polysplenia syndrome ( pss ) , as a subtype of heterotaxy ( asplenia is another ) , is a rare congenital abnormalities usually diagnosed in adults , incidentally . it is initially described by helwig in 1929 and is frequently associated with a wide range of anomalies in various organs . papillary thyroid carcinoma , as a dtc , ordinarily behaves in an indolent manner with good prognosis and long - term survival . distant metastases are only seen in a minority of dtc patients , and the most common site of distant metastasis is the lung , followed by bone . sm and smm from dtc are extremely rare , and they are usually ignored in patients with thyroid cancer . however , the detection of rare distant metastases may have significant impact on the staging , management , and prognosis of the patients . in this case report , we presented an interesting case of pss associated with sm and smm from papillary thyroid carcinoma , in which fdg pet / ct was proved to be valuable in detecting the common and uncommon sites of distant metastases , as well as in depicting the imaging features of pss . to the best of our knowledge , the concurrence of pss , sm , and smm from papillary thyroid carcinoma in the same patient has not been reported previously . an 84-year - old chinese man was admitted with complaints of enlarged masses in bilateral neck , right axillary , and inguinal areas for > 2 months . he also complained of progressive pain on low back , buttock , and legs for nearly 1 month , ambulation dysfunction for nearly 1 week , and urinary incontinence for 3 days . he had no previous history of splenectomy . on physical examination , masses were palpable in bilateral neck , right axillary , and inguinal areas . in the following ultrasonography , an ill - defined mass in the lower pole of the right thyroid lobe with multiple superficial lymphadenopathies in bilateral cervical and inguinal areas , and right axillary area were found , which was highly suggestive of malignancy . biopsy in thyroidal mass and the superficial lymphadenopathies in bilateral neck , right axillary , and inguinal regions were suggested to obtain a definitive histological diagnosis and to exclude other possible malignancies . the histological results of biopsy were consistent with papillary thyroid carcinoma with multiple regional lymph nodes metastases . the patient was then referred to our pet / ct department to further evaluate the situation and search for possible metastatic disease . the patient fasted > 6  h before the tracer injection and received an intravenous injection of 5.55  mbq / kg ( 0.15 mci / kg ) of 18f - fdg , with a maximum of 370  mbq ( 10 mci ) . the blood glucose level was measured immediately at the time of fdg injection and it was 5.7 he was instructed to rest in a quiet dim room without talking during the subsequent 1  h of the fdg uptake phase and was allowed to breathe normally during image acquisition without specific instructions . whole - body pet / ct scan was performed using a pet / ct scanner ( discovery st-16 ; general electric medical systems , milwaukee , wi ) . whole - body f-18 fdg pet / ct images showed an ill - defined hypodensity mass with inhomogeneous intense fdg uptake in the lower pole of right thyroidal lobe ( figure 1 a  c ) , with widespread fdg - avid regions in regional lymph nodes ( figure 1 d k ) , and 3 intense fdg - avid metastases in 2 equal - volume masses in the right upper abdomen ( figure 2 ) . the splenic vessels identified by fdg pet / ct images help us to prove that these 2 right - sided masses are actually multiple spleens ( figure 3 ) . most interestingly , spleen is absent in left upper abdomen , even though this patient had no previous history of splenectomy . pet / ct images also showed the findings of azygos and hemiazygos continuation of the ivc with the absence of the hepatic segment ( figure 4 ) , which was the most frequent finding of vascular anomalies in pss . other imaging findings included a right - sided stomach , a middle line liver , a short pancreas in the absence of body and tail , preduodenal portal vein ( ppv ) , and malrotation of gut ( figures 2 and 4 ) . whole - body f-18 fdg pet / ct imaging on a patient with advanced right papillary thyroid carcinoma . ( a ) 3d - mip images demonstrated widespread increased fdg uptake regions in the body . ( b , c ) selected axial and coronal pet / ct images show that an ill - defined hypodensity mass with inhomogeneous intense fdg uptake in the lower pole of right thyroid lobe ( red arrow ) , measuring 2.0 cm  3.3 cm  4.0  cm , suvmax  =  7.0 . selected pet / ct images also show that extensive markedly fdg - avid sites in regional lymph nodes ( d  g ) , bones ( h , i ) , and skeletal muscles ( j , k ) . imaging findings were highly consistent with advanced thyroid carcinoma with widespread metastases in the body . 3d - mip  =  3-dimensional maximum intensity projection , fdg  =  fluorodeoxyglucose , pet / ct  =  positron emission tomography / computed tomography , suvmax  =  maximum of standard uptake value . pss with multiple splenic metastases was presented . ( a , b ) fdg pet / ct images showed that 2 spleens were located in right abdomen with 3 hypermetabolic foci ( white arrow ) , suggesting splenic metastases . ( a  d ) right - sided stomach ( yellow arrow ) , ppv ( blue arrow ) , a short pancreas in the absence of body and tail ( red arrow ) , a midline liver , and malrotation of gut are also presented . these findings are consistent with the diagnosis of pss with multiple splenic metastases . fdg  =  fluorodeoxyglucose , pet / ct  =  positron emission tomography / computed tomography , ppv  =  preduodenal portal vein , pss  =  polysplenia syndrome . ( a , b ) splenic artery ( red arrow ) and splenic vein ( blue arrow ) are demonstrated in right upper abdomen on fdg pet / ct images . fdg  =  fluorodeoxyglucose , pet / ct  =  positron emission tomography / computed tomography . ( a ) enlarged azygos arch is paralleling the aorta as it drains into the svc ( white arrow ) . ( b ) enlarged hemiazygos drains into the azygos vein at approximately the ninth thoracic vertebral level ( red arrow ) . ( c , d ) enlarged hemiazygos lies on the left side of the aorta ( blue arrow ) . other anomalies including multiple right - sided spleens , right - sided stomach , a short pancreas , ppv , and malrotation of gut were also noted . fdg  =  fluorodeoxyglucose , ivc  =  inferior vena cava , pet / ct  =  positron emission tomography / computed tomography , ppv  =  preduodenal portal vein , svc  =  superior vena cava . although these appearances of pet / ct were not unique to advanced thyroid carcinoma and could also be seen in other malignancies , the histopathological results of biopsy performed before pet / ct imaging excluded other possible malignancy including lymphoma or a second primary malignancy . based on the results of imaging and the histological results of biopsy , a final diagnosis of pss associated with widespread metastases from advanced right papillary thyroid carcinoma was made . due to the advanced stage of the disease which was successfully evaluated by fdg pet / ct and the poor condition of the patient the institutional review board ( pingjin hospital ) approved this work and informed consent was given by patient . polysplenia syndrome ( pss ) , as a subtype of heterotaxy ( asplenia is another ) , is a rare congenital abnormalities . it is generally defined as the presence of multiple spleens and various organ anomalies in the absence of a history of splenectomy . embryonic , genetic , and teratogenic components have all been implicated as causative factors in polysplenia . pss in adults is usually asymptomatic and diagnosed during investigation for unrelated causes . in our case , even though whole - body fdg pet / ct was performed to search possible metastatic disease , it incidentally reveals that multiple right - sided spleens in the absence of spleen in left abdomen , azygos and hemiazygos continuation of the ivc with the absence of the hepatic segment , and other anomalies including right - sided stomach , a short pancreas , middle line liver , ppv , and malrotation of gut , which were highly consistent with the diagnosis of pss . increased awareness of such anatomical anomalies skin melanoma and carcinomas of the breast , lung , ovary , colorectum , and stomach are the most common primary sources of splenic metastases . to our knowledge , only 3 cases of splenic metastases from thyroid carcinoma have been reported to date . the relative rarity of splenic metastases might be explained by the following reasons : ( 1 ) the sharp angle made by the splenic artery , which make it difficult for tumor emboli to enter the spleen ; ( 2 ) the rhythmic contractile nature of the spleen , which squeezes out the tumor embolus and prevent its lodging in the spleen ; ( 3 ) the absence of afferent lymphatic to bring metastatic tumor to the spleen ; and ( 4)antitumor activity due to a high concentration of lymphoid tissue in the spleen . in our case report , considering the potential risk of bleeding , as well as the congential anomalies of spleen illustrated by fdg pet / ct , biopsy in the fdg - avid lesions of the spleens was also not used . therefore , the superior ability of pet / ct in the detection of metastases can also help provide more accessible biopsy sites and help avoid unnecessary invasive diagnostic procedures . it is thought that muscle movement , unsuitable muscle ph , and muscle 's capability to remove the lactic acid produced by tumor contribute to the resistance of skeletal muscles for the metastatic process . it is reported that smm occurred more frequently in patients with carcinoma of lung , kidney , colon , ovary , cervix and uterus , malignant melanoma . however , the reports of smm from dtc are relatively rare . according to a retrospective review , there are only a few reports of skeletal muscle metastases from dtc in previous literatures . in our presented case , multiple intense fdg - uptake metastatic lesions were found in multiple buttock muscles including bilateral piriformis , left erector spinae , and gluteus maximus muscles , as part of multivisceral tumor dissemination in the body . papillary thyroid carcinoma , as a dtc , is frequently characterized by good prognosis and long - term survival . the factors including patient age > 45 years and the advanced tumor stage are indictor of poor prognosis and closely related to the management of the disease . although the common distant sites and regional lymph nodes involvement from dtc usually draw significant concern to us , rare site of metastases are easily ignored because of their scarcity . however , recognizing the patterns of rare metastases has a large effect on clinical decision making and prognosis of dtc patients . because of its high sensitivity and specificity , molecular imaging with 18f - fdg pet / ct imaging is a well - established valuable noninvasive imaging modality for diagnosing , staging , restaging , treatment monitoring assessment , as well as a prognostic indictor of oncological patients , including dtc . as the use of pet / ct imaging become more common in evaluating thyroid carcinomas , sm and smm may not be as rare as we once thought and may increasingly common . in our case , fdg pet / ct can successfully identify widespread regional lymph nodes involvement and common bone metastases , as well as detect the unexpected sm and smm . the detection of these common and unexpected distant metastases from dtc can lead to the modification of treatment strategies , have prognostic implications , provide more accessible biopsy sites , and help avoid invasive procedures . therefore , the patient with thyroid carcinoma should be further investigated with fdg pet / ct to give a more compressive assessment of the disease . our case presented here highlights that whole - body fdg pet / ct imaging can accurately evaluate the situation of dtc by detecting regional lymph node involvement , common and rare distant metastases which are closely related to diagnosis , staging , management , and prognosis of this disease . our case is unique in that pss , sm , and smm from dtc are existed in the same patient .
abstractpolysplenia syndrome ( pss ) is a rare congenital abnormality . 
 metastases to spleen and skeletal muscle from differentiated thyroid cancer ( dtc ) are also extremely rare . 
 our case report aims to present an interesting case of pss associated with splenic metastasis ( sm ) and skeletal muscle metastasis ( smm ) from advanced papillary thyroid carcinoma which was evaluated on fluorodeoxyglucose ( fdg ) positron emission tomography / computed tomography ( pet / ct).an 84-year - old chinese man was admitted with the history of multiple enlarged masses in bilateral neck , right axillary , and inguinal areas for > 2 months . 
 the results of ultrasonography examination were highly suggestive of malignancy . 
 the histological results of the following biopsy were consistent with papillary thyroid carcinoma with involvement of multiple regional lymph nodes . 
 he was referred for an fdg pet / ct imaging to evaluate the situation.fdg pet / ct showed that an intense fdg - avid thyroid mass with widespread regional lymph node involvement and distant metastases in the body . 
 unexpected sites of metastases were detected in the spleens and skeletal muscles . 
 most interestingly , fdg pet / ct imaging also described the typical imaging findings of pss including the 2 right - sided spleens , azygos and hemiazygos continuation of inferior vena cava ( ivc ) , right - sided stomach , middle line liver , a short pancreas , preduodenal portal vein ( ppv ) , and malrotation of gut.whole body fdg pet / ct imaging can accurately evaluate the situation of dtc by detecting regional lymph node involvement , common and rare sites of distant metastases which are closely related to staging , management , and prognosis of this disease . 
 whole - body fdg pet / ct is also valuable in demonstrating the typical imaging features of pss .