CongenitalCervicalCysts,SinusesandFistulae
StephanieP.Acierno,MD,MPH,
JohnH.T.Waldhausen,MD*
DepartmentofSurgery,Children’sHospitalandRegionalMedicalCenter,
UniversityofWashingtonSchoolofMedicine,G0035,
4800SandPointWay,NE,Seattle,WA98105,USA
Thyroglossalductanomalies
Thyroglossalductanomaliesarethesecondmostcommonpediatricneckmass,behindadenopathyinfrequency[1].Thyroglossalductremnantsoccurinapproximately7%ofthepopulation,althoughonlyaminorityoftheseiseversymptomatic[1].
Embryology
Thethyroidglandformsfromadiverticulum（medianthyroidanlage）located
betweentheanteriorandposteriormusclecomplexesofthetongueat
week3ofgestation.Astheembryogrows,thediverticulumisdisplacedcaudally
intotheneckandfuseswithcomponentsfromthefourthandfifthbranchialpouches（lateralthyroidanlagen）.Thedescentcontinuesanterior
toorthroughthehyoidbonewiththemediananlageelongatingintothe
thyroglossalduct（Fig.1）[2].Byweeks5to8ofgestation,thethyroglossal
ductobliterates,leavingaproximalremnant,theforamencecum,atthebase
ofthetongueandadistalremnant,thepyramidallobeofthethyroid[1,2].If
theductfailstoobliteratebeforetheformationofthemesodermalanlageof
thehyoidbone,itpersistsasacyst[2].
Clinicalpresentationanddiagnosis
Twothirdsofthyroglossalductanomaliesarediagnosedwithinthefirst
3decadesoflife,withmorethanhalfbeingidentifiedbeforeage10years
[1].Themostcommonpresentationisthatofapainlesscysticneckmass
nearthehyoidboneinthemidline（Figs.2and3）[2].Althoughtheyare
mostcommonlyfoundimmediatelyadjacenttothehyoid（66%）,theycan
alsobelocatedbetweenthetongueandhyoid,betweenthehyoidandpyramidal
lobe,withinthetongue,orwithinthethyroid[2,3].Themassusually
moveswithswallowingorprotrusionofthetongue.Approximatelyone
thirdpresentwithaconcurrentorpriorinfection,whichisthemorecommon
presentationinadults[2,4].Onefourthofpatientspresentwithadraining
sinusthatresultsfromspontaneousdrainageorsurgicaldrainageofan
abscess[2].Thisdrainagecanresultinafoultasteinthemouthifthespontaneous
drainageoccurredbywayoftheforamencecum.Theselesionsalso
fluctuateinsize.Otherrarepresentationscanbesevererespiratorydistress
orsuddeninfantdeathsyndromefromlesionsatthebaseofthetongue,
alateralcysticneckmass,ananteriortonguefistula,orcoexistencewith
branchialanomalies[2].
Thepreoperativeevaluationforapatientwhohasasuspectedthyroglossal
ductcystincludesacompletehistoryandphysicalexamination,preoperative
ultrasound,andascreeningthyroidstimulatinghormone（TSH）level.
Patientswhohavehistory,examinationfindings,orelevatedTSHlevelssuggesting
hypothyroidismorasolidmassshouldundergoscintiscanningto
ruleoutamedianectopicthyroid[2].Whenmedianectopicthyroidispresent,
allofthepatient’sfunctionalthyroidtissuecanbelocatedwithinthe
cyst,anditsremovalwouldrenderthepatientpermanentlydependenton
thyroidreplacement.Themanagementofmedianectopicthyroidiscontroversial.
Someinvestigatorsbelievethesepatientscanbetreatedwithexogenous
thyroidhormonetosuppressthegland,whereasothersadvocatefor
resectionforreasonsthatarediscussedlater[2].Althoughmedianectopic
thyroidonlyoccursin1%to2%ofthyroglossalductcysts,someauthorsadvocateforscintiscansinallpatients[5].
Treatment
Electivesurgicalexcisionisthetreatmentofchoiceforuncomplicated
thyroglossalductcyststopreventinfectionofthecyst.TheSistrunkprocedureisperformed,ratherthansimpleexcision,toreducerecurrence
risk[2].Withthepatientinsupinepositionandtheneckextended,atransverse
incisionismadeoverthemass.Thedissectioniscarrieddowntothe
cyst,thencaudallytoidentifythetracttothepyramidallobe.Ifpresent,
itisexcisedenblocwiththecyst.Thesurgeonthendissectscraniallytoward
thehyoidboneandablockoftissuearoundtheproximaltractisalsoexcised.
Thecentralportionofthehyoidboneisalsoexcisedandthetract
isfurtherdissectedwithacoreoftissuefromthemuscleatthebaseof
thetonguetotheforamencecum（Fig.4）[2].Afterconfirmingadequate
proximaldissectionbypressureonthebaseofthetonguefromthemouth,
thetractisligatedandtransected.Intrathyroidalthyroglossalductcysts
shouldalsoundergoaSistrunkprocedureifthereisatranshyoidalfistulous
tract,butcanbetreatedwithhemi-thyroidectomyifnotractcanbe
identified[3].
Infectedcystsorsinusesarefirstmanagedbyrelievingtheinfection.Thecystsareusuallyinfectedbywayofthemouth,thusthemostcommonorganisms
areHaemophilusinfluenza,Staphylococcusaureus,andStaphylococcus
epidermidis[2].Antibioticsdirectedtowardthoseorganismsshouldbe
started.Needleaspirationmayallowfordecompressionandidentification
oftheorganism.Formalincisionanddrainageshouldbeavoided,ifpossible,
topreventseedingofductalcellsoutsidethecyst,whichincreasesrecurrence
[2].Ifincisionanddrainageisnecessary,theincisionshouldbeplaced
soitcanbecompletelyexcisedwithanellipseatthetimeofdefinitiveresection.
Oncetheinfectionclearsandtheincisionheals,thepatientmayundergo
anelectiveSistrunkprocedure[2].
Ifasolidmassisencounteredduringexcisionofasuspectedthyroglossal
ductcyst,itshouldbesentforfrozensectiontoruleoutamedianectopic
thyroid.Ifthebiopsyreturnsasnormalthyroidtissueandthepatienthas
functionalthyroidtissueinthenormallocation,itshouldbeexcisedbytheSistrunkprocedure[2].Ifthemassispossiblythepatient’sonlyfunctional
thyroidtissue,themanagementbecomescontroversial.Oneoptioninvolves
leavingtheectopicthyroid,eitherinsituorrepositioningitlaterally
belowthestrapmusclesorintotherectusabdominusorquadricepsmuscles.
Thisoptionaimstonotrenderthepatientpermanentlyhypothyroid;however,
mostpatientsstillrequirelong-termthyroidhormonetherapytotreat
hypothyroidismorcontrolthesizeoftheectopicthyroidtissueforcosmetic
orfunctionalreasons.Thisneedforlong-termtherapyandthepossibilityof
malignantdegenerationhaveledsometorecommendexcisionofthemedian
ectopicthyroidregardlessofthepresenceofadditionalthyroidtissue[2].Thyroglossalductcystsarelinedwithductalepitheliumorcontainsolid
thyroidtissue.Lessthan1.0%havemalignanttissue,usuallywell-differentiated
thyroidcarcinoma.Thismalignancyoccursmoreofteninadults,buthas
beenreportedinchildrenasyoungas6yearsold[6].Itisusuallyidentified
incidentallyatthetimeofsurgeryforasuspectedthyroglossalductcyst.Papillary
carcinomaisseenmostoften,althoughalltypesofthyroidcarcinoma
exceptmedullarycarcinomahavebeenreported[2,4].Ifthereisnoevidence
ofcapsularinvasionordistantorregionalmetastasis,theSistrunkprocedure
hasbeenassociatedwitha95%curerate,althoughcarefulfollow-upisnecessary
[2].Otherinvestigatorsrecommendcompletionthyroidectomyregardless
ofcapsularinvasioncitingthebenefitsoffullpathologicexaminationof
thegland,facilitationofradioactiveiodineablation,andincreasedsensitivity
ofradioisotopescreeningforrecurrence[1].Ifcapsularinvasionispresent,
completionthyroidectomy,nodaldissection,andradioiodineablationshouldbepursuedasindicatedbytypeandstageofdisease[2].
RecurrenceofthyroglossalductcystaftercompleteexcisionusingtheSistrunk
procedureisreportedtobe2.6%to5%[1,4].Severalfactorshave
beenidentifiedpredisposingpatientstoincreasedriskforrecurrence.Failure
tocompletelyexcisethecyst（especiallysimpleexcisionalone）canresultin
recurrenceratesof38%to70%[1,4].Inchildrenlessthan2yearsold,intraoperative
cystruptureandpresenceofacutaneouscomponentincreasesthe
riskforrecurrence.Preoperativeorconcurrentinfectionofthecysthasbeen
historicallyreportedasariskfactorbecauseoftheincreaseddifficultyof
completeresection,althougharecentreviewfoundthatpostoperativeinfections
ratherthanpreoperativeinfectionswereassociatedwithincreasedrecurrence
[2,7].Recurrentthyroglossalcystexcisionhasahigherriskfor
recurrence（20%C35%）andrequiresawiderenblocresection[2].先天性颈部囊肿，窦道和瘘管――甲状舌管畸形
甲状舌管畸形是继淋巴结肿大之后第二常见的儿科颈部肿块。人群中约有7%的人存在甲状舌管残留，然而只有少数人会出现临床症状。
胚胎学
甲状腺来源于怀孕三周时，舌前部和后部肌肉之间的一个憩室（甲状腺中基）。随着胚胎发育，该憩室逐渐向尾部移位，进入颈部，并与第四第五腮囊（甲状腺外侧基）融合，并向前下降到达或者穿过舌骨，由此，中基延伸为甲状舌管。孕5到8周时，甲状舌管闭塞，近端在舌根形成盲孔，远端形成甲状腺的锥体叶。假如该管道在舌骨的中胚层原基形成之前不能闭锁，则只能以囊肿的形式存在。
临床表现和诊断
2/3的甲状舌管畸形可在30岁之前被诊断，其中有一半在十岁以前就可以发现。其最常见的临床表现为颈部正中接近舌骨的部位出现无痛性的囊性肿块。尽管大多数囊肿紧邻舌骨（66%），亦有部分位于舌体和舌骨之间，舌骨和甲状腺锥体叶之间，舌骨体内，或状腺内。肿块通常随吞咽或伸舌而移动。约三分之一在发现之前或发现当时合并有感染，这在成人中是最常见的表现。1/4的人由于脓肿自发破溃或者外科引流手术而形成窦道。若这种自发破溃从舌盲孔端引流到口腔中可有恶臭感。这些囊肿大小不尽相等。其他罕见的临床表现有由于舌根的囊肿导致的严重呼吸窘迫或者婴儿猝死综合征，颈侧区的肿块，舌前囊肿，或与腮裂畸形并存。
拟诊为甲状舌管囊肿的病人的术前评估包括完整的病史和体检，术前超声检查和TSH水平的测定。病史，体检和TSH测定提示有甲状腺功能减退或实质性病变的病人应行闪烁扫描以排除异位甲状腺。假如是异位甲状腺，病人所有有功能的甲状腺组织有可能都在囊肿内，如果把囊肿摘除会导致病人永久依赖甲状腺激素替代治疗。颈中部异位甲状腺的治疗尚存在争议。一些研究者认为可以通过给予外源性甲状腺激素抑制腺体的生长，另外一些则提倡切除，原因见后续讨论。尽管颈中部异位甲状腺在甲状舌管囊肿中仅占1%――2%，还是有人认为所有的病人都应该行闪烁扫描检查。
治疗
对于不复杂的甲状舌管囊肿可以选择性的进行外科手术切除以预防感染。为了减少复发率，我们用了Sistrunk术式而不是一般的切除。病人取仰卧颈伸位，在肿块上方做横切口，向下分离到囊肿，然后向尾部探查瘘管的走向直到锥体叶。如有瘘管存在则和囊肿一起整块切除。然后向头侧朝舌骨分离并把瘘管近端周围的组织切除。舌骨中段和瘘管从舌根到舌盲孔的部分以及周围的组织也一起切除。当确定近端切除了足够的组织并从口中给与舌根足够的加压之后，将瘘管结扎横断。甲状腺内的甲舌囊肿如果有经舌骨的瘘管，也应行sistrunk术式，但如果找不到管道，可以行单侧甲状腺切除术。
有感染的囊肿或窦道应先控制感染。最常见的是经口腔感染。常见的致病菌为流感嗜血杆菌，金黄色葡萄球菌和表皮葡萄球菌，应针对性使用抗生素。可以针刺抽脓减压并采集标本化验。可能的话应避免切开引流，以免瘘管上皮细胞散播增加复发可能。假如不得不切开引流，则切口应该在合适的部位且大小适当，以使得最终切除的时候能够从该切口将肿块整个完整取出。一旦感染清除且切口愈合，则可以进行选择性的sistrunk术式。
假如在切除中遇到实质性肿块，应该送冰冻以排除异位甲状腺组织。假如冰冻病理证实是正常的甲状腺组织，而该病人在正常位置的甲状腺又有功能，则继续进行sistrunk手术。假如该肿块是病人唯一有功能的甲状腺组织，处理方式上则存在争议。一种认为是保留该异位甲状腺，不管是让它继续在原处还是复位到带状肌下或者腹直肌或者四头肌内。该观点是为了避免病人发生永久的甲状腺机能减退；然而，很多病人仍然需要长期服用甲状腺激素来治疗甲低，或者是出于美容或者功能上的原因服用激素来控制异位甲状腺的大小。这种长期的激素依赖以及恶变的可能使一些人提倡，无论有没有其他甲状腺组织存在，都要切除异位甲状腺。
甲舌囊肿里面布满了导管上皮细胞或者包含有实质性的甲状腺组织。少于0.1％者含有恶性组织，通常是高分化的甲状腺癌。恶性者多发于成人，但6岁的小儿亦有报道。通常是在做甲状舌管囊肿的手术中偶然碰到。乳头状腺癌是最常见的，尽管除了髓样癌之外的所有类型的甲状腺癌都有过报道。假如没有包膜侵犯或者远处或局部转移的迹象，sistrunk手术的治愈率可达95％，但术后要密切随访。其他研究者认为不管有没有包膜侵犯均应行全甲状腺切除术，因为可以对腺体进行完整的病理学检查，有助于放射性碘的治疗，且可以提高放射性同位素筛查有无复发时的敏感性。假如有包膜侵犯，则应根据病理类型和分期进行甲状腺完全切除术、颈清扫、放射性碘治疗。
据报道，行sistrunk手术后甲舌囊肿的复发率为2.6％－5％。有几个因素已经被证明可以增加病人复发的风险。囊肿切除不完全（特别是单一的切除）者复发率为38％-70％。小于2岁的幼儿中，术中囊肿破裂以及有表皮样成分存在可以增加复发率。有报道说之前或当时合并感染者复发的风险亦增高，因为术中完全切除干净的难度增加。而最近又有人发现术后感染比术前感染更能增加复发的风险。复发再次手术的甲舌囊肿再复发的可能显著增加（20%C35%），需要更大范围的整块切除。OtolaryngologyClinicofNorthAmerica40（2007）161C176
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