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struma testis is a rare entity , and there are only few reports on the malignant transformation of a testicular teratoma to papillary thyroid carcinoma in the literature . in this report , we describe the malignant transformation of struma testis with distant lung metastasis associated with trisomy 17 and a coexisting papillary microcarcinoma in the thyroid .
a 56-year - old man presented after a left orchiectomy for an undescended left testicle .
pathologic examination identified a monodermal teratoma composed of thyroid parenchyma and associated with a 1.7-cm papillary thyroid carcinoma .
total thyroidectomy revealed a 0.5-mm focus of papillary thyroid cancer , and removal of the lung mass confirmed metastatic papillary thyroid cancer .
array - comparative genomic hybridization of both tumors showed trisomy 17 in the struma testes and the lung metastasis .
the patient responded well to radioactive iodine ablation and has no evidence of cancer 3 years later .
to our knowledge , this is the first case of papillary thyroid cancer in struma testes metastatic to the lung .
surgery to remove cancer foci , followed by radioactive iodine ablation , resulted in an excellent response in our patient .
interestingly , trisomy 17 , which has so far been observed only in noninvasive thyroid nodules , was associated with pulmonary metastasis in our patient .
papillary thyroid carcinoma is the most common type of differentiated thyroid carcinoma , which is usually confined to the thyroid and tends to metastasize to regional lymph nodes .
cases identifying thyroid tissue in an ovarian teratoma and struma ovarii are well described in the literature .
it is estimated that thyroid tissue presents in 15% of ovarian teratomas and that it is the dominant tissue , classified as struma ovarii , in 5% of the cases [ 1 , 2 ] .
, we describe a rare case of struma testis characterized by malignant transformation and pulmonary metastasis associated with trisomy 17 , with a coexisting papillary microcarcinoma of the thyroid .
a 56-year - old caucasian male with a history of an undescended left testicle was admitted to a community hospital with right lower quadrant pain .
although he had refused orchiectomy in the past , he consented to it on this admission .
the left testicle was noted to be in the left pelvic sidewall and was resected without complication .
prior to admission , he was asymptomatic and denied weight loss , dysphagia , odynophagia , and voice hoarseness .
he did not have a history of smoking , exposure to radiation , or a family history of thyroid cancer .
the evaluation for testicular tumor markers included normal serum -fetoprotein and normal serum -human chorionic gonadotropin .
lactate dehydrogenase was slightly elevated ( 680 units / l , normal range 313618 ) .
a chest x - ray on the day of admission revealed a well - demarcated 3-cm round density in the lower right perihilar region .
a ct scan of the chest with intravenous contrast showed a well - circumscribed soft tissue mass arising from the inferior right hilar area , with a size of 2.2  2.4  2.7 cm , as well as a 0.7-cm lesion in the right superior hilar area and multiple smaller nodules in the lower lobes of both lungs .
the pathology report identified the testicular tissue as a monodermal teratoma composed of thyroid parenchyma and associated with the development of papillary thyroid carcinoma with a predominantly follicular growth pattern ( fig .
immunoperoxidase stains demonstrated that the neoplastic cells were strongly positive for cytokeratin cam 5.2 and thyroid transcription factor 1 .
-fetoprotein , vimentin , -human chorionic gonadotropin , placental alkaline phosphatase , s100 , cd30 , inhibin , and calretinin stains were negative in the malignant cells . a video - assisted thoracoscopic wedge biopsy of the right lower lobe nodule revealed metastatic papillary thyroid carcinoma . due to concerns about the effectiveness of i-131 ablation in the presence of a right lower lobe mass
the pathology report of all specimens confirmed papillary thyroid cancer , with a maximum tumor size of 2.1 cm in the right lower lung lobe ( fig .
interestingly , the patient had one microscopic focus ( 0.5 mm ) of papillary carcinoma with follicular architecture ( fig .
a pretreatment stimulated ( thyroid - stimulating hormone 95 miu / ml ) whole - body scan using 1.5 mci of i-123 showed a residual uptake in the neck ( 2.5% ) in addition to foci of increased uptake in the lungs bilaterally . at the same time , the serum thyroglobulin ( tg ) level was 16.8 ng / ml , and that of tg antibodies ( tgabs ) < 0.9 iu / ml . to determine
whether the papillary microcarcinomas of the lung and testis have a similar origin , we performed braf and ras ( hras , nras , and kras ) mutational analyses , which were negative , and comparative genomic hybridization ( array - comparative genomic hybridization , a - cgh ) from both the lung and testis revealed trisomy 17 and monosomy x , indicating their common origin ( fig .
the patient was treated with 200 mci of i-131 , and the posttherapy whole - body scan did not show any new areas of increased uptake .
he was started on levothyroxine 175 g daily and did very well clinically and biochemically .
nonstimulated ( thyroid - stimulating hormone 0.111 miu / ml ) tg and tgabs were undetectable .
one year after the i-131 ablation , thyrogen - stimulated tg was < 0.2 ng / ml , with tgabs at < 20 iu / ml ( normal range 0.0020 ) , and a whole - body scan using 1.55 mci of i-123 did not show any iodine concentration areas consistent with metastases .
a ct scan of the neck and chest revealed a decrease in the size of the unresected lung nodules .
we presented a unique case of a metastatic papillary thyroid carcinoma from struma testis and raised the question whether the testicular and lung lesions could be metastases from the papillary thyroid microcarcinoma .
first , normal thyroid tissue was present adjacent to the malignant papillary thyroid component in the teratoma , making it most likely that the teratomatous thyroid tissue underwent malignant transformation .
second , it is generally accepted that papillary microcarcinomas exhibit benign behavior and have an overall excellent prognosis . in fact
, there is an up to 35% incidental prevalence of papillary microcarcinoma at autopsy [ 5 , 6 ] .
furthermore , distant metastases from papillary microcarcinomas are reported to be 0.6% in a large meta - analysis .
the sites of distant metastasis from papillary microcarcinoma included pulmonary , intratracheal , and cervical lymph nodes . however , no cases of papillary microcarcinoma metastasizing below the diaphragm in general , and to the testis specifically , have ever been reported . on the contrary , there is a case report of a malignant metastatic testicular teratoma that was found initially in the thyroid .
furthermore , molecular genetic analysis of the three tumors was performed in order to answer the question of whether the papillary microcarcinoma could have been the primary tumor .
first , braf v600e and ras ( hras , nras , and kras ) mutational analyses were performed and were negative .
the dna extracted from the testis and lung separately was hybridized with normal dna controls onto an a - cgh designed by nimblegen and analyzed using genoglyphix software ( perkin elmer , signature genomics , spokane , wash .
the thyroid microcarcinoma could not be evaluated , because no malignant tissue remained for sampling .
have demonstrated a strong association between isolated trisomy 17 and follicular thyroid nodules , which have nuclear features of papillary thyroid carcinoma , suggesting a link between papillary thyroid carcinoma and trisomy 17 .
however , all nine cases studies were noninvasive . in our case , the a - cgh indicates that the testis and lung have the same genomic profile and are therefore most likely of the same origin ( i.e. teratomatous transformation in the struma testis which metastasized to the lung ) .
the first case was a 65-year - old male who was found to have a cystic structure in the testes described as viable thyroid tissue with areas of complex papillary arrangements .
the second case of malignant struma testis was a 68-year - old euthyroid male with a 5-cm mass in the upper pole of the right testis .
gross and microscopic examination revealed a replacement of testicular parenchyma with a microcystic tumor that had the appearance of normal thyroid tissue with histologically , solid , trabecular , follicular , and papillary areas .
for the first time , we report a case with struma testis that underwent malignant transformation with distant lung metastasis as confirmed by a - cgh , and without regional para - aortic lymph nodes , and a coexisting papillary microcarcinoma in the thyroid .
our approach to the management of this tumor seems to be rewarding as the patient is cancer free 3 years later .
trisomy 17 , which has typically been associated with noninvasive thyroid nodules with features of focal papillary carcinoma changes , was detected in both testicular and pulmonary tissues , confirming the invasive nature of the tumor .
in recent years , increasing focus on the cytogenetic and molecular analysis of tumor cells has allowed a better understanding of thyroid nodules as well as of thyroid cancer .
our case provides evidence of a papillary thyroid cancer in struma testes metastatic to the lung , confirmed by cgh studies .
surgery to remove cancer foci , followed by radioactive iodine ablation , resulted in an excellent response in our patient .
in contrast to previous studies , our case report has shown that trisomy 17 , which has so far been observed only in noninvasive thyroid nodules , was associated with pulmonary metastasis .
the authors declare that there are no conflicts of interest regarding the publication of this paper .
backgroundstruma testis is a rare entity , and there are only few reports on the malignant transformation of a testicular teratoma to papillary thyroid carcinoma in the literature . in this report , we describe the malignant transformation of struma testis with distant lung metastasis associated with trisomy 17 and a coexisting papillary microcarcinoma in the thyroid.case reporta 56-year - old man presented after a left orchiectomy for an undescended left testicle . 
 pathologic examination identified a monodermal teratoma composed of thyroid parenchyma and associated with a 1.7-cm papillary thyroid carcinoma . 
 further evaluation showed a pulmonary mass on a chest ct scan . 
 total thyroidectomy revealed a 0.5-mm focus of papillary thyroid cancer , and removal of the lung mass confirmed metastatic papillary thyroid cancer . 
 array - comparative genomic hybridization of both tumors showed trisomy 17 in the struma testes and the lung metastasis . 
 the patient responded well to radioactive iodine ablation and has no evidence of cancer 3 years later.conclusionto our knowledge , this is the first case of papillary thyroid cancer in struma testes metastatic to the lung . 
 it highlights the difficulties in treating these patients . 
 surgery to remove cancer foci , followed by radioactive iodine ablation , resulted in an excellent response in our patient . 
 interestingly , trisomy 17 , which has so far been observed only in noninvasive thyroid nodules , was associated with pulmonary metastasis in our patient .