cyst. casesThyroglossal duct cyst (TGDC) is the most common non-odontogenic cyst in the neck. It is a lesion mainly deteded in childhood but which may elude detedion until adulthood.

108

CASE REPORT

Thyrolllossal duct cyst. A clinicopatholollical study of five casesAsma'a Abdulrahman AI-Ekrish: BDS Omar Saad AI-Jonaidel:* MSc

Hezekiah A. Mosadomi:** DMD, DABOMP

(~~) Y-"Jk; Ji~l,yp) ;Jpl If"r-' C) u..u y If"r-' )Jw,'y\\f" r-' C)

AL-EKRISHET AL.

Histolo~ically, non-specific connedive tissuewith muscle tissue in transverse and lon~itudinalsections was seen. An elliptical cysticconfi~uration was present with a double row ofcuboidal epithelial linin~ with a focus ofintraluminal hyperplasia. Two foci of lymphoida~~re~ates were seen. The histopatholo~icdia~nosis was consistent with the clinicaldia~nosis ofTGOC

One year later, the cyst recurred as adischar~in~ sinus from the submental wound.Another operation was performed, this timeincludin~ the resection of a trad up to the base ofthe ton~ue alon~ with the middle of the body ofthe hyoid bone.

The histolo~y of this second specimen showednon-specific skeletal muscles in different sedions,fat tissue, and mucous acini which colledivelywere not dia~nostic but convincin~ly consistentwith a clinically dia~nosed TGOC

The patient was followed up for approximatelytwo months post-sur~ery and no recurrence wasdetected.

Case 2

A 14-year-old male presented with a swellin~ ofthe neck to the left of the midline with one yearduration which was ~rowin~ in size. Lesion waspainless. Clinical examination revealed acompressible mass 2 x 2 cm in size. The mass didnot move upwards with de~lutition and ton~ueprotrusion. Oifferential dia~noses were TGOCandbranchial cleft cyst.

Fine needle aspiration smear showedproteinous material mixed with abundantsquamous epithelial cells. No atypia was seen. Thehistolo~ic dia~nosis was "compatible with aretention cyst."

CT section with contrast enhancementrevealed an oval well-defined, well-encapsulatedlow-density lesion with density much lower thanthe surroundin~ muscles and bein~ mostly that ofa viscous fluid. The lesion was approximately 2 cmin size.

The cyst was sur~ically removed and followedupwards to the hyoid bone and part of it wasremoved with the cyst (Schlan~e procedure).

The histopatholo~y report supported thedia~nosis ofTGOC

Casel

A 24-year-old female presented with a painless

109

swellin~ hi~h alon~ the midline of the neck. It hadbeen present for six months and dischar~in~ pusfor four days prior to presentin~ at the clinic (Fi~.1). The lesion was clinically dia~nosed as aTGOC

OPG and a views did not show the lesion andultrasound ima~in~ could only display a non-specific cystic lesion.

Under ~eneral anesthesia, the fistula wasexcised and a Sistrunk operation was performed.

Histolo~ically, the sections showed fibrousconnective tissue with duct-like strudures lined bysquamous and pseudo-stratified ciliatedepithelium with moderate to severe lymphocyticinfiltration around the duds. The linin~ showedpresence of mucous secretin~ cells. Thehistopatholo~ic dia~nosis was TGOC

At four months follow-up, no si~ns ofrecurrence could be detected.

FI~. 1. Twenty-four-year old female presented with sinus highalong the midline of four days duration; swelling was of sixmonths duration (Case 3).

case 4

A 75-year-old male presented with a swellin~ inthe left submandibular re~ion of seven yearsduration which was ~radually increasin~ in size.Ourin~ the previous month, the swellin~ becamesli~htlytender. Clinical examination revealed a leftsubmandibular mass, 10 x 8 cm in diameter thatwas compressible (Fi~. 2). Re~ionallymph nodesand the overlyin~ skin were normal. The thyroid~Iand was found to be normal. Intraorally, the

Saudi Dental Journal. Vol. 15, No. 2, May, August 2003

110

lesion was found to be plun~in~ into the floor ofthe mouth sli~htly raisin~ the ton~ue. The teethwere found to be decayed. Medical history wasunremarkable.

Fi~. 2. Swelling in submandibular region of seven years'duration seen in 75-year-old male (Case 4). Clinical and aexamination suggested a cystic tumor of submandibular gland.Intra-operatively. it was found to be separated from the glandand attached to the hyoid bone. suggesting a TGDC.

Orthopantomo~raph and PA views of themandible showed si~ns of resorption at theinferior border of the left body of mandible.Furthermore, the left side of the mandible showeda diffuse area of reduced radio-opacity whencompared with the ri~ht side possibly due to adecrease in the bucco-Iin~ual width caused bythinnin~ of the cortical plates.

A smear of the fine needle aspiration of cystcontents showed proteinaceous material mixedwith abundant a~~re~ates of pi~ment-Iadenmacropha~es, PMNs and Iymphocytes. A fairnumber of crystals were seen. No atypical cellswere seen. The dia~nosis was a subacutelyinflammed retention cyst.

A G scan of the neck and mandible showed ahypodense, well-defined mostly encapsulatedlesion ovoid in shape and inferior to the mostinferior part of the mandible anteriorly and mostlyat the level of the hyoid bone. The density of thelesion was lower than that of the surroundin~

Saudi Dental Journal, Vol. 15, No. 2, May - August 2003

THYROGLOSSALDUG aST

muscles and was homo~enous with no evidenceof calcified material. No enlar~ed lymph nodeswere seen. Thinnin~ of the mandibular bonecould be deteded on both the buccal and lin~ualaspeds. The G report ~ave a dia~nosis of cystictumor of the left submandibular ~Iand.

The patient was operated on for removal of thelesion which was found intra-operatively to beseparated from the submandibular (which wasfound to be hypertrophic) and sublingual ~Iands.The cyst was dissected superiorly from the floor ofthe mouth and inferiorly found to be attached tothe hyoid bone. It was removed in one piece withthe central portion of the hyoid bone. Intra- andpost-operative dia~noses were TGDC.

Histolo~ically, the lesion was described as acyst lined by squamous epithelium and pseudo-stratified co~umnar epithelium with hyalinizationof the connective tissue wall. Focal cholesterolclefts were seen. Multinucleated ~iant cells werealso present. The connective tissue was wellvascularized with small and medium sized bloodvessels. The histopatholo~ic dia~nosis wasconsistent with TGDC.

The patient was lost for follow-up afterdischar~e.

case 5

A 30-year-old woman presented with a swellin~in the neck to the ri~ht of the midline between thehyoid bone and thyroid cartila~e which rose withton~ue protrusion and de~lutition. It had beenpresent for more than one year and fluctuated insize. The clinical dia~nosis was TGDC.

Fine needle aspiration of the contents of thelesion yielded 3.0 ml of brown colored fluid.Microscopically, the smear showed pi~ment ladenmacropha~es and Iymphocytes. The appearancewas compatible with TGDC.

A thyroid scan six days later with TC99revealednormal shape, size, and location of both thyroidlobes with homo~enous fixation of the tracer. Theswellin~ appeared hi~h up in the middle of theneck and did not show any tracer uptake and hadnearly disappeared after aspiration for the FNA.The scan dia~nosis stated that the lesion wascompatible with TGDC.

Throu~h a transverse neck incision, the strapmuscles and the cystic lesion were explored. Thebody of the hyoid bone was removed alon~ withthe cyst and a core of tissue was removed upwardsreachin~ the base of the ton~ue,

Histolo~y of the resected lesion was that of acyst lined by pseudostratified ciliated columnar

AL-EKRISHET AL.

epithelium with thyroid follicles around the cyst(Fi~. 3).The dia~nosiswasTGDC.

FIQ. 3. Photomicrograph of lesion excised from 30 year oldfemale (Case 5) (H&E 40x). Thyroid follicles clearly seenconfirming previous diagnosis ofTGDC.

Discussion

The small number of cases of TGDC whichpresented to our department is not surprisin~since this lesion is most often discovered inchildhood and thus normally presents to pediatricdepartments. To our knowled~e, the onlypreviously published report from Saudi Arabia wason 33 cases seen over a ten-year period in patientswith an a~e ran~e of one to 35 years.? Apart fromthe fewer number of cases seen in ourmaxillofacial sur~ery department, the clinicalpidure in most of our cases deviated from theclassic clinical description.

Most cases of TGDC become apparent durin~the first decade of life. 1,8,9Althou~h it is re~arded

111

as a lesion of the youn~, TGDC may beencountered in adults, as found in our Cases 3 and5, and in the elderly, as was found in Case 4. In areview of 381 case ofTGDC, Brown and Judd (1961),showed 28% of their patients to be above 40 yearsof a~e.10 Telander and Dean (1977) found lessthan 10%to occur in patients over 60."

Althou~h the cyst is classically described as amidline lesion, it may be situated lateral to themidline in 10-20% of cases.s This ran~e has beensupported by the result of a review of 300 cases ofTGDC by Solomon and Ran~ecroft (1984) whofound the lesion lateral to the midline in 16% ofcases.12 In our five patients, three cysts weresituated lateral to the midline, two to the left andone to the ri~ht. Deviation from the midline maybe due to inflammation causin~ a more eccentricposition 12or to branchin~ remnants.13

The vertical position of the lesion could alsovary. It has been found to be intralin~ual in 2.1% ofcases, suprahyoidal in 24.1%, thyrohyoidal in60.9%, and suprasternal in 12.9%.1The lesions intwo of our cases (40%) were suprahyoidal whilethree (60%) were thyrohyoidal. We encounteredno suprasternal lesions; however, it should bereco~nized that this does not necessarily indicatethat they do not occur since lesions in this re~ionare more likely to present to ~eneral sur~erydepartments.

Most TGDCs are asymptomatic but could besecondarily infeded in an upper respiratory tractinfection.14 Allard (1982) reported thatinflammation was the most often mentionedinitiatin~ stimulus.1 Inflammation may lead to arapid increase in size, cellulitis and even abscessformation.1S,16 Fistulization onto skin, as seen intwo of our patients, occurs in approximately one-third of patients. 1,17Fistulas may form as a result ofspontaneous dischar~e followin~ inflammation ofa cyst, or after sur~ical intervention, or rarely ascon~enital fistulas.12 When a sinus related to aTGDC is present, it is mostly in the midline andstressed with ton~ue protrusion. It may showdischar~e ofcysticfluid or pus. If there isasinus orrecurrent infedion related to a cervical lesion,whether in the midline or laterally placed, a TGDCshould be suspeded. If a thickened tract from thelesion to the hyoid could be felt by palpation, thedia~nosis may be confirmed. Tracin~ the sinus (byinjedion of a radiopaque dye and radio~raphy)may lead to the foramen caecumY

The differential dia~nosis of TGDC includesbranchial cleft and dermoid cysts. Branchial cleftcysts are usually described as located lateral to themidline and are not expected to be affeded by

Saudi Dental Journal. Vol. 15. No. 2, May - August 2003

112

ton~ue protrusion and swallowin~. Dischar~in~fistulas and aspirates of branchial cleft cysts aresimilar in appearance to those ofTGDCs. However,differentiation between the two lesions may beachieved by sinus trackin~. Injection of aradiopaque dye into fistulas caused by branchialcleft cysts leads to the tonsillar fossa. Of interest tonote is that a case was seen in our department inwhich a lesion was found in the midline of theneck of a four-year-old ~irl and was clinicallydiagnosed as TGDC. However, histopatholo~icalexamination of the wall of the lesion revealednumerous lymphoid follicles indicatin~ that it was,in fact, a branchial cleft cyst. This hi~hlights thediagnostic challen~e ofswellin~s in the neck.

Dermoid cysts, like TGDCs, are ~enerallyconsidered to be midline lesions but may bedifferentiated from TGDC by their consistency.They have a dou~hy consistency and the morecomplex the histolo~ic composition, the fi rmer thelesions are clinically. Dermoid cysts can, likeTGDCs, present with a dischar~in~ sinus wheninfected; but when caused by the former, the sinusis more superficial and firmer. Furthermore, theaspirate of a dermoid cysts is a yellow cheesysubstance which is very easily distin~uished fromthe fluid expeded from TGDCs.

a scans can be a useful aid in the dia~nosis ofTGDCswith re~ard to the position and relationshipto adjacent anatomical strudures. The typicalappearance of a TGDC in a a scan is a wellcircumscribed low-density lesion with peripheralrim enhancement.18 a scannin~, however, is notuseful in differentiatin~ between different typesof cysts.

Delineatin~ the different types of cysts isimportant since the mana~ement of TGDCsrequires not just simple excision but rather aSistrunk operation which requires excision of thecyst, the central portion of the hyoid bone, andremoval of a core of muscles up to the base of theton~ue. Failure to do so, as in Case 1 in our report,may lead to recurrence of the cyst.

The histolo~ic appearance of a TGDC is a cystlined by respiratory epithelium with thyroid tissue,mucous ~Iands, and small patches of lymphoidtissue variably present in the connedive tissuewall.19 The presence of thyroid tissue in theconnective tissue wall of the cyst is consideredpatho~nomonic of TGDC, however not allspecimens display such tissue. Accordin~ to theliterature review by Allard (1982), the frequency ofcasesthat showed thyroid tissue ran~ed from 1.5%to 45%1,12,20. Our findin~s, which showed afrequency of 17%, fall within this ran~e. However,

Saudi Dental Journal. Vol. 15. No. 2, May, August 2003

THYROGLOSSALDUa CYST

serially sedioned lesions may reveal a hi~herfrequency of thyroid follicles. 21,22

Conclusions

Dia~nosis of swellin~s in the head and neckre~ion could present a challen~e to the clinician,especially when the clinical presentation of thelesion is inconsistent with the classical description.Most cases of TGDCsmanifest in early childhoodand thus present to pediatric departments most ofthe time. However, the oral and maxillofacialsur~eon may also encounter such a lesion inadolescents and older patients and therefore mustconsider its variable presentation. Five cases ofthyro~lossal dud cyst treated in our departmentare described with each havin~ a different clinicalpicture. Althou~h the clinical and histolo~icalpresentations of these five cases are not rare, theydo illustrate how varied thyro~lossal dud cysts canbe with resped to patient a~e, anatomic site, orassociated si~ns and symptoms.

Acknowled~ement

We would like to thank Dr. Abdullah AI-Atal,former head of the Maxillofacial Sur~eryDepartm.ent of the Riyadh Medical Complex forprovidin~ the clinical photo~raphs.

References

1. Allard RHB.The thyro~lossal cyst. Head Neck Sur~1982; 5: 134-146.

2. Mont~omery WIN. Sur~ery of the upper respiratorysystem. Philadelphia: Leaand Febi~er, 1973,p. 80.

3. Soucy P,Pennin~ J. The clinical relevance of certainobservations on the histolo~y of the thyro~lossaltrad.J Pedia Sur~ 1984; 19: 506,509.

4. Santia~o W, Rybak LP, Bass RM. Thyro~lossal ductcyst of the ton~ue. JOtolaryn~011985; 14:261-264.

5. Ward GE, Hendrick JW, Chambers RG. Thyro~lossaltrad abnormalities· Cysts and fistulas. Sur~ GyneObstetrics 1949;89: 727-734.

6. Eversole LR. Clinical outline of oral patholo~y:Dia~nosis and treatment. Philadelphia: Lea andFebi~er, 1992 p. 213.

7. AI-Arfaj A. Thyro~lossal dud remnants. Annals SaudiMed 1994; 14: 136-138.

8. Gross RE, Connerly ML. Thyro~lossal cysts andsinuses: A study and report of 198 cases. NewEn~landJ Med 1940;223: 616-624.

9. Sammarco GJ,McKenna J.Thyro~lossal dud cysts inthe elderly. Geriatrics 1970;25: 98-101.

10. Brown PM, Judd ES.Thyro~lossal dud and sinuses:Results of radical (Sistrunk) operation. Am J Sur~1961;102: 494-501.