unusual locations ( 15% ) have been reported , notably including the head , neck , and trunk . such locations make the recognition and differential diagnosis more difficult and the surgical treatment more complex because of the proximity of noble anatomic structures . only 4 cases have been reported in the english literature [ 2 , 3 , 4 , 5 ] . here , we report an additional case of primary thyroid svs  the first one treated with a combination of surgery and adjuvant chemo- and radiotherapy  and review the literature . the patient was a 55-year - old caucasian male with a personal medical history of high blood pressure and smoking . in december 2012 , he underwent a cervicothyroid ultrasonography because of a rapidly growing palpable neck mass for 1 month , associated with dysphagia . physical examination revealed a 7-cm , firm , macronodular , fixed , dipping thyroid mass . ultrasonography revealed a 7-cm mass of the left thyroid lobe which was heterogeneous , hypervascularized , and mixed ( solid and liquid ) . biological thyroid tests , including serum tumor markers , were normal . because of suspicion of anaplastic thyroid carcinoma , the left lobe was under tension , ovalized , and enlarged ( more than 12 cm ) and extended from the top of the neck to the superior mediastinum . its mobilization was difficult and led to capsular rupture and effusion of necrotic , hemorrhagic , and gelatinous liquid . because of perioperative rupture and tumor fragmentation , the resection was classified as incomplete ( r2 ) . 1 ) of multiple white - tan tumor fragments ( between 2 and 3.5 cm each ) revealed a dense cellular proliferation composed of ovoid - shaped to frankly spindle - shaped cells , without overt nuclear atypia , and disposed in a fascicular pattern . the mitotic index was moderate , inferior to 10 mitoses per 10 high - power fields . a rich vasculature was composed of branching vessels with a staghorn or hemangiopericytoma - like pattern . on immunohistochemistry ( ihc ) , tumor cells stained heterogeneously but strongly for epithelial membrane antigen ( ema ) . they were negative for pan - cytokeratin ( ae1-ae3 ) , cd34 ( only staining the rich vasculature ) , desmin , h - caldesmon , ps100 , hmb-45 , and mdm2 antibodies . the diagnosis of monophasic svs was suspected , and slides were sent to our expert institution for confirmation . molecular analysis , performed on formalin - fixed paraffin - embedded tissue by fluorescent in situ hybridization ( fish ) , showed a syt gene rearrangement , highly consistent with the diagnosis of a monophasic svs , fibrous type . the histologic grade was 2 in the fnclcc system ( differentiation 3 , mitosis count 1 , and necrosis 0 ) . only 15 days after surgery , clinical examination detected a local disease evolution with palpation of a 4-cm neck mass , associated with dysphagia and pain . whole - body computed tomography ( ct ) scan revealed a 5-cm mass , in contact with the frontal parts of the left primitive carotid artery and internal jugular vein and the thyroid cartilage . cervical magnetic resonance imaging ( mri ) confirmed a 4.2-cm mass in contact with large vessels and likely invasion of the paralaryngeal fat tissue above the thyroid cartilage ( fig . because of immediate postoperative relapse , local extension , and known relative chemosensitivity of svs , we delivered primary chemotherapy combining doxorubicin and ifosfamide , before possible surgery . after 3 cycles , mri and ct scan showed tumor size stabilization , with a small volume reduction ( 4  3  5.5 vs. 4.5  3  6 cm ) , associated with extension of necrosis within the mass ( 60 vs. 20% before chemotherapy ) . mri also showed a decrease in fat invasion and contact with the large vessels , whereas perichondrium invasion of the thyroid cartilage remained stable . after the last cycle , mri and ct scan showed small tumor reduction ( 4  2.5  4.5 vs. 4  3  5.5 cm ) with further extension of tumor necrosis and improvement of tumor contact with the internal carotid artery and the internal jugular vein , without a resectability margin relative to the thyroid cartilage ( fig . after discussion with the patient , it was decided to perform conservative surgery , without laryngectomy . tumor resection was done including resection of the previous cutaneous scar , prelaryngeal muscles , thyroid cartilage perichondrium , superior horn of the thyroid cartilage , and left longer horn of the hyoid bone . an additional resection was performed in the thyroidectomy area with removal of fat and lymph nodes in the upper mediastinum . , the left inferior laryngeal nerve was resected , but all other vascular and nervous elements could be preserved ( fig . unfortunately , the resection margins ( left cricothyroid muscle ) were microscopically involved by tumor cells . thyroid sarcomas , frequently reported before the 20th century , are in fact very rare . in 1940 , ewing reported that most of the published cases were mainly anaplastic carcinomas . from that day , cases of originally thyroid sarcomas have been reported , including kaposi sarcoma , leiomyosarcoma , and radiation - induced sarcoma , but they are very rare in incidence . thyroid svs is extremely rare with to our knowledge only 5 cases , including the present case , reported in the english literature [ 2 , 3 , 4 , 5 ] . the median age of patients at the time of diagnosis is 55 years ( range 1572 ) , which is older than the median age reported in other locations where svs typically affects adolescents and young adults . no specific risk factor has been identified . all cases were clinically symptomatic , the major complaint for all patients being a firm mass rapidly growing in the anterior neck , suggestive of anaplastic thyroid carcinoma . no case with asthenia , anorexia , loss of weight , or thyroid dysfunction has been reported . radiological imaging is useful for the diagnosis and staging of thyroid tumors . generally , the first exam is ultrasonography , which shows a heterogeneous nodule , with malignancy criteria such as important size or hypervascularization . ct and/or mri allow the localization of the tumor in the thyroid gland and a better appreciation of the local extension before surgery . in our case , ct scan and mri showed a voluminous local relapse and contact with the large vessels and the thyroid cartilage . a whole - body scan can also find distant metastatic sites , as observed in 1 patient   with multiple bilateral lung nodular lesions only 2 weeks after diagnosis , in agreement with the high lung metastatic potential of sarcomas . when svs arises in an unusual site such as the thyroid , recognition and differential diagnosis are difficult , as demonstrated by the 5 cases reported , for which diagnosis was based on pathological , ihc , and molecular analyses of the operative specimen . preoperative diagnosis based on fine - needle aspiration biopsy is very difficult : in the 2 cases where fine - needle aspiration biopsy was done , the suggested diagnosis was medullary carcinoma   and benign follicular lesion . histologically , our case showed only a spindle cell component without any identifiable epithelial structures , and thus was classified as a monophasic svs , fibrous type . previous cases located in the thyroid included 2 biphasic tumors with follicular - like structures , and 2 others with a monophasic spindle cell proliferation . two cases displayed ( at least focally ) a hemangiopericytomatous vasculature as in our case , whereas 1 had calcifications . the suggestive ihc staining for ema in the spindle cell population has been found in 3 cases [ 3 , 4 ] including ours . although morphological and ihc features could be highly unequivocal , the diagnosis of svs needs to be confirmed by molecular analysis , detecting the syt - ssx gene fusion ( virtually found in all svs ) by real - time reverse transcriptase polymerase chain reaction ( rt - pcr ) or fish , using frozen or paraffin - embedded tissues . all 5 reported cases show the specific fusion , except 1 in which molecular testing has not been performed . such analysis is feasible on tumor biopsy and should be performed in the case of diagnostic doubt since the preoperative diagnosis of sarcoma is fundamental . data on the prognosis of thyroid svs are very limited with only 3 cases , including ours , informative regarding the follow - up after initial surgery . two patients experienced both lung and local relapses at 0.5 months   and 18 months   and died 3 and 36 months , respectively , after surgery . our patient experienced immediate local relapse after primary surgery , without any metastatic relapse after a 10-month follow - up . overall , these data suggest that prognosis of thyroid svs is very unfavorable , more unfavorable than other locations , potentially due to the uncommon form of presentation , rapid growth , delay in diagnosis , and difficulty in complete excision . like for any soft - tissue sarcoma , the main treatment is margin - free monobloc surgery , and the roles of adjuvant chemotherapy and radiotherapy are unclear . in all 5 cases reported , initial surgery was total thyroidectomy , associated with partial resection of neighbor organs in 2 cases [ 2 , 3 ] and with cervical lymph node dissection in 2 cases [ 3 , 4 ] . unfortunately , the large tumor size and the proximity and invasion of neighbor noble organs and vessels made wide margin - free surgical resection very difficult , with perioperative tumor rupture in 2 cases . as usual for sarcomas , lymph node dissection is not recommended unless suspect lymph nodes are detected . given the associated poor prognosis , the high risk for relapse for our patient , both local and metastatic , the relative chemosensitivity of svs , and the evidence of benefit for adjuvant anthracycline - based chemotherapy in men older than 40 years after incomplete surgery of soft - tissue sarcoma , we delivered 6 cycles of doxorubicin - ifosfamide combination therapy before surgery . chemotherapy led to disease stabilization with minor response that authorized secondary surgery . because of microscopically incomplete resection and high risk for local relapse , adjuvant radiotherapy was performed . in conclusion , we report the fifth case of primary svs of the thyroid gland , and the third with a follow - up after diagnosis . as these tumors are exceptional and information about diagnosis , prognosis , and standard treatment is lacking , we think that case reports such as this one may serve as the only reference for clinicians taking care of these patients . radical surgical excision is the best chance for cure , but multimodality treatment deserves to be discussed given the high local and metastatic risks and overall poor prognosis . like svs of other sites , thyroid svs seems responsive to doxorubicin - ifosfamide chemotherapy which should be used preoperatively in the cases where margin - free resection can not be anticipated .
synovial sarcoma ( svs ) of the thyroid gland is exceedingly rare . 
 we report the case of a 55-year - old man with a rapidly growing 7-cm neck mass . because of suspicion of anaplastic thyroid carcinoma , 
 a total thyroidectomy was planned , without preoperative cytology . during surgery , 
 the tumor ruptured , leading to fragmented and incomplete resection . 
 the morphological and immunohistochemical aspects suggested thyroid svs , which was confirmed by fluorescent in situ hybridization ( syt gene rearrangement ) . 
 the patient experienced immediate local relapse in close contact with large vessels and the thyroid cartilage and was referred to our institution . 
 doxorubicin - ifosfamide chemotherapy led to a minor response that authorized secondary conservative surgery . 
 because of microscopically incomplete resection , adjuvant radiotherapy was chosen and is ongoing 10 months after initial surgery . 
 the prognosis of thyroid svs is associated with a high risk for local and metastatic relapses . 
 pretreatment diagnosis is fundamental and may benefit from molecular analysis . 
 margin - free monobloc surgical excision is the best chance for cure , but adjuvant chemotherapy and radiotherapy deserve to be discussed .