Contrast‑enhanced ultrasound aids in the detection of prostate rhabdomyosarcoma: A case report and literature review

Abstract

Prostate sarcoma is a rare malignancy with an extremely poor prognosis. The extremely low morbidity and atypical clinical symptoms contribute to a missed diagnosis. The typical features of prostate sarcoma in transrectal ultrasound (US) and magnetic resonance imaging, such as a markedly enlarged volume and irregular prostatic contours, cannot usually be found until dysuria or even uroschesis occurs, and may then be too late to treat. However, there appears to no specific tumor marker for the disease in the serum. The present study reports a case of a young male patient who was diagnosed with prostate rhabdomyosarcoma. This was, to the best of our knowledge, the first case of this diagnosis using contrast‑enhanced US (CEUS) when the symptoms were not severe. In this case, the intralesional non‑enhancement areas and rim‑like hyper‑enhancement around the lesion were considered to be the main CEUS features of prostate rhabdomyosarcom. The present study also reviews the associated literature.

Full text

ONCOLOGY LETTERS 10: 1541-1544, 2015
Abstract. Prostate sarcoma is a rare malignancy with an
extremely poor prognosis. The extremely low morbidity and
atypical clinical symptoms contribute to a missed diagnosis.
The typical features of prostate sarcoma in transrectal
ultrasound (US) and magnetic resonance imaging, such as a
markedly enlarged volume and irregular prostatic contours,
cannot usually be found until dysuria or even uroschesis occurs,
and may then be too late to treat. However, there appears to
no specic tumor marker for the disease in the serum. The
present study reports a case of a young male patient who was
diagnosed with prostate rhabdomyosarcoma. This was, to the
best of our knowledge, the rst case of this diagnosis using
contrast-enhanced US (CEUS) when the symptoms were not
severe. In this case, the intralesional non-enhancement areas
and rim-like hyper-enhancement around the lesion were
considered to be the main CEUS features of prostate rhabdo-
myosarcoma. The present study also reviews the associated
literature.
Introduction
Prostate sarcoma is a rare malignancy accounting for <1%
of all primary prostate malignancies in adults (1). It has an
extremely poor prognosis, with a median overall survival time
of 23 months, partly due to the difculty of early detection.
The early clinical symptoms, such as dysuria or abdomen
pain, are unspecic and there is no specic serum marker
for the entity, thus it is always rstly detected by imaging (2).
Imaging-guided biopsy is the standard diagnostic tech-
nique used to identify prostate sarcoma (3). In recent years,
contrast-enhanced ultrasound (CEUS), which can depict the
micro- and macro-vascularity of prostate, has been proved
effective in detecting prostate adenocarcinoma (4,5). However,
to the best of our knowledge, the CEUS features of prostate
sarcoma remain unknown. Thus, the current study presents
a case of prostate rhabdomyosarcoma, with emphasis on the
CEUS ndings. The associated literature on prostate sarcoma
is also reviewed. Written informed consent was obtained from
the patient.
Case report
A 33-year-old male was referred to the Department of Ultra-
sound (Shanghai Tenth People's Hospital, Shanghai, China)
in March 2014 due to frequent micturition, accompanied
with a low‑grade fever (37.5˚C) and lower abdomen pain.
Prior to this, the patient had been treated for prostatitis in a
community hospital for 3 months, but without evident remis-
sion. No abnormal laboratory test findings were recorded,
with the exception of a grade of 1+ for urinary occult blood
upon urinalysis. The prostate-specific antigen (PSA) level
(1.26 ng/ml) was within normal limits. Other symptoms, such
as frequent micturition and a poor urinary stream were present
occasionally. Local stenosis of the rectum was suspected upon
digital rectal examination. There was no family history of
genitourinary cancer.
Transrectal US (TRUS) was performed with a
LOGIQ E9 scanner (GE Healthcare, Milwaukee, WI, USA),
which was equipped with a transrectal transducer (E8C;
5-9 MHz). The patient was examined in the left recumbent
position, with slightly bent knees. The prostate was enlarged
asymmetrically on gray-scale US imaging, measuring
~7.0x5.1x5.2 cm in size. The volume (V) of the prostate was
computed to be 97 ml when using the following formula:
V = π x L x W x H / 6, where L is the length, W is the width
and H is the height of the prostate. The left lobe of the prostate
was protruding with a well-delineated margin, and the left
lobe was markedly larger (volume, 78 ml) than the right lobe
(volume, 18 ml). The prostatic urethra and ejaculatory ducts
were pushed to the right and were not clearly shown (Fig. 1A).
The left lobe was heterogeneous in echogenicity on US, with
irregular small hypoechoic areas. Color Doppler imaging
showed dotted blood ow within the left lobe (Fig. 1B).
Transrectal elastography was performed with the same
scanner to provide information on stiffness. The peripheral zone
of the left lobe was displayed in blue, indicating tissue compo-
nents with relatively hard stiffness. The central zone of the left
lobe was mainly displayed green (i.e., intermediate stiffness),
Contrast‑enhanced ultrasound aids in the detection of prostate
rhabdomyosarcoma: A case report and literature review
LE-HANG GUO, HUI-XIONG XU, HUI-JUN FU, LI-PING SUN and BO‑JI LIU
Department of Medical Ultrasound, Shanghai Tenth People's Hospital of Tongji University, Shanghai 200072, P.R. China
Received September 3, 2014; Accepted May 20, 2015
DOI: 10.3892/ol.2015.3449
Correspondence to: Professor Hui-Xiong Xu, Department of
Medical Ultrasound, Shanghai Tenth People's Hospital of Tongji
University, 301 Yanchangzhong Road, Shanghai 200072, P.R. China
E-mail: xuhuixiong@hotmail.com
Key wo rds: prostate rhabdomyosarcoma, contrast-enhanced
ultrasound, ultrasound

GUO et al: CONTR AST-ENHANCED ULTRASOUND AND PROSTATE SARCOMA
154 2
with red or yellow patch-like areas (i.e., soft or low stiffness).
The right lobe was mainly displayed in green (Fig. 1C).
CEUS was performed subsequent to the injection of 2.4 ml
contrast agent (SonoVue, Bracco, Milan, Italy) followed by
10 ml of normal saline ush through the antecubital vein.
Early arterial enhancement started from the edge of the left
lobe at 11 sec after contrast injection. There was rim-like
hyper-enhancement surrounding the left lobe (Fig. 1D).
Figure 1. Transverse directional views of the prostatic left lobe on tra nsrectal US (white arrow). (A) Gray-scale US: An enlarged prostate with irregular inter nal
hypoechoic regions. The distorted middle line was also shown, but the prostate ureth ra and ejaculatory ducts were not clear. (B) Color doppler imaging: Dotted
blood ow within the left lobe. (C) Elastography: The peripheral zone of the left lobe was displayed in blue, and the central zone of the left lobe was mainly
displayed in green, with red patch-like areas. (D) Arterial phase (11 sec): Enhancement sta rted from the edge of the left lobe (red arrow). (E) Venous phase
(52 sec): Contrast agent had extended inward the left lobe and formed hyper-enhancement zones, but had not extended into the other region. (F) Late phase
(150 sec): Contrast agent washed out slowly and had not extended inward the non-enhancement zone. US, ultrasound.
Figure 2. Transverse directional views of a mass on magnetic resonance imaging (MRI) and the pathological gross specimens (white arrow). (A) T1-weighted
image: A well‑dened and large mass was detected in the pelvis, with isointense signals (white arrow). (B) T2‑weighted image: A well‑dened and la rge
mass was detected in the pelvis, with increased signals and more marked heterogeneity (white arrow). (C) Contrast-enhanced MR I: The heterogeneous
hyper-enhancement was simila r with contrast-enhanced ultrasound (CEUS; white arrow). (D) Light microscopic examination for biopsy: Fascicles of primi-
tive, undifferentiated and diffusely distributed spindle cells [hematoxylin and eosin (HE) staining; magnication, x40]. (E) Pathological gross specimens: The
tumor specimen (cut open) was soft, fragile and moist, with local inter nal hemorrhage (black arrow), exactly where CEUS contrast agent started to diffuse
into the tumor. A pseudo-capsule wrapped around the tumor was also observed (white arrow). (F) Light microscopic examination for gross specimens:
Hypercellula r mesenchymal tumor composed of strap and tadpole cells with eosinoph ilic brillary cytoplasm (HE staining; magnication, x100).

ONCOLOGY LETTERS 10: 1541-1544, 2015 154 3
Following this, the contrast agent extended immediately inward
and formed a number of hyper-enhancement zones that were
irregular, but not isolated (Fig. 1E). The contrast agent washed
out slowly and the hyper-enhancement lasted during the whole
arterial (<30 sec), venous (31-120 sec) and late (121-180 sec)
phases. Adversely, contrast agent never extended into the other
region of the left lobe (Fig. 1F). The non-enhancement area
was mainly at the center and posterior of the left lobe, with an
irregular shape, which corresponded to the intermediate and low
elasticity areas on elastography examination, and the irregular
hypoechoic areas on baseline US.
Based on the results of CEUS, the ‘left lobe’ was supposed
to be a rare malignant neoplasm with high condence. Hence,
the patient was admitted to hospital immediately and a biopsy
was performed. Only 4 samples were obtained (2 from the upper
pole and 2 from the lower pole), which were pale and fragile,
with high moisture contents.
Prior to the biopsy, a series of pre-operative examinations,
including abdominal and pelvic magnetic resonance imaging
(MRI), chest radiographs, bone scintigraphy and certain serum
tests, had been performed to evaluate the tumor staging. The
MRI depicted a pelvic mass measuring ~5.4x5.6x5 cm in size,
which was well dened, pushed the urethra to the right and
compressed the left seminal vesicle observably. The tumor
revealed isointense signals on T1-weighted imaging (Fig. 2A)
and increased signal intensity on T2-weighted imaging, with
heterogeneity (Fig. 2B). Multiple small high signal intensity
areas distributed inside the mass were considered to be cysts.
Following intravenous gadolinium administration, heteroge-
neous hyper-enhancement was noted (Fig. 2C). The diagnosis
was a malignant lesion in the pelvic cavity, without a precise
location, and no abnormal iliac lymph nodes were noted. The
remaining scans and serum tests negative.
The biopsy samples were analyzed by an experienced pathol-
ogist and showed mixed bundles of primitive, undifferentiated
and diffusely distributed cells. Cytological atypia was moderate,
but the mitotic activity was high. Necrotic tissues were noted in
these samples (Fig. 2D). Immunohistochemical studies showed
that the neoplastic cells were positive for muscle‑specic actin,
fast myosin and vimentin, whereas the cells were negative
for desmin, keratin AE1/AE3, cytokeratin 5/6, PSA and pros-
tate‑specic acid phosphatase. All pathological manifestations
proved that the patient had a subtype of prostate sarcoma.
The patient underwent a radical prostatectomy. The whole
prostate, seminal vesicles, urethral bulb and soft tissue adjacent
to the prostate were totally removed. Macroscopically, the
complete tumor was soft, fragile, moist with internal hemor-
rhage and encased by a pseudo‑capsule (Fig. 2E). The nal
pathological diagnosis was of a rhabdomyosarcoma (Fig. 2F)
with large necrotic areas. At 12 days post-surgery, the patient
recovered well and was discharged in a stable condition. To date,
the patient has nished 8 courses of chemotherapy (cisplati n and
bleomycin were administered using bladder irrigation) and is
alive with no signs of recurrence or metastases.
Discussion
Adult prostate sarcoma is extremely rare, with a morbidity
rate of 0.1-0.2% in all prostate tumors (6), which is far below
the morbidity rate of prostate adenocarcinoma (7). The main
subtypes of prostate sarcoma consist of leiomyosarcoma,
rhabdomyosarcoma, synovial sarcoma, brosarcoma, spindle
cell sarcoma, prostatic stromal sarcoma and undifferentiated
sarcoma (6). Rhabdomyosarcoma usually occurs in young men,
particularly in children as the most common subtype (8). This
high-grade malignant tumor with a dismal prognosis grows fast
and invasively (6), and is prone to bleeding, necrosis or cystic
degeneration. Sarcomas often metastasize hematogenously in
the early stage due to the nutrient-rich blood supply (9). Early
diagnosis and surgical resection with a curative intent offers
patients the best chance of survival (10).
However, for the majority of urologists or radiologists,
their experience of this diagnosis is limited. The initial clinical
symptoms are usually unspecic unless urinary obstruction
may increase the clinician's vigilance (11). Additionally, there
appears to be no specific tumor marker for sarcoma in the
serum (12). Due to these issues, an early diagnosis is extremely
difcult, resulting in a dismal prognosis (2).
Ultrasound, MRI and cytology findings in the urine are
reported as methods for the detection of prostate sarcoma, On
TRUS, a markedly enlarged volume and irregular margins
are important characteristics of prostate sarcoma (13,14). In
addition, TRUS is usually used to guide a biopsy to conrm
the diagnosis (1). The imaging features of MRI, such as a large
size, irregular margins and heterogeneity, are similar to those
of TRUS (15,16). Besides that, it has an advantage in detecting
metastatic lesions and revealing the adjacent structures (17).
Cy tolog y nd ing s in th e urin e may be usef u l, but are also va r ied,
therefore their use is not indicated as a routine procedure (18).
In the present case, the volume and margin of the tumor on
TRUS were not typical, as previously reported (3,13). Due to t he
benets of using CEUS, unusual features such as intralesional
non-enhancement areas and rim-like hyper-enhancement
around the lesion were revealed, so that timely and effective
treatment was performed. In addition, only 4 biopsy samples
were obtained from the hyper-enhancement areas on CEUS.
This avoided the unnecessary trauma to the patient and
the risk of metastasis whenever possible. In the majority of
situations, at least 12 cores will be sampled due to the large
volume (19).
As aforementioned, due to the extremely low morbidity
of prostate sarcoma, it is not necessary to perform CEUS
routinely. Under certain situations, for example, a markedly
enlarged volume, an irregular and asymmetrical appearance,
marked heterogeneity internally or other abnormal signs in
the prostate, CEUS may be useful as a rapid diagnostic test,
particularly in young patients. Likewise, CEUS is useful
to determine the biopsy sites to decrease any unnecessary
trauma and risks of metastasis. Surgery, chemotherapy and
radiotherapy are the main methods of treatment. Among them,
surgical resection is the most recommended. In conclusion,
this present case of prostate rhabdomyosarcoma benetted
from the application of CEUS.
Acknowledgements
This study was supported in part by grants from the Key
Project of the Shanghai Health Bureau (no. 20114003) and the
Shanghai Talent Development Project of the Shanghai Human
Resource and Social Security Bureau (no. 2012045).

GUO et al: CONTR AST-ENHANCED ULTRASOUND AND PROSTATE SARCOMA
154 4
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