Intracranial Primary Synovial Sarcoma: Radiologic ... - SAGE Journals

The Neuroradiology Journal 21: 362-367, 2008

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Intracranial Primary Synovial Sarcoma: Radiologic-Pathologic Correlation V.K. KATSAROS*, A.-A. KATSAROU**, A. PAPADOPOULOU***, D. FLOROS****, N. MARANGOS*** * Department of Neuroradiology, CT and MRI, IKA Oncology Hospital; Athens, Greece ** Department of Radiology, Red Cross Hospital; Athens, Greece *** Center of Otorhinolaryngology, Head & Neck Surgery and Skull Base Surgery; Athens, Greece **** Pathology Department “Micromedica”; Athens, Greece

Key words: intracranial synovial sarcoma, petrous bone, MRI

SUMMARY – We present a very rare case of spontaneous intracranial synovial sarcoma. A 15-yearold female was admitted to our institution for a cervical spine MRI, reporting a gradual pain of the dorsal neck after an injury three months previously. After obtaining the first sequence we discovered a large skull base mass. We immediately performed a skull base MRI. MR arteriography, MR venography, CT and DSA were also performed. A large space-occupying lesion was demonstrated, extending from the right petrous bone to the occipital bone at the level of the foramen magnum and the right atlantooccipital junction. CT revealed calcifications. The MR venography demonstrated diminished flow in the right transverse and sigmoid sinus, as well in the right internal jugular vein. Otorhinolaryngological evaluation revealed a slight ipsilateral conductive hearing loss. The whole mass was macroscopically removed via a retrosigmoid, transmastoid, infratemporal approach. Postoperative course was uneventful, except for complete palsy of the ipsilateral hypoglossal nerve. The final pathological examination including immunohistochemical picture, showed findings consistent with synovial sarcoma (monophasic spindle-cell type).

Introduction Synovial sarcoma is a clinically and morphologically well defined entity of mesenchymal origin so named for its histological similarity to the synovium 1. It occurs primarily in the para-articular regions, usually in close association with tendon sheaths, bursae and joint capsules, and less frequently in fascial structures, aponeuroses or ligaments. On rare occasions it is also encountered in areas without any apparent relationship to synovial structures, as in the parapharyngeal region or abdominal wall 1,2. It is considered the fourth most common type of sarcoma (7-10%) after malignant fibrous histiocytoma, liposarcoma and rhabdomyosarcoma. There are three histological variants: the classical biphasic, monophasic fibrous type and monophasic epithelial type (the biphasic and monophasic fibrous types are equally common). Clinical signs are subtle and at times existing many years before diagnosis. 362

The course of the disease is slow and insidious. The most typical presentation is that of a palpable deep-seated swelling or mass associated with pain or tenderness. As in other types of sarcoma, the principal sites of metastases are in the lung that can appear many years after the initial diagnosis. Case Report A 15-year-old female was admitted to our institution reporting a gradual pain of the dorsal neck that initiated after an injury three months before. She also complained of swelling in the right upper neck and came to us for a cervical spine MRI. Already during the scout view to plan the cervical spine MRI, a large mass was observed, extending from the petrous bone and the skull base to the upper neck, suboccipital also involving the soft tissues of the dorsal neck. The cervi-

V.K. Katsaros

Intracranial Primary Synovial Sarcoma: Radiologic-Pathologic Correlation

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Figure 1 A-D Brain MRI demonstrates a space-occupying lesion with relatively normal and discrete margins. The signal intensity behaviour is inhomogeneous in all sequences. Compression of the spinal cord, medulla oblongata and right cerebellar hemisphere is also present. The mass extends from the right petrous bone to the occipital bone at the level of the foramen magnum and the right atlantooccipital junction. After i. v. Gd chelate administration the lesion shows intense inhomogeneous enhancement and was described more precisely. A) Transverse T2-weighted image. B) Transverse gadolinium enhanced T1-weighted image: C) Coronal STIR image. D) Coronal gadolinium enhanced T1-weighted image with fat saturation.

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Figure 2 A) Brain-CT demonstrates the mass destroying the petrous and occipital bone and eroding the clivus as well as the atlantooccipital junction. Note the presence of amorphous calcifications within the mass. B) Skull base MR venography showing compression of the right transverse, sigmoid sinus and the right internal jugular vein resulting in diminished blood flow in the above mentioned anatomic regions.

cal spine MRI was normal. Thus, we performed a skull base MRI after informing the patient and her parents. In between we questioned the patient more closely about her symptoms and as she showed us where exactly she felt the pain, a palpable mass was detected. The skull base MRI included T2-, proton density, STIR images, T1-weighted images and T1-W fat saturation images, before and after i. v. Gd 364

chelate administration. The dimensions of the space-occupying lesion were 7.3 cm (anteroposterior) X 3.6 cm (transverse) X 4 cm (caudocranial). The margins were normal and discrete, and the signal intensity behaviour was inhomogeneous in all sequences. The presence of haemorrhagic, cystic and fibrotic elements was established by MRI. Mass effect and compression of the spinal cord, medulla oblongata and

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right cerebellar hemisphere were also present. The mass extended from the right petrous bone to the occipital bone at the level of the foramen magnum and the right atlantooccipital junction, showing erosions of all the above mentioned bony structures of the skull base. The medial bony limit of the mass was the clivus. After i. v. Gd chelate administration the lesion showed intense inhomogeneous enhancement and was described more precisely (figure 1). Our differential diagnosis, based on MRI characteristics and topography of the lesion, included paraganglioma of the right jugular bulb, atypical neurinoma of the IX-XII cranial nerves, atypical meningioma and clivus chordoma. Skull base CT as well as MR arteriography and MR venography were performed. CT revealed calcifications in the lesion. MR arteriography was normal. MR venography demonstrated diminished flow in the right transverse and sigmoid sinus, as well in the right internal jugular vein, representing compression by the space-occupying lesion (figure 2). These findings were confirmed by the DSA performed the following day. Furthermore the DSA excluded the possibility of a right jugular paraganglioma. Otorhinolaryngological evaluation revealed a slight ipsilateral conductive hearing loss, whereas cranial nerve function was absolutely normal. An open biopsy of the soft tissue elements of the mass in the dorsal neck was performed under local anaesthesia and the histological diagnosis was sarcoma, probably synovial sarcoma. The whole mass was macroscopically removed via a combined retrosigmoid, transmastoid, infratemporal approach (figure 3). After histological examination of the whole tumor, the final pathological picture showed findings consistent with synovial sarcoma (monophasic spindle-cell type). Pathological differential diagnosis also included rhabdomyosarcoma, leiomyosarcoma, neurinosarcoma, malignant fibrous histiocytoma, malignant meningioma and melanoma, which were excluded immunohistochemically (figure 4). Postoperative course was uneventful, except for a complete palsy of the ipsilateral hypoglossal nerve. The patient underwent combined chemotherapy and radiotherapy for several months, followed also by brachytherapy. Unfortunately one year after the first MRI examination, the follow-up CT of the thorax demonstrated pulmonary as well as bone me-


tastases and two months later (August 2006) the patient passed away. Discussion Soft tissue sarcoma accounts for 0.7% of all malignant tumors in men and 0.6% in women. Synovial sarcoma is a soft tissue malignant neoplasm that arises from tissue derived from the primitive mesenchyme. It accounts for approximately 7-10% of all soft tissue tumors and is the fourth most common type of sarcoma following malignant fibrous histiocytoma, liposarcoma and rhabdomyosarcoma. Only 3% arise in the head and neck region 3. Synovial sarcoma typically presents as a soft tissue mass of upper or lower extremity, pelvic or groin region, or retroperitoneal space. The lung is the most common site for the first metastasis of the disease, followed by bone and regional lymph nodes. Incidence of local recurrence lies in between and depends on clear margins after removal. Synovial sarcoma presenting as an intracranial mass is extremely rare. Kleinschmidt-DeMasters et Al 4 reported the case of a 19-yearold woman with primary synovial sarcoma of the third ventricle. Buono et Al described a 43year-old woman with a synovial sarcoma of the right forearm, which metastasized to the right orbit and ipsilateral cavernous sinus 5. Bettio et Al referred a 36-year-old man with an intracranial tumor largely involving the cranial base, invading the sellar region, and extending into the sphenoidal sinus 6. We are unaware of previous reports of primary synovial sarcoma of the atlanto-occipital junction extending to the petrous bone and compressing the brainstem and could find no reference to it in a MEDLINE® literature search. The treatment of synovial sarcoma includes surgical excision and adjuvant therapy with radiation and/or chemotherapy. Synovial sarcoma of the head and neck region seems to have a better prognosis than synovial sarcoma of the extremities, with 5-year survival rates ranging from 47% to 82%. The median time of survival after recurrence is 15 months, with a five-year survival rate of 11.5%. Although rare, primary synovial sarcoma of the skull base and especially of the atlanto-occipital junction and the petrous bone should be considered in the differential diagnosis of space-occupying lesions of the skull base. 365


Figure 3 Surgical planning and excision.

Figure 4 A) Monophasic fibrous synovial sarcoma infiltrating striated muscles (left corner), H+E. B) Spindle cells with ovoid hyperchromatic nuclei and frequent mitoses (4 around the center), H+E. C) Tumor showing positive immunostaining for vimentin in most of the cells. D) Tumor showing positive immunostaining for keratin in many cells.

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References 1 Narvaez JA, Narvaez J, Aguilera C et Al: MR imaging of synovial tumors and tumor-like lesions. Eur Radiol 11: 2549-2560, 2001. 2 Waldt S, Rechl H, Rummeny EJ et Al: Imaging of benign and malignant soft tissue masses of the foot. Eur Radiol 13: 1125-1136, 2003. 3 Rangheard AS, Vanel D, Schwaab G et Al: Synovial sarcomas of the head and neck: CT and MRI findings of eight patients. Am J Neuroradiol 22: 851-857, 2001. 4 Kleinschmidt-DeMasters BK, Mierau GW, Sze CI et Al: Unusual dural and skull-based mesenchymal neoplasms: a report of four cases. Hum Pathol 29: 240-245, 1998. 5 Buono LM, Silberschmidt A, Foroozan R et Al: Metastatic synovial sarcoma to the skull base and orbit. Am J Ophthalmology 134: 785-787, 2002.

6 Bettio D, Rizzi N, Colombo P et Al: Unusual cytogenetic findings in a synovial sarcoma arising in the paranasal sinuses. Cancer Genet Cytogenet 55: 79-81, 2004.

Vasileios K. Katsaros, MD Voutsina str. 77-79 15561 Holargos Athens, Greece Tel.: +30-6932741811 E-mail: [email protected]

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