Primary biphasic synovial sarcoma of tongue in an infant: Report of rare case and review of the literature

Overview

Synovial sarcoma (SS) arising from head and neck region in children is very rare. No case of synovial sarcoma of tongue in an infant has been reported. We report a case of biphasic SS of tongue in 8-months-old female making it the first documented case of English language literature.

Key words:
pediatric oncology, synovial sarcoma, quality of life

INTRODUCTION

Synovial sarcoma is a rare soft tissue sarcoma usually divided into three subtypes: biphasic, monophasic and poorly differentiated SS [1]. It accounts for 8–10% of all human soft tissue malignancies [2]. Synovial sarcoma is rarely detected in infants [3]. The majority of patient present between 15 and 40 years of age, and SS is extremely rare in pediatric patients under 2 years of age. In adults and children, the prognostic features include tumor size >5 cm, site, age, extent of primary surgical resection, invasion into bone or neurovascular structures, and high histological grade [4, 5]. Patients with localized disease have a relatively good prognosis as 5 year overall survival (OS) is 76.9–85% [6, 13].

Here we describe the case of an infant presenting with synovial sarcoma of tongue, which is to the best of our knowledge the first case reported in the English literature.

CASE REPORT

A female infant was born in term by Caesarean section due to cephalopelvic disproportion. After delivery, the newborn was within normal development limits and did not suffer from any perinatal and postnatal complications. She was well till the age of 7 months when parents noticed small swelling on the right side of her tongue. She had no difficulty in swallowing. Intraoral examination revealed smooth swelling of right side of tongue. There was no lymph node palpable in the neck. Results of routine laboratory tests were within normal limits.

She was seen by dentist and incomplete excision was done with assumption of cystic lesion (Fig. 1). The specimen around 5 mm consisted of glandular structures associated with a cytologically malignant fascicular spindle cell component. On immunohistochemistry, vimentin, bcl-2, EMA and focally for CK, CK7, SMA, CD99 and CD117 were positive. The tumor cells were negative for desmin, GFAP, factor VIII, S100, CD34, p63, HMB45 and myoglobulin. The glands were highlighted by keratin positivity, staining for EMA was positive not only in glands but also in spindle cells and there was diffuse nuclear positivity for TLE-1, confirming synovial sarcoma diagnosis. The Ki-67 proliferation index was approximately 5%.

For metastasis screening, abdominal, thoracic, and brain MRI were done and did not revealed metastatic spread; no lesion was demonstrated in the tongue. The whole body positron emission tomography (PET)/CT scan as well revealed no abnormal FDG avid lesion at the imaged part of the body. The patient underwent a wide local re-excision of the palpable mass under general anesthesia. The postoperative period was uneventful. Histopathological examination of the operative specimen showed macroscopically tissue piece measuring 17 x 12 x 7 mm with tumor size of 3 mm. The final report confirmed previous diagnosis of synovial sarcoma. The covering mucosa was not ulcerated and all surgical margins were free. Molecular study was done later and showed chromosomal abnormality t(X;18) (p11.2;q11.2).

On the basis of these findings, i.e. radical surgery with free margins, no detected metastases, and primary tumor size <5 cm, it was decided not to administer any adjuvant chemotherapy.

MRI at three and four months of follow up showed no radiological evidence of recurrence of tongue lesion and there was no sign of active disease by clinical examination. The patient reached 1 year in complete remission after radical surgery and is doing well at this time.

DISCUSSION

Synovial sarcoma is the most common non-rhabdomyosarcoma soft tissue sarcoma in children [7]. SS is derived from primitive mesenchymal cells, not synovial cells [1]. As mentioned by Weiss and Goldblum, there were a 1 year old child and a 2 year old child among the 345 patients suffering from SS [1]. According to our knowledge, there were only four cases of SS described in term newborns [3] and fewer than 20 patients under 2 years of age described in the literature [8]. Synovial sarcomas in children are commonly located in the lower extremity and extremely rarely (3–5%) arise in head and neck region [9].

There are three histologic subtypes of synovial sarcoma: biphasic, monophasic, and poorly differentiated. Biphasic subtype represents 20–30% of lesions and has a mesenchymal spindle cell component and an epithelial component. Monophasic subtype comprises 50–60% and poorly differentiated subtype covered up to 15–25% of all synovial sarcomas [3, 10]. Most SSs are immunoreactive for cytokeratin, epithelial membrane antigen, bcl-2 protein, and negative for CD34, and many express S100 protein and CD99 (MIC2). Almost 90% of SSs have a specific chromosomal abnormality t(X;18) (p11.2;q11.2), resulting in fusion of either of two variants of the SSX gene with SYT gene. The differential diagnosis can include a wide range of spindled, polygonal or round cell sarcomas [11].

Radiographs may be normal in approximately 50% of cases of SS. But in up to 30% of cases calcification on x-ray or computed tomography can be found. Magnetic resonance (MRI) is the modality of choice to locally stage the tumor but of course imaging findings are not pathognomonic [10]. Regarding our patient, MRI result was negative after previous biopsy which was done on the base of clinical examination only, without imaging studies.

The primary treatment for SS is surgery to remove the entire tumor with clear margins when possible. Radiotherapy may be avoided with no reduction in survival in patients with IRS group I and even IRS group II tumors, especially in those with small tumor size (<5 cm) [13]. SS is known to present intermediate sensitivity to chemotherapy compared to rhabdomyosarcoma, with calculated response rate around 47–50% to front-line Ifosfamide and Doxorubicin based regimens [14]. The 5-year OS rate is 85% in pediatric patients with localized SS from SIOP-MMT trials [13]. Soole et al. [14] described in French multicenter study that children and adolescents with SS relapse have a poor overall prognosis with 5-year OS 42.1%. But Ferrari et al. in Italian study reported different results as 5-year OS 29.7% [15] and showed that patients, in whom relapse was local and occurred later (more than 18 months after initial diagnosis), had a better chance of cure with 10-year OS of 68.6%. Difference between French and Italian results could be related to the more use of radiotherapy in front-line in Italian series (72.7% vs. 43.3%). Further reason could be due to different frequency of primary metastatic relapses between groups (65.9% vs. 27.0%) [14].

In conclusion, we have described a case of synovial sarcoma of tongue in an 8-month-old infant female. Synovial sarcoma can occur nearly anywhere in the body including tongue and in any age including infants. Radical surgical excision is essential for cure and it should be a final treatment option in small lesions even in children including infants.

Abbreviations:

SS – synovial sarcoma; OS – overall survival; MRI – magnetic resonance imaging; PET/CT scan – positron emission tomography/computer tomography

Došlo: 4. 8. 2015

Přijato: 22. 12. 2015

Correspondence to:

Hubert Mottl, MD, Ph.D.

Pediatric Hematology and Oncology Department

NBK Children’s Hospital

Sabah, Kuwait

e-mail: hmottl@hotmail.com