Synovial sarcoma is a rare but distinct soft tissue neoplasm, most commonly occurring in para-articular regions of the extremities of young adults and also occurring in the head and neck region. To the best of our knowledge, only one case of primary synovial sarcoma of the thyroid has been previously reported. Here, we report a 15-yr-old man who had a chief complaint of a palpable neck mass. The neck computed tomography revealed a relatively well-demarcated solid mass in the left thyroid gland. After fine needle aspiration cytology, total thyroidectomy and lymph node dissection were performed. Grossly, the mass was covered by the same capsule as the thyroid gland, measuring 6X5X5 cm in dimensions and weighing 78 gm. The cut surface showed a well demarcated, lobulated, grayish tan, and rubbery solid tumor. Histologically, this tumor was a biphasic synovial sarcoma. Immunohistochemical, ultrastructural, genetic studies, and cytologic findings were all consistent with synovial sarcoma. When synovial sarcomas arise in this unusual site, recognition and differential diagnosis become more difficult. The differential diagnosis of a spindle epithelial tumor with thymus-like differentiation is very difficult due to their similar clinical, histological, and immunohistochemical features. Ultrastructural and cytogenetic studies for synovial sarcoma are necessary to establish a definitive diagnosis.
Adolescent ; Diagnosis, Differential ; Humans ; Immunohistochemistry ; Keratins/metabolism ; Male ; Microscopy, Electron, Transmission ; Sarcoma, Synovial/diagnosis/metabolism/*pathology ; Thyroid Neoplasms/diagnosis/metabolism/*pathology ; Vimentin/metabolism

Adult ; Diagnosis, Differential ; Follow-Up Studies ; Humans ; Knee Joint ; Male ; Mucin-1 ; metabolism ; Neurilemmoma ; metabolism ; pathology ; surgery ; S100 Proteins ; metabolism ; Sarcoma, Synovial ; metabolism ; pathology ; Sweat Glands

Adamantinoma ; diagnostic imaging ; metabolism ; pathology ; surgery ; Adult ; Diagnosis, Differential ; Female ; Femur ; Follow-Up Studies ; Humans ; Humerus ; Ilium ; Keratins ; metabolism ; Male ; Middle Aged ; Mucin-1 ; metabolism ; Retrospective Studies ; Sarcoma, Ewing ; pathology ; Sarcoma, Synovial ; pathology ; Tibia ; Tomography, X-Ray Computed ; Young Adult

Adolescent ; Antigens, CD34 ; metabolism ; Bone Neoplasms ; diagnostic imaging ; metabolism ; pathology ; Chondrosarcoma, Mesenchymal ; metabolism ; pathology ; Diagnosis, Differential ; Hemangiopericytoma ; diagnostic imaging ; metabolism ; pathology ; Humans ; Male ; Platelet Endothelial Cell Adhesion Molecule-1 ; metabolism ; Sarcoma, Synovial ; metabolism ; pathology ; Tomography, X-Ray Computed ; Vimentin ; metabolism

Adult ; Angiomyolipoma ; pathology ; Antigens, CD34 ; metabolism ; Diagnosis, Differential ; Female ; Hemangiopericytoma ; pathology ; Humans ; Kidney Neoplasms ; metabolism ; pathology ; surgery ; Nephrectomy ; Sarcoma, Synovial ; pathology ; Solitary Fibrous Tumors ; metabolism ; pathology ; surgery ; Vimentin ; metabolism

12E7 Antigen ; Antigens, CD ; metabolism ; Cell Adhesion Molecules ; metabolism ; Diagnosis, Differential ; Fibrosarcoma ; metabolism ; pathology ; Heart Neoplasms ; genetics ; metabolism ; pathology ; surgery ; Humans ; Male ; Mesothelioma ; genetics ; metabolism ; pathology ; Middle Aged ; Mucin-1 ; metabolism ; Oncogene Proteins, Fusion ; metabolism ; Pericardiectomy ; Pericardium ; pathology ; Sarcoma ; metabolism ; pathology ; Sarcoma, Synovial ; genetics ; metabolism ; pathology ; surgery ; Translocation, Genetic ; Vimentin ; metabolism

12E7 Antigen ; Adolescent ; Adult ; Antigens, CD ; metabolism ; Biomarkers, Tumor ; metabolism ; Brain Neoplasms ; secondary ; Cell Adhesion Molecules ; metabolism ; Child ; Child, Preschool ; Diagnosis, Differential ; Extremities ; Female ; Follow-Up Studies ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Infant ; Ki-67 Antigen ; metabolism ; Male ; Neuroectodermal Tumors, Primitive ; metabolism ; pathology ; Oncogene Proteins, Fusion ; metabolism ; Repressor Proteins ; metabolism ; Sarcoma, Ewing ; metabolism ; pathology ; Sarcoma, Synovial ; diagnosis ; metabolism ; pathology ; surgery ; Soft Tissue Neoplasms ; diagnosis ; metabolism ; pathology ; surgery ; Vimentin ; metabolism ; Young Adult

Objective: To investigate the clinicopathological features, immunophenotype, molecular features and differential diagnosis of primary synovial sarcoma of the lung (PSSL). Methods: Twelve cases of PSSL were collected at Henan Provincial People's Hospital, during May 2010 and April 2021, and their clinicopathological parameters were summarized. SS18-SSX, H3K27Me3, and SOX2 were added to the original immunomarkers to evaluate their diagnostic value for PSSL. Results: The age of 12 patients when diagnosed ranged from 32 to 75 years (mean of 50 years). There were 7 males and 5 females, 2 left lung cases and 10 right lung cases. Of the 6 patients who underwent surgical resection, five cases were confined to lung tissue (T1), one case had mediastinal invasion (T3), two cases had regional lymph node metastasis (N1), and none had distal metastasis. Microscopically, 11 cases showed monophasic spindle cell type and one case showed biphasic type composed of mainly epithelial cells consisting of cuboidal to columnar cells with glandular and cribriform structures. It was difficult to make the diagnosis by using the biopsy specimens. Immunohistochemistry (IHC) showed CKpan expression in 8 of 12 cases; EMA expression in 11 of 12 case; TLE1 expression in 8 of 12 cases; S-100 protein expression in two of 12 cases; various expression of bcl-2 and vimentin in 12 cases, but no expression of SOX10 and CD34 in all the cases. The Ki-67 index was 15%-30%. The expression of SS18-SSX fusion antibody was diffusely and strongly positive in all 12 cases. SOX2 was partially or diffusely expressed in 8 of 12 cases, with strong expression in the epithelial component. H3K27Me3 was absent in 3 of 12 cases. SS18 gene translocation was confirmed by fluorescence in situ hybridization (FISH) test in all 12 samples. Six cases underwent surgery and postoperative chemotherapy, while the other six cases had chemotherapy alone. Ten patients were followed up after 9-114 months, with an average of 41 months and a median of 26 months. Five patients survived and five died of the disease within two years. Conclusions: PSSL is rare and has a broad morphological spectrum. IHC and molecular tests are needed for definitive diagnosis. Compared with current commonly used IHC markers, SS18-SSX fusion antibody has better sensitivity to PSSL, which could be used as an alternative for FISH, reverse transcription-polymerase chain reaction or next generation sequencing in the diagnosis of PSSL.
Male ; Female ; Humans ; Adult ; Middle Aged ; Aged ; Biomarkers, Tumor/analysis* ; Sarcoma, Synovial/diagnosis* ; In Situ Hybridization, Fluorescence ; Histones/genetics* ; Proto-Oncogene Proteins/metabolism* ; Oncogene Proteins, Fusion/genetics* ; Repressor Proteins/metabolism* ; Lung/pathology* ; Lung Neoplasms

OBJECTIVETo assess the diagnostic values of immunohistochemistry and SYT-SSX fusion gene detection for synovial sarcoma.

METHODSBased on clinical features, histological and immunohistochemical profiles, 195 cases of tumors were divided into three diagnostic categories: definitive synovial sarcoma, probable synovial sarcoma and possible synovial sarcoma. RT-PCR Detection of the SYT-SSX fusion gene was performed using paraffin embedded tissue samples. Comparison between RT-PCR and immunohistochemistry results was carried out and their diagnostic value was evaluated.

RESULTSThere were 62 (31.8%) definite synovial sarcomas, 49 (25.1%) probable synovial sarcomas and 84 cases (43.1%) possible synovial sarcomas. SYT-SSX fusion gene was detected in 140 (78.2%) cases overall, including 94.7% (54/57) definite synovial sarcomas, 86.0% (37/43) probable synovial sarcomas and 62.0% (49/79) possible synovial sarcomas. In tumors in the certain and probable synovial sarcoma categories, the positive rates of epithelial membrane antigen (EMA) were significantly higher in the SYT-SSX positive cases than SYT-SSX-negative cases (P = 0.022, P = 0.010, respectively). EMA was positively correlated with the presence of SYT-SSX (r(s) = 0.431, P = 0.001, r(s) = 0.463, P = 0.002, respectively). However, such a correlation was not seen in cytokeratin (CK), vimentin or S-100 protein immunostains (P > 0.05). In tumors of possible synovial sarcoma category, there were no significant differences of CK, EMA, vimentin or S-100 protein between SYT-SSX-positive and SYT-SSX-negative tumors.

CONCLUSIONSSYT-SSX fusion gene detection is not needed when the conventional approaches are diagnostic. EMA positivity has a similar diagnostic value to that of SYT-SSX by RT-PCR for tumors in the probable synovial sarcoma category. However, detection of SYT-SSX is very important for diagnosis of the tumors in the category of possible synovial sarcoma.

Adolescent ; Adult ; Aged ; Biomarkers, Tumor ; metabolism ; Child ; Child, Preschool ; Female ; Humans ; Immunohistochemistry ; Keratins ; metabolism ; Male ; Middle Aged ; Mucin-1 ; metabolism ; Oncogene Proteins, Fusion ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; S100 Proteins ; metabolism ; Sarcoma, Synovial ; diagnosis ; metabolism ; pathology ; Soft Tissue Neoplasms ; diagnosis ; metabolism ; pathology ; Vimentin ; metabolism ; Young Adult

Adenocarcinoma ; metabolism ; pathology ; Adult ; Combined Modality Therapy ; Diagnosis, Differential ; Follow-Up Studies ; Humans ; Keratins ; metabolism ; Lung Neoplasms ; secondary ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; Prostate-Specific Antigen ; metabolism ; Prostatectomy ; Prostatic Neoplasms ; metabolism ; pathology ; secondary ; surgery ; Sarcoma, Synovial ; metabolism ; pathology ; surgery ; Vimentin ; metabolism