ENGLISH RADIOLOGY
CASE REPORT
“Primary pleuropulmonary synovial sarcoma mimicking a carcinoid tumor”
Directed by :
Muhammad Wahyu Riskhy (P1337430215049)
1B
DIV RADIOLOGY TECHNIQUE
HEALTH POLYTECHNIC OF SEMARANG
2015/2016
Primary pleuropulmonary
synovial sarcoma mimicking a carcinoid tumor
Abstract
Primary
pleuropulmonary synovial sarcoma is a rare malignancy. Commonly described
radiologic features in the literature include pleural disease and/or effusion,
lack of calcification and high uptake on positron emission tomography
computerised tomography. A 68-year-old woman presented with a 3-month
history of cough. Imaging studies showed a right upper lobe mass with internal
foci of calcification, endobronchial extension, and low fluorodeoxyglucose
avidity on positron emission tomography computerised tomography, leading to an
initial diagnosis of carcinoid tumor. However, histologic specimens suggested
an unexpected diagnosis of aggressive synovial sarcoma, and the case was
referred to the sarcoma MDT. Metastatic synovial sarcoma was ruled out, and
radical surgical excision of the lesion was performed. This article highlights
the multiple atypical features of primary pleuropulmonary synovial sarcoma as
seen in this case and reviews imaging findings described in the literature.
Radiologists should be aware of this unusual yet aggressive type of sarcoma.
Introduction
Primary lung
synovial sarcoma is an aggressive malignancy that is rarely encountered in
routine practice and within the Sarcoma multidisciplinary team (MDT), with only
a small number of reported cases in the literature. Nevertheless, radiologists
need to be aware of the imaging findings, differential diagnoses and management
pathway of this entity, as early diagnosis and complete surgical resection are
the most important prognostic factors. Radiology plays an important role in
suggesting the diagnosis, ruling out the most important differential diagnosis
of metastatic synovial sarcoma and following up the patient. We present a rare
case of primary pleuropulmonary synovial sarcoma (PPSS) that was misdiagnosed
initially as a carcinoid tumor. We will summarize the literature findings about
primary lung synovial sarcoma emphasizing the pertinent radiologic features and
compare them to the atypical features seen in our case. The aim of this article
is to familiarize the reader with the radiologic features and imaging pitfalls
of this rare malignancy, as early recognition and complete surgical resection
are crucial for the best outcome.
Case report
A 68-year-old woman presented to the Chest clinic with
a persistent cough of 3-month duration. There was no history of hemoptysis,
smoking, or other significant medical history. Clinical examination was unremarkable.
A chest radiograph showed a well-defined mass in the right upper zone.
Subsequently, she had an urgent contrast-enhanced CT scan of the chest,
abdomen, and pelvis confirming a 5.6 × 5.4 × 5-cm soft tissue mass in the right
upper lobe with an endobronchial component filling the right upper lobe
bronchus extending approximately 1 cm distal to the carina. The lesion
demonstrated mainly soft-tissue attenuation (42-50 Hounsfield units) with
internal specks of course calcification. There was secondary atelectasis of the
anterior segment of the right upper lobe. No enlarged thoracic lymph nodes or
other lesions were seen. The visualized skeleton was normal. Positron emission
tomography computerised tomography low fluorodeoxyglucose (FDG) activity with a
maximum standardized uptake value of 3.8 within the lesion. No other areas of
abnormal uptake were present. The initial clinical and radiologic impressions
were pulmonary carcinoid tumor. However, histologic assessment of a
transbronchial biopsy suggested a synovial sarcoma. The case was discussed at
both the lung and soft-tissue sarcoma MDT, and the concluding diagnosis was
PPSS. The patient underwent complete surgical excision. The surgical specimen
showed grade 3 PPSS with negative resection margins. The patient had an
uneventful recovery and is currently being followed up with 6-monthly CT scans.
Adjuvant therapy was considered unnecessary in view of the complete surgical
resection.
Fig. 1.
PPSS in a
68-year-old woman. Posteroanterior chest radiograph demonstrating right upper
zone well defined mass abutting the right trachea. There is volume loss of the
right upper lobe with tracheal shift to the right.
Fig. 2.
PPSS in a
68-year-old woman. (A) Axial contrast-enhanced CT scan of the thorax
demonstrating a well defined, heterogeneous mass in the right upper lobe with
internal septation, and peripheral thin enhancing rim. (B)
Coronal-reconstructed image shows multiple well-defined foci of calcification.
Fig. 3.
PPSS in a
68-year-old woman. (A) Axial contrast-enhanced CT scan of the thorax (lung
window) showing right upper lobe bronchus endobronchial tumor extension and
associated right upper lobe anterior segment atelectasis. (B)
Sagittal-reconstructed image (lung window) showing the position of the tumor in
the posterior segment of right upper lobe abutting the oblique fissure with
atelectasis of the anterior segment of right upper lobe.
Fig. 4.
PPSS in a 68-year-old woman. (A,B) Fused axial images of positron emission tomography computerised, tomography scan showing low fluorodeoxyglucose avidity of the right upper lobe tumor with endobronchial extension and a focus of calcification.
Discussion
Synovial sarcoma is a type of spindle cell tumor
accounting for 2.5%-10% of all soft-tissue sarcomas. It is primarily seen in a
para-articular location within the extremities in adolescents and young adults,
with a slight predilection for the knee joint. Rare sites include the head and
neck, mediastinum, lung, pleura, and chest wall 1 and 2. Primary pulmonary sarcoma is rare
constituting approximately 0.5% of primary lung malignancies 2 and 3. The synovial subset of primary
lung sarcoma is very rare with a limited number of reported cases in
literature. It is often difficult to determine the exact site of the primary
tumor in terms of whether it is pleural or parenchymal, and therefore, it is
often referred to as PPSS. PPSS usually affects people in the 4th or 5th decade
of life 1, 4 and 5 with a reported age ranged
between 9 and 77 years. The literature either describes no specific sex
predilection 2, 5 and 6 or a slight male predominance 1, 3 and 7. Clinical symptoms include dyspnea,
cough, chest pain, and hemoptysis 1, 2, 5, 6 and 8. No definite risk factors have been
established, although there is a case report of PPSS after radioactive iodine
therapy for thyroid cancer. No relation to cigarette smoking has been
established .
PPSS is a mesenchymal tissue cell tumor.
Macroscopically, it consists of uniform or nodular solid soft-tissue component
intermingled with variable necrotic and hemorrhagic components. Surrounding
pleural adhesions and a capsule are described in few cases. Microscopically, it
has 4 histologic subtypes including monophasic fibrous (spindle), monophasic
epithelial, biphasic, and poorly differentiated. Monophasic subtypes are the
most common 1, 2, 7 and 10. Immunohistochemistry is positive
for Bcl-2 protein in approximately 79% of cases 2 and 10, and cytogenetic analysis
demonstrates a characteristic chromosomal translocation t(x;18)(p11;q110) in
90% of cases 1, 2 and 8. Historically, the nomenclature of
synovial sarcomas is because of the impression of associated synovium, with the
epithelial components representing synovial slits. However, these neoplasms
have no established relationship to synovial tissue, making the terminology of
“synovial sarcoma” a misnomer .
Although PPSS is often detected on a chest radiograph,
the plain radiographic findings are not specific and indistinguishable from
other primary lung tumors . Plain radiographic detection and appearance
depend on the site and size of the lesion. Although distinction between primary
parenchymal or pleural disease can be difficult, parenchymal predominant
synovial sarcoma will usually manifest as a well defined, rounded mass, or less
commonly as a consolidation with rather ill-defined margins. Pleural synovial
sarcoma is usually seen as a pleural-based mass or an area of pleural
thickening 1, 2 and 5. An associated ipsilateral pleural
effusion is very common and described in multiple cases 1, 2 and 5 and may be related to acute or
recurrent hemothorax 1 and 11. Pneumothorax is uncommon and only
seen in a few cases5 and 11. Interestingly, our case did not
demonstrate any pleural effusion. Large tumors can cause significant or
complete opacification of the involved lung and mediastinal shift2 and 5. In a review of 5 cases, the
smallest tumor measurements were 6 × 5 × 6 cm, and the largest tumor
measurements were 14 × 15 × 19 cm . The range of the maximum measurement of
tumors in a review of 12 cases was 5-20 cm with an average value of
10 cm .
PPSS is usually seen as a heterogeneous mass on
nonenhanced CT because of a combination of solid and cystic components.
Contrast-enhanced CT will show a heterogeneous enhancement pattern usually involving
the nodular soft tissue, and a nonenhancing, cystic and/or necrotic component.
A thin, irregular enhancing peripheral rim is also a common feature 1, 2, 4 and 11. Septation is uncommon
and only described in 2 cases . A surrounding rim of ground glass changes
can be seen on CT 5 and 12. Our case appeared
as a heterogeneous lesion with multiple thin enhancing septae.
Internal calcification apparent on imaging is very
rare and described only in one case. A separate case reported calcification
that was only visible on the gross specimen after surgical excision but not
radiologically . Multiple foci of calcification, which led to the initial
diagnosis of carcinoid tumor, are seen in the presented case. Although internal
calcification is rare, it can be seen in PPSS, and hence, the diagnosis should
not be excluded. It is worth mentioning that calcification is often present in
metastatic synovial lung carcinoma, which is the most important differential
diagnosis considering the lungs are involved in 94% of metastatic synovial
sarcomas.
The tumor does not have a specific predilection for a
certain lung lobe. However, upper lobe lesions were common in one case series.
Metastasis is usually hematogenous rather than lymphatic and enlarged thoracic
lymph nodes secondary to disease involvement are extremely rare. To our
knowledge, there is only one reported case of PPSS with lymph node metastasis,
which was in a paraesophageal location.
Metastatic pleural nodular disease and bone
involvement can be seen 2 and 14. However, obvious chest wall
muscular involvement or bony cortical destruction favors a synovial sarcoma
arising from the chest wall 5 and 14.
Although positron emission tomography computerised
tomography imaging often shows increase uptake within the lesion 2 and 5, our case only demonstrated low
fluorodeoxyglucose avidity mimicking a carcinoid tumor.
Magnetic resonance imaging usually shows a
heterogeneous tumor that is predominately low to intermediate signal on
T1-weighted images and high signal on T2-weighted images 2 and 4. Fluid–fluid levels due to
hemorrhage or necrosis are also reported. Gadolinium administration usually
shows heterogeneous internal and peripheral rim enhancement 2 and 4.
The most important differential diagnosis is
metastatic synovial sarcoma as the lung is the most common site for metastasis,
affected in 94% of metastatic cases 2 and 14. Since both primary and metastatic
lung synovial sarcoma will have similar histologic and cytogenetic findings,
radiology and clinical assessment play the most important role in
differentiation between the two. Other differentials include primary and
metastatic lung neoplasms, localized pleural fibrous tumor, mesothelioma in
cases of pleural disease, and other rare primary parenchymal sarcomas. The
presence of hilar or mediastinal enlarged lymph nodes suggests a diagnosis
other than PPSS 2 and 5.
PPSS is more aggressive than soft-tissue synovial
sarcoma, possibly because of a relative larger size and later
presentation with reported survival figures of 6-58 months from
diagnosis 3 and 5. Factors indicating good outcome
are tumor size <5 cm, low mitotic rate, absent necrosis, and complete
surgical excision. In one study of 12 patients with primary pleuropulomonary
synovial sarcoma (follow-up 12 months-5years, mean 21 months), 5 patients died
within 2.5 years from the diagnosis and the local recurrence was seen in 75% of
patients within the first 2 years. In 80% of patients, the local recurrence
involved either the surgically treated lobe or the ipsilateral residual lobes.
Distant metastasis is often hematogenous and rarely lymphatic. Reported distant
metastatic sites include the bone, heart, and brain 1, 10, 17, 18, 19 and 20. Rare complications include
Pancoast’s syndrome and pulmonary artery pseudoaneurysm because of tumor
invasion 3 and 15.
Surgical excision, often in the form of lobectomy or
pneumonectomy, is the most accepted treatment method aiming for complete tumor
resection. This is strongly associated with increased survival .
Radiotherapy and chemotherapy are often used as adjuvant treatment
options 1 and 5.
MAIN IDEA
1. Primary lung
synovial sarcoma is an aggressive malignancy that is rarely encountered in
routine practice and within the Sarcoma multidisciplinary team (MDT), with only
a small number of reported cases in the literature.
2. Clinical
examination was unremarkable, a chest radiograph showed a well-defined mass in
the right upper zone..
3. Positron
emission tomography computerised tomography low fluorodeoxyglucose (FDG)
activity with a maximum standardized uptake value of 3.8 within the lesion.
4. Synovial
sarcoma is a type of spindle cell tumor accounting for 2.5%-10% of all
soft-tissue sarcomas.
5. PPSS is a
mesenchymal tissue cell tumor,macroscopically consists of uniform or nodular
solid soft-tissue component intermingled with variable necrotic and hemorrhagic
components.
6. PPSS is
often detected on a chest radiograph, the plain radiographic findings are not
specific and indistinguishable from other primary lung tumors.
7. Internal
calcification apparent on imaging is very rare and described only in one case.
8. The tumor
does not have a specific predilection for a certain lung lobe.
9. PPSS is more
aggressive than soft-tissue synovial sarcoma, possibly because of a relative
larger size and later presentation with reported survival figures of 6-58
months from diagnosis 3 and 5.
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semoga post ini berguna buat anda semua, kususnya di bidang radiologi
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