing a cross-section of the resected lesion. The
lesion has a well‑defined rim with areas of a thin eggshell‑like layer of bone and is composed of blood‑filled cavities separated by septa of various thicknesses.
Figure 4. Histological features of STABC (hematoxylin and eosin). (A) Photomicrograph showing blood‑filled cystic spaces (magnification, x50). (B) In the
connective tissue septa, some multinucleated giant cells can be observed (magnification, x100). (C) Reactive woven bone can be observed in the fibrous septa
of the STABC (magnification, x100). STABC, soft‑tissue aneurysmal bone cyst.
HAO et al: A SOFT TISSUE ANEURYSMAL BONE CYST CASE
a 10-year-old girl with a lesion in the posterior aspect of the
left shoulder. STABC shows a rather similar appearance to its
osseous counterpart on radiography and MRI (4). In our case,
plain radiographs revealed a rectangular lesion with a fuzzy
image of non-uniform density in the center, when observed
carefully. Although the peripheral rim was not as clear as
described in previous cases, the specific features of ABC on
MRI, including an expansile lesion surrounded by a thin low-
signal rim, increased signal with augmented T1-weighting
and a lobulated contour with fluid‑fluid levels were all clearly
visible in our patient. The MRI presentation of our case may
be described as relatively typical.
The differential diagnosis of STABC mainly includes giant
cell tumor of soft tissue, giant cell tumor of the tendon sheath,
extraskeletal telangiectatic osteosarcoma (EOS) and myositis
Giant cell tumors are often associated with ABCs, since
ABCs often contain a large number of giant cells. These two
diseases are easily confused, and as a result it is occasion-
ally difficult to distinguish ABC from a giant cell tumor,
especially when a giant cell tumor exhibits bleeding, necrosis
and cystic changes. However, giant cell tumors usually occur
in adults over the age of 20, whereas ABCs are often found
in the first two decades of life. However, the results noted
in Table I show that the age of patients with STABC is not
fixed. Histologically, compared with giant cell tumor of soft
tissue or giant cell tumor of the tendon sheath, STABC often
contains more reactive bone-like tissue and woven bone with a
well‑defined peripheral rim, but fewer giant cells.
Differentiation between STABC and EOS is essential
as they require completely different management and have
different outcomes. EOS most commonly affects individuals
older than 30 and is rarely encountered during the first two
decades of life (17). EOS differs from STABC in that it usually
has an ill‑defined rim on X‑rays and is more prone to becoming
malignant. Microscopically, anaplastic tumor cells and atypical
mitosis may be found in EOS, which do not exist in STABC.
Although radiography and CT may reveal certain similari-
ties between STABC and myositis ossificans, i.e., a radiolucent
lesion with a thin rim of ossification at the periphery, the pres-
ence of septa within the lesion in STABC may differentiate it
from myositis ossificans (4). Myositis ossificans usually contain
a solid inner component, whereas STABC does not show the
presence of any solid parts (except for the septa). Nevertheless,
STABC may also be secondary to myositis ossificans. In this
case, cystic spaces filled with blood and connective tissue septa
are also the main points of differentiation.
In conclusion, STABC is an extremely rare type of benign
soft tissue tumor, with no more than 20 cases having been
reported in the English language literature. It is occasionally
secondary to lesions such as giant cell tumor, myositis ossifi-
cans and conventional osteosarcoma, therefore caution should
be used in the diagnosis of STABC. If STABC is correctly
diagnosed, surgical treatment should be implemented with
complete excision considered the most appropriate treatment.
This study was supported by the National High Technology
Research and Development Program of China (863 program)
(grant no. 2009AA03Z311), the National Natural Science
Foundation of China (grant no. 81071472) and the Key
Disciplines of Shanghai Municipal Education Commission
(grant no. J50206).
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