teratomas of the neck in adults are extremely rare . the tumors of the head and neck account for 5% of all benign and malignant germ cell tumors and for 6% of all teratomas , where the most common sites of involvement are the soft tissue of the neck , thyroid , superficial facial structures , oral cavity , nasopharynx , and orbit ( 1 , 2 ) . we report a case of primary malignant thyroid teratoma in a 31-yr - old female . to our knowledge , this is the first case of malignant teratoma with a primitive neuroectodermal tumor component in the thyroid in korea . a 31-yr - old woman presented to our clinic with a two - month history of a fast growing non - tender mass in the neck . no pertinent past medical illness or family history was present . on physical examination , a large hard and fixed mass the computed tomography scanning of the neck showed a 7.05.5 cm solid heterogeneous enhancing mass arising in the right lobe of thyroid gland ( fig . 1 ) . it was invading beyond the thyroid gland and extended down to the anterior mediastinum . the f-18-fdg positron emission tomography ( pet ) scan showed a huge hypermetabolic mass in the right thyroid gland with multiple hypermetabolic lesions in the neck and in the prevascular area of mediastinum . fine needle aspiration slides revealed diffusely scattered oval to spindle shaped atypical cells with rare eosinophilic amorphous material suggesting poorly differentiated carcinoma possibly consistent with medullary carcinoma . the tumor was penetrating the thyroid capsule and was invading the adjacent tissue involving the right recurrent laryngeal nerve . the upper portion of the sternum was cut to dissect the inferior portion of right thyroid . the lymph nodes along the chain were removed after the sheaths of the common carotid , and internal jugular vein were opened . the postoperative period was uneventful except transient hypocalcemia . on the third day of operation , the total serum calcium level was 6.7 mg / dl with a ionized calcium level of 0.88 , the mass was occupying most of the right lobe of thyroid gland with a ill - defined border , measuring 7.55.04.7 cm . the cut surface was grayish white , hemorrhagic , and necrotic with focal cystic changes . the microscopic examination showed that the tumor was mainly composed of primitive neuroepithelial tissue with primitive neural tubes and loose myxoid to fibrous immature mesenchymal stroma ( fig . the tumor cells were pleomorphic and partly necrotic with hyperchromatism and frequent mitotic figures ( 4 - 6/10 high power fields ) . metastases were present in 25 of total 58 lymph nodes , where metastatic components were only composed of a primitive neuroepithelial component . the tumor cells were positive for synaptophysin , focally positive for cytokeratin , neurofilament , desmin , and cd99 on immunohistochemical staining . the primitive neuroepithelial component comprised more than 4 in low power magnification fields ( 4 objective with a 10 ocular , using bvx . ) , which thus was categorized as malignant teratoma according to the thompson et al . after she recovered from the surgery , she was placed on an intensive chemotherapy according to the national cancer institute protocol reported by grier et al . she received 14 cycles of chemotherapy consisting of vac ( vincristine 2 mg , doxorubicin 75 mg / m , cyclophosphamide 1,200 mg / m , every 3 weeks ) , alternate with ie ( ifosfamide 1,800 mg / m with mesna , and etoposide 100 mg / m for five days by continuous infusion ) . after the completion of the 10th cycle of chemotherapy , she received external beam radiation therapy ( ebrt ) with a total dose of 55.8 gy , 5 days / week . the treated volume included the thyroid bed , cervical lymph nodes , and upper mediastinum . malignant teratoma of the thyroid in adult was first reported by lurje in 1908 , who described a case of a 53-yr - old woman ( 5 ) . by 1999 , nineteen cases of malignant teratoma of the thyroid had been reported in the medical literature , emphasizing the aggressive clinical course of the disease ( 1 ) . after then , 3 cases have been reported ( 2 , 6 , 7 ) . there were a predominance of primitive neuroepithelial component within mature squamous or glandular epithelial components and mature cartilage in our case . malignant thyroid teratoma is an aggressive tumor , with a short median survival ( median , 8 months ) after surgery without postoperative chemotherapy . the commonly used drugs are the same agents effective in the treatment of germ cell tumors ( 6 , 8 , 9 ) . it usually consists of bleomycin , cisplatin , and etoposide ( bep ) protocol alone or in combination with other agents aimed to treat the sarcomatous component . the most common agents included are vincristine , cyclophosphamide and actinomycin - d ( 2 , 6 ) . chen et al . reported a 32-yr - old woman with malignant thyroid teratoma who underwent a simple lobectomy of the thyroid ( 8) . she received chemotherapy of bep and was still alive without evidence of disease after 6.7 yr . djalilian , et al . reported a 33-yr - old woman with malignant thyroid teratoma who underwent 5 cycles of chemotherapy with vinblastin , ifosfamide , and cisplatin ( 1 ) . after 3 further cycles of carboplatin and etoposide , the patient underwent autologous bone marrow stem cell transplant . she did well with evidence of stable disease in the lungs at 21 months from the diagnosis but died of metastatic teratoma . recently , high - dose chemotherapy in combination with autologous stem cell transplant has been found to be effective in prolonging the survival in some patients with gonadal germ cell tumors ( 10 , 11 ) . treated a malignant teratoma of the thyroid with predominantly neuroepithelial differentiation with surgery alone ( 7 ) . she died after 15 months with metastases to liver , vertebra , paraaortic and paracaval lymph nodes . craver et al . reported a 15-yr - old black girl with a malignant thyroid teratoma with exuberant primitive neuroectodermal tumor components . further chemotherapy included vincristin , actinomycin - d , and cyclophosphamide alternating with ifosfamide and etoposide for six cycles . kushner et al . treated 36 patients with poor - risk primitive neuroectodermal tumor ( 12 ) . the protocol achieved excellent pathological or clinical responses in 34 patients and partial responses in two patients . all six patients with metastatic disease limited to lungs achieved a complete response and did not relapse for the follow - up period of 7 to 36 months . primary thyroid malignant teratoma is rare . for teratomas of other sites with primitive neuroectodermal tumor components , the suggestion is to tailor the chemotherapy regimens known to be effective in the treatment of the transformed histology , after complete surgical resection ( 13 ) . most of chemotherapeutic agents chosen for malignant teratomas of the thyroid have been selected and established for teratomas of other origins ( 10 , 11 ) . therefore , we decided to administer an intensive chemotherapy regimen according to the nci protocol int-0091 ( 4 ) . compared the 49 weeks of standard chemotherapy consisting of doxorubicin , vincristine , cyclophosphamide and dactinomycin to chemotherapy alternating with ifosfamide and etoposide in primitive neuroectodermal tumor ( ewing 's sarcoma ) patients . they concluded that for nonmetastatic patients , the 5-yr disease free survival ( 69% vs. 54% ) and overall survival ( 72% vs. 61% ) were superior in the later group . we used the combination chemotherapy altering with ifosfamide and etoposide for this specific patient of primary malignant teratoma with a primitive neuroectodermal tumor component . some investigators have reported the role of ebrt for residual tumor tissues ( 5 ) . although ebrt has frequently been used , its role in front - line therapy is not clear . we opted for the radiation treatment in this patient in light of the extensiveness of the disease and the residual microscopic disease after the surgery . it is suggested that patients with primary malignant teratoma of the thyroid should be managed according to their major malignant component . the complete surgical excision and extensive chemotherapy are recommended for most patients with primary malignant teratoma ( 1 , 6 ) . as for the exuberant primitive neuroectodermal tumor component in this particular case with an extensive involvement of the surrounding soft tissue and lymph nodes , best clinical outcome could be obtained with intensive multidisciplinary therapies consisting of complete excision , chemotherapy and radiation therapy to the lesion .
teratomas comprise the most common extragonadal germ cell tumors in childhood . 
 most teratomas involving the thyroid are benign and occur in children . 
 however , the adult cases reported are mostly malignant and commonly arise in the thyroid . 
 we report a case of a 31-yr - old female with a huge neck mass . 
 pathologic examination revealed it to be malignant teratoma composed of primitive neuroepithelial tissue with primitive neural tubes and loose myxoid to fibrous immature mesenchymal stroma . 
 the patient underwent extensive evaluation of the thyroid gland with computed tomography ( ct ) scan and positron emission tomography ( pet ) scan , which revealed no evidence of metastatic disease . 
 she underwent total thyroidectomy with bilateral modified radical neck dissection , intensive chemotherapy and radiotherapy . at 22-months of follow - up 
 , the patient has remained euthyroid and showed no evidence of recurrence . 
 this is the first case , to our knowledge , of malignant thyroid teratoma with a exuberant primitive neuroectodermal tumor component in korea .