Tonsillar synovial sarcoma, unusual anatomical location: case report and literature review

Abstract

Background

Synovial sarcoma is a rare soft tissue malignancy, occasionally found in the head and neck region. The diagnosis necessitates a multidisciplinary approach involving the clinical presentation, proper imaging studies and histological confirmation, with molecular testing for definitive identification. Treatment entails surgical resection with adjuvant therapies as needed.

Case presentation

A 33-year-old male patient presented with globus sensation concomitant with right-sided neck swelling. He was clinically found to have right tonsil enlargement with posterior extension. Therefore, he underwent right tonsillectomy with pharyngoplasty. Histopathological examination revealed a biphasic tumor consistent with synovial sarcoma, confirmed by immunohistochemistry and fluorescence in situ hybridization.

Conclusions

Tonsillar synovial sarcoma represents a diagnostic challenge, requiring a high index of suspicion and comprehensive evaluation. With only twenty previously published cases documented in the literature, awareness of this rare presentation is crucial for prompt diagnosis and appropriate management. Collaboration among multidisciplinary healthcare teams and ongoing research efforts are essential for optimizing diagnostic accuracy, treatment efficacy, and patient outcomes in this rare malignancy.

Background

Synovial sarcoma (SS) is a rare soft tissue sarcoma of uncertain differentiation. It comprises 5–10% of all soft tissue sarcomas. It commonly occurs in adolescents and young adults, with a mean age of onset of 39 years, and equal incidence among males and females [1]. SS is most frequently encountered in the para-articular regions of the extremities. However, it has been demonstrated in the literature to involve unusual locations, including the head and neck region [2, 3]. The single most common site of Head and neck synovial sarcoma (HNSS) is the hypopharynx [2, 4].

Tonsillar SS is extremely rare, with only twenty well-documented cases published in the literature. In this case report, we present a case of a 33-year-old male patient found to have primary synovial sarcoma arising in the right palatine tonsil, confirmed molecularly by Fluorescence in situ hybridization (FISH).

Case presentation

A previously healthy 33-year-old male presented with complaints of globus sensation, dysphagia, odynophagia, snoring, and frequent choking. Upon examination, the patient was found to have right-sided neck swelling. Fiberoptic laryngoscopy revealed posterior extension of the right tonsil, prompting a decision to perform a right tonsillectomy with pharyngoplasty. Intraoperatively, enlargement of the right tonsil with posterior extension was noted, and excision was performed. Specimens were collected and sent for histopathological evaluation. No pre-operative radiological assessment was conducted.

Fig. 1

The gross appearance of the right tonsil showing tan homogenous cut surface (A). H&E sections of a biphasic lesion with prominent glandular structures admixed with closely packed spindled cells showing focal palisading with intervening ectatic vascular spaces (B-E)

Gross examination of the specimens revealed two containers labeled as “right tonsillar masses,” each fixed in 10% buffered formalin. The specimens consisted of multiple fragments of brown firm tissue measuring 7.0 × 4.0 × 1.5 cm and 4.5 × 4.0 × 1.0 cm in aggregate, respectively. Sectioning demonstrated tan homogeneous cut surfaces [Fig. 1 (A)].

Histopathological examination revealed a biphasic tumor comprising epithelial and spindle cell components. The epithelial component exhibited gland-like spaces lined by atypical cells with a high nuclear/cytoplasmic ratio, displaying pleomorphic ovoid to elongated hyperchromatic nuclei. The spindled cells appeared monomorphic with scant amphophilic cytoplasm and hyperchromatic nuclei, arranged in a fascicular pattern with minimal intervening stroma. Myxoid degeneration and ectatic stag-horn-like vascular spaces were observed in the background. Occasional mitotic figures were appreciated, and no evidence of necrosis was noted within the examined sections [Fig. 1 (B-E)].

Fig. 2

Immunohistochemical staining showing positivity for Cytokeratin 7 (A) and Epithelial membrane antigen (EMA) (B) highlighting the epithelial component. BCL-2 (C) and CD99 (D) immunohistochemical markers are positive in the spindle cell component

Immunohistochemistry revealed positivity for epithelial markers, including Epithelial membrane antigen (EMA), Pancytokeratin, and Cytokeratin 7. Spindle cell areas demonstrated positivity for BCL-2, and CD99 immunohistochemical markers [Fig. 2 (A-D)].

Fluorescence in situ hybridization (FISH) analysis successfully detected the characteristic t(X;18)(p11.2;q11.2) translocation, confirming the diagnosis of synovial sarcoma [Fig. 3].

Based on the comprehensive evaluation of histopathological, immunohistochemical, and molecular findings, a diagnosis of biphasic synovial sarcoma was established. French Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) tumor grade is 2 (Tumor differentiation 3, Mitotic count 1, Tumor necrosis 0).

Following the surgical intervention, the patient was subsequently transferred to a specialized cancer center to receive comprehensive treatment. Radiological assessment conducted at the center revealed no evidence of distant metastases. As per our correspondence with the center, it was elucidated that the patient underwent external beam radiation therapy (EBRT) targeting the post-tonsillectomy tumor bed, with a dosage regimen of 60 Gy delivered in 30 fractions, accompanied by sequential boosts. Notably, the patient has exhibited favorable progress in the ensuing months post-operation; however, persistent complaints regarding altered taste sensation have been reported.

Fig. 3

Fluorescence in situ hybridization (FISH) analysis showing SYT gene rearrangement

Discussion

Synovial sarcoma (SS) is a rare malignant connective tissue tumor, comprising 5–10% of soft tissue sarcomas [5]. Despite their name, these soft tissue tumors do not originate from synovial cells. They predominantly manifest in the extremities, with approximately 80–95% of cases observed there, while the intrathoracic, intraabdominal and head and neck regions are less frequently affected [2, 3, 6,7,8].

Synovial sarcoma of the head and neck (HNSS) is recognized as a rare and aggressive malignancy. The hypopharynx stands out as the predominant anatomical site affected by HNSS [2, 4]. Morphologically, SS manifests in three distinct histologic variants: monophasic, biphasic, and poorly differentiated [5].

In the head and neck, SS can manifest in various anatomical sites, including the oral cavity, pharynx, larynx, parotid gland, and other soft tissue structures [8]. The most frequent presenting complaint is a painless mass or swelling, which may also be associated with dysphagia, changes in the quality of voice and dyspnea depending on the specific anatomical site of the lesion [2].

The diagnosis of SS involves a combination of imaging modalities such as MRI or CT scans to assess tumor extent and a biopsy to confirm the histopathological diagnosis. The hallmark of synovial sarcoma is the presence of a characteristic chromosomal translocation, resulting in the fusion of the SYT gene on chromosome 18 with either the SSX1, SSX2, or SSX4 gene on chromosome X. Detection of this fusion gene through molecular genetic testing aids in confirming the diagnosis [7].

In the existing literature, there have been reports of more than 150 documented cases of synovial sarcoma occurring within the head and neck region. Notably, among these cases, only a limited subset—specifically twenty (20) instances—were identified within the tonsils. Within this subset, nineteen cases (19/20) were classified as primary synovial sarcomas originating from the tonsils, while one case (1/20) was recognized as metastatic in nature. All cases were encountered in male patients. Predominantly, fourteen cases (14/20) manifested in the right tonsil, with five occurrences (5/20) documented in the left tonsil. The laterality of one case (1/20) remained unspecified. Histologically, sixteen out of twenty (16/20) cases exhibited a biphasic morphology, characterized by the presence of both epithelial and spindle cell components. Four out of twenty (4/20) cases displayed a monophasic pattern. Only five of the reported twenty cases of tonsillar SS were confirmed by cytogenetic analysis (t(X;18) (p11.2; q11.2)). Only three cases (3/20) revealed a poorly differentiated component. (Table 1) [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25].

Table 1 Review of previous tonsillar SS cases

In the management of head and neck synovial sarcoma (HNSS), a comprehensive approach incorporating surgery, radiation therapy, and/or chemotherapy is typically employed. Surgery, often considered the mainstay of treatment for synovial sarcoma (SS), aims for complete tumor excision with negative margins. In certain cases, cervical lymph node dissection may be necessary. Radiotherapy has demonstrated effectiveness in controlling the disease by targeting cancer cells and reducing the risk of local recurrence. However, the efficacy of chemotherapy remains controversial and is usually reserved for larger, high-grade tumors or cases with metastatic disease. Commonly used chemotherapeutic agents include doxorubicin and ifosfamide. Neoadjuvant therapy may be administered before surgery to shrink tumors, while adjuvant therapy is employed after surgery to target any remaining cancer cells. Additionally, emerging targeted therapies, such as tyrosine kinase inhibitors and immunotherapy, show promise in treating refractory cases. Due to limited data on tonsillar synovial sarcoma, there is currently no standard protocol for its treatment. Therefore, treatment strategies should be tailored to individual tumor characteristics and patient well-being [2, 20, 25,26,27].

The prognosis of head and neck synovial sarcoma (HNSS) depends on tumor characteristics and treatment efficacy. Tumor size, histological subtype, metastatic status, surgical margin extent, patient demographics, and tumor biology play a crucial role in determining long-term outcomes. Accordingly, collaboration among multidisciplinary healthcare teams, along with ongoing clinical research, is essential to enhance patient outcomes, validate prognostic factors, optimize treatment efficacy, and minimize adverse effects [28, 29].

The reporting of a tonsillar synovial sarcoma case holds significant importance in medical literature, providing insights into this rare form of malignancy. These contributions serve as essential educational source for healthcare professionals, aiding in the accurate diagnosis and effective management of this condition. Through meticulous documentation of diagnostic hurdles, treatment methodologies, and patient outcomes, such reports enrich our understanding of the disease’s progression, prognosis, and therapeutic interventions, guiding evidence-based clinical decision-making, and ultimately enhancing patient care.

Conclusions

In summary, synovial sarcoma of the head and neck in general and in the tonsils in particular represents a diagnostic challenge and requires high index of suspicion. This rare malignancy underscores the importance of thorough clinical evaluation, imaging studies, and histopathological confirmation for accurate diagnosis. Treatment should be tailored to individual patient and particular tumor characteristics to optimize outcomes. Despite limited data on tonsillar synovial sarcoma, collaborative efforts among multidisciplinary healthcare teams and ongoing research are crucial for enhancing diagnostic accuracy, treatment efficacy, and patient care in this rare disease entity.