Synovial Sarcoma of Peripheral Nerves: Analysis of 15 Cases

The potential pitfalls of synovial sarcoma mimicking intraneural ganglion cyst: A case report and literature review

INTRODUCTION AND IMPORTANCE

Synovial sarcoma is a rare soft tissue sarcoma (STS) that accounts for 5-10 % of all STS. Synovial sarcoma of the peripheral nerve is very rare, with only 26 cases reported in the literature. Hence, this case report describes an unusual presentation of synovial sarcoma mimicking intraneural ganglion cysts and a literature review.

PRESENTATION OF CASE

We describe a 36-year-old female who presented to our clinic complaining of left leg pain for six years. MRI was done, which revealed a cystic lesion. With an impression of intraneural ganglion cyst versus nerve sheath tumor of the common peroneal nerve. The patient underwent exploration surgery and mass excision. The mass was sent for histopathology following excision, where the results indicated monophasic synovial sarcoma. An additional surgery, an epineurectomy of the common peroneal nerve and tumor bed excision, was followed by adjuvant chemotherapy with a Doxorubicin-based regimen. Following surgery, our patient's neurological symptoms improved.

CLINICAL DISCUSSION

The mainstay of treatment in synovial sarcoma is surgical excision with a Doxorubicin-based regimen of chemotherapy and/or radiotherapy based on tumor characteristics. Tumors smaller than 5 cm in MRI usually show homogenous enhancement and can be mistaken for benign tumors. Hence, a biopsy should be done before surgery to avoid misdiagnosis.

CONCLUSION

Even though it is extremely rare, synovial sarcoma of the lower extremity should be considered when a painful swelling of the lower leg is associated with a long duration of symptoms. Such lesions are best managed by surgical excision and postoperative chemotherapy.

Monophasic synovial sarcoma mimicking schwannoma: a case report of a rare peripheral nerve tumor and literature review

INTRODUCTION

Synovial sarcomas occurring as primary nerve tumors (SSPN) are rare and only 69 cases of SSPNs are reported in literature. Despite the little data available, SSPNs differ from other SSs in some distinctive aspects such as epidemiology, location, and early onset of symptoms. SSPN are consequently underdiagnosed and easily mistaken for benign or malignant peripheral nerve sheath tumors (PNST). Therefore, cytogenetic or molecular testing becomes essential in order to make a correct diagnosis. This article deals with an extremely rare case of monophasic SSPN of the posterior cords of the right brachial plexus. To our knowledge, this is only the tenth case of intraneural synovial sarcoma involving the brachial plexus.

CASE PRESENTATION

We report the case of a 64-year-old man, who came to our attention due to a slow-growing painful right axillary neoformation, approximately 25 mm in size. The patient did not show any neurological impairments. Ultrasonography and constrast MRI showed a heterogeneous mass arising from the posterior cord of the right brachial plexus, resembling a schwannoma. The patient underwent total resection of tumor and capsule. Histologically, a diagnosis of monophasic synovial sarcoma was made based on histologic features and the immunohistochemical profile.

CONCLUSIONS

We report a rare primary synovial sarcoma of the brachial plexus. Given its rarity, the diagnosis may be challenging and requires a core biopsy or the surgical specimen to permit immune-molecular analysis. Margin-free surgery is the mainstay of curative treatment, while chemo- or radiotherapy may have a role in advanced or margin-positive neoplasms.

Primary Gastric Synovial Sarcoma in a Child: A Case Report and Review of the Literature

Synovial sarcoma is a mesenchymal neoplasm that shows a specific t(X;18) translocation that leads to the formation of SS18-SSX gene fusions and is most commonly seen in soft tissues of the extremity. The gastrointestinal tract is a very rare site of involvement. We report a case of primary gastric synovial sarcoma in a 13-year-old male child. Synovial sarcoma should be included in the differential diagnosis when spindle cell neoplasms are encountered in the stomach. A high degree of suspicion, followed by the necessary immunohistochemistry and molecular studies, is required to make an accurate diagnosis.

Synovial Sarcoma of the Nerve-Clinical and Pathological Features: Case Series and Systematic Review

BACKGROUND

Synovial sarcoma of the nerve is a rare entity with several cases and case series reported in the literature. Despite an improved understanding of the biology, the clinical course is difficult to predict.

OBJECTIVE

To compile a series of patients with synovial sarcoma of the peripheral nerve (SSPN) and assess clinical and pathological factors and their contribution to survival and recurrence.

METHODS

Cases from 2 institutions collected in patients undergoing surgical intervention for SSPN. Systematic review including PubMed and Scopus databases were searched for related articles published from 1970 to December 2018. Eligibility criteria: (1) case reports or case series reporting on SSPN, (2) clinical course and/or pathological features of the tumor reported, and (3) articles published in English.

RESULTS

From patients treated at our institutions (13) the average follow-up period was 3.2 yr. Tumor recurrence was seen in 4 cases and death in 3. Systematic review of the literature yielded 44 additional cases with an average follow-up period of 3.6 yr. From pooled data, there were 10 recurrences and 7 deaths (20% and 14%, respectively). Adjuvant treatment used in 62.5% of cases. Immunohistochemical markers used in diagnosis varied widely; the most common are the following: Epithelial membrane antigen (EMA), cytokeratin, vimentin, cluster of differentiation (CD34), and transducin-like enhancer of split 1 (TLE1). Statistical analysis illustrated tumor size and use of chemotherapy to be negative predictors of survival. No other factors, clinically or from pathologist review, were correlated with recurrence or survival.

CONCLUSION

By combining cases from our institution with historical data and performing statistical analysis we show correlation between tumor size and death.

The Imaging Spectrum of Synovial Sarcomas: A Pictorial Review From a Single-Centre Tertiary Referral Institution

Synovial sarcomas are malignant soft-tissue tumors that typically affect young patients. They can arise from nearly anywhere in the body, most commonly the extremities, head and neck, and thorax. The imaging features are highly variable and depend on the anatomic origin. Most lesions present as large aggressive heterogeneous masses containing hemorrhagic and cystic foci, often with calcification. However, up to one-third of lesions have commonly benign features and can appear homogeneously solid or cystic. Especially in these cases, their innocuous imaging and clinical presentation can lead to delayed diagnosis. Therefore, knowledge of the imaging spectrum is crucial to ensuring adequate follow-up or timely pathologic sampling. We reviewed 30 pathologically proven cases in various anatomic sites from our institution to illustrate these characteristics.

Primary Intraosseous Synovial Sarcoma with Molecular Confirmation: Expanding and Clarifying the Spectrum of This Rare Neoplasm

Synovial sarcoma is a well-known malignant tumor usually originating within deep soft tissues of the lower extremities of adolescents and young adults. Rare radiologically confirmed examples of primary bone synovial sarcoma have been documented, generally in isolated case reports. Herein, we report two cases of primary intraosseous synovial sarcoma, with molecular confirmation, involving the left humerus of a 45-year-old female and the right fourth metatarsal bone in a 36-year-old male. Additionally, we clarify the spectrum of primary intraosseous synovial sarcoma by separately analyzing reported cases with radiographic confirmation of bone origin and molecular support for the diagnosis. There are clinicopathologic differences between those tumors with documented molecular confirmation and those lacking such confirmation, specifically regarding their anatomic distribution (p < 0.0001). Regarding the radiology of our two cases, the humeral lesion appeared almost entirely intramedullary without soft tissue extension; the midfoot lesion demonstrated a destructive, metatarsal-centered bone lesion, initially thought clinically to represent primary bone osteosarcoma. The diagnoses of monophasic synovial sarcoma were rendered via core needle biopsies, with molecular FISH confirmation of SYT gene rearrangement. Clinical follow-up data was only available for the female patient with the primary humeral lesion, who underwent surgical resection, with no local recurrence or distant metastasis at 7 months postsurgery. To our knowledge, these are the first reported examples of molecularly confirmed, primary intraosseous synovial sarcomas of the humerus and metatarsal bones. Primary intraosseous synovial sarcomas with molecular confirmation differ clinically from those lacking it; however, the demographic features and metastatic potential appear similar to primary soft tissue synovial sarcoma.

Intracranial synovial sarcoma: A clinical, radiological and pathological study of 16 cases

INTRODUCTION

Synovial sarcoma (SS) is a tumor of unknown origin and is extremely rare in the central nervous system. Most studies on intracranial SS included only one or two cases. To better understand the disease, we review a series of primary intracranial SS.

METHOD AND MATERIALS

16 primary intracranial SS in Tiantan Hospital during 2008-2017 were included. The clinical characteristics, including radiological and histological examination, operative records, and prognoses were reviewed.

RESULT

The case series included nine male and seven female patients with an average age of 23.8 years. Radiological results showed that the supratentorial region (81.25%) was the most common site of the brain involved. All patients were misdiagnosed as non-SS tumors. Gross total resection (GTR) was achieved in 12 cases (75.0%), and subtotal resection (STR) was achieved in 4 cases. All cases showed the characteristic SYT-SSX fusion gene, as detected by RT-PCR. The mean progression-free survival time (PFS) was 10.0 months and the mean overall survival time (OS) was 15.5 months. Multivariate analysis revealed that GTR and postoperative adjuvant radiotherapy were independent factors for PFS (HR = 6.143, 95% CI = 1.491-25.312; P = 0.012, HR = 6.143, 95% CI = 1.491-25.312; P = 0.012 respectively) and OS (HR = 9.000, 95% CI = 1.627-49.773; P = 0.012, HR = 0.017, 95% CI = 0.001-0.213; P = 0.002 respectively).

CONCLUSION

Intracranial SS were more frequently observed in the supratentorial region and in young patients without sex predilection. We recommend adjuvant radiation regardless of the extent of resection. More patients and longer follow-up periods were needed to further elucidate the biological features of intracranial SS.

Bone and Soft Tissue Tumors About the Foot and Ankle

The foot and ankle delicately balance the need for support of the weight of the human body, with the need for flexibility. Palpable masses about the foot and ankle, therefore, are most commonly related to trauma or mechanical instability. Non-neoplastic causes, such as ganglion cysts and callus, therefore, predominate. However, the radiologist must be aware of the imaging appearance of less common benign and malignant neoplasms that can involve the foot and ankle.