Embryogenesis of enterocystomas-enteric duplication cysts of the tongue

Embryogenesis of enterocystomas-enteric duplication cysts of the tongue ./ill I,ipselt, BM, Phi!,” .-lnthon>~ L. Sparttott. Bedford Put-k and ,Vorfh Adrlaidc, Amfrrrlio I)tl’t\\K ,\NfI

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Enteric duplication cysts of the tongue are unusual lesions that may be confused with dermoid cysts, hemangiomas, llngual thyroid remnants, ranulas. and cystic hygromas Two cases of lingua; enteric duplications are reported In a 5-year-old boy and a 4-month-old boy. In the first case the cyst was lined by gastric-type epithelium. and in the second by colontc-type epithelium. Theories of pathogenesis of enteric duplications Include development from small epithehal tncluslons trapped during fusion of primordial tissues. from lncamplete coalescence c.A Iai‘unas that form between epithelial cells of the solid core of the developing gut. trom persistence of epithelial buds within the wall of the bowel, or from nests of trapped entodermal cells. However each of these theories presents problems with respect to lingual enteric cysts, as possible trapping of epithelium by fustng primordia does not explain the presence of heterotopic mucosa, and the tongue does not develop In the same manner as the hollow viscera. It becomes apparent therefore that enteric duplication cysts are a heterogeneous group of lesions that share some morphologic features, but perhaps not the same pathogenesis. IOKAI

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nteric duplications may be multiple and found anywhere throughout the gastrointestinal tract. I‘ronl the mouth to the anus. These spherical. tubular, or divert&lx lesions of developmental origin appear to recapitulate the architecture 01‘ the normal gxtrointestinal tract. Bl, fur the majorit! .II‘C rclatcd Ii) the small intestine with only 0.3’~ rcportcd 1111h1 tongue. I-’ This article descrihc\ t\\t! I:;I‘;o (II’ lingtrxi enteric duplications diagnosed in ~~hildhood :~nd tlix cusses theories of possible pathogcncsI>

bra\\ n discharge l.ronl ;I jinx\ opening on the dor\um ol‘thc tip ol’his ionpue. tlis parent\ had noted th:lt ;I \m;111 qstic blister h:ld ;rppr:lrcd on the dorsum of’his tongue during the iIr\t 2 >cars of’ hir lii‘z. This had subsequently dis~tppeared. hut ;I GnuI opening had developed. Although it had contin)1:111! oo/t~i the: l\rov ni\h Iluid. c:nly recently had the ho> lc:irncti 10 i’\prclhc contcnt5 81 will.

CASE 1 Clinical Features Much to his parent.5 anno\ancc. learned

the unusual

and Lrntisocial

Cb5scar-old IIO! hati heh;lvior 01‘ squirting ,I

Pathologic

Findings

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Fig. 1. Sinogram demonstrates deeply situated lingual enteric cyst in Case I.

Fig. 2. A, Nonkeratinizing stratified squamous epithelium overlying glandular epithelium from Case I. (Hematoxylin-eosin stain; original magnification x200.) B, Complex gastric-type epithelium also present lining enteric cyst in Case I. (Hematoxylin-eosin stain; original magnification x200.) CASE 2 Clinical

Features

A 4-month-old boy had been noted to have a swelling of his tongue at approximately 6 weeks of age that was not growing or hampering feeding. He was admitted to the hospital for its surgical removal. Examination revealed a mass of 10 mm in diameter completely buried in the substance of the tongue at the junction of the anterior two thirds and posterior one third. The tu-

mor was described at surgery as being solid, cystic, well-demarcated, but adherent to the adjacent tissues. It ruptured during surgery and exuded greenish-white mucus material. The excision was considered to be complete and the tongue incision was sutured closed. Recovery was unremarkable. Pathologic

Findings

Macroscopically the cyst lay in fibrous tissue and consisted of an irregular cavity that contained green-white

Fig. 3. A, Whole mount 01’lingual entcric cyst Ironi (‘ase 1. (Ilenlalo\~Iin-co~in stain: original rna:ln~~~stain: origcation ~7.) B, Colonic type epithelium lining lingual enteric cyst in (‘ax ?. (Hematosylin-eosin inal magnification

X200.)

mucoid material. Microscopic examination showed that tbt: cyst was lined by large bowel-type mucos;~ that consisted 01’ tubular glands embedded in ;I lamina propria (t’ig. 3). l‘bc epithelial cells were of simple columnar type, and man! were distended by mucin globules. A few Paneth cells and neuroendocrine-like cells were noted at the base 01 some 01 the crypts, Underlying the mucosa there was a variably developed muscle layer that in some xeab could he been to bc arranged in two layers. recapitulating the circular :tnd longitudinal components seen in the muscularis propria ol’thc intestine. (The pathologic features 01‘ this case have been briefly reported previously. )’ DISCUSSION The differential pediatric maid

diagnosis

age-group

cyst,

01‘ ;I tongue

includes

neurofbroma,

maser in the

dermoid

cyst.

hemangioma.

cpidcr-

Iymphangi-

oma, ranula, retention cyst. harm3rtoma. lingual thyroid, and ter;1toma.‘.” Enteric duplication c>st\ are rare at this site and more frequcntl! occur in rclation stomach. nicate However, separate

to the

small

intestine,

The

lumen

ol’ the duplication

esophagus. may

colon,

or

cystic

f’rcquently

it does no1 and exists

or tubular

lesion

that

recapitulatca

ah

type

of‘ mucoxi

;I

;I

segment of the norm31 gut.’ The lesions ma> consist of only a inucosal lining or may bc invested in an cti-

present.‘.”

It is not cntircly clear how these dupllcalions in the tongue develop;’ early suggestions are that they represent choristomas that result from “misplacement of‘ emhr\onai rchi? “’ These lesions ma> he located tiither compIctc!;L irithin the muscle’ bulk of the ionguc. \\,ith 01 I\ ithoul ;I communication to the surIXC. or more sr~p<‘rliciallq beneath the mucosa, usu:IIIL. in the zintcrior portion. althouph they may bc lo~;nd a~~~~whcr~: irom the tip ol’thc tongue to the sub;rl:lndihular ,giand’~ ’ ‘I_ IIIC latter quaintly tertned ;I “miniature

co~nn~u-

with the lumen of the gastroenLeric tracl. more

wall of mucosa. submuco~~, and multila~ercd muscularis praprLa. The mucosal lining of the cnteric duplication ma! be histologically similar to that of the segment of the gut to \vhich it is topographically retated. More ol‘tcn. hetcrotopic gastric I~UCOS;I i:, present. and peptic ulceration is thus not an unconman finding cithcr in the duplication itself or in the mucosa of the adjacent gut segment to which it communicates. Not infrequently. there is more than one tire

~t~m!:ich”

grl;ind. The lining

within

epithelium

the

submandibular

has varied

from

gastric”’

lo inlcstinal.’ 1r1dboth single and multiple 11;ILc: hccn rcportcd. .;\h the term cnterocystoma

lesions ha:,

been ;ipplied in the iiterature specifically to extragastric collections

L)I gastric

mucosa.”

’ ’ this term

would

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not apply in the second patient when the only mucosa identified was intestinal in type. The tongue itself develops from the fusion of three primordia, paired lateral swellings of the first branchial arches, and the median tuberculum impar. These structures fuse to form the body of the tongue. The posterior third, the pharyngeal portion, of the tongue is initially indicated by two elevations that d.evelop caudally; one is the copula that is formed by fusion of the bases of the second branchial arches, and the second is the large hypobranchial eminence that develops caudal to the copula from mesoderm derived from the ventromedial parts of the third and fourth branchial arches. As the tongue grows the copula is gradually overgrown by the hypobranchial eminence. This fusion is followed by continued expansion of the tongue in both length and breadth.14,15 Enteric duplications of the tongue may thus form from small inclusions of epithelium that are retained within the substance of the tongue along the lines of fusion of the various primordia that contribute to the formation of the organ. Indeed the two cases reported here show a posterior location to the cysts, in the region of the terminal sulcus. In the presence of epithelial islands, it is possible that mesenchymal components may be subsequently induced to form the (organoid structure evident to a variable extent in these lesions. However, given this hypothesis, the presence of mucosal types that differ from that normally found in the mouth is difficult to reconcile. Other theories of pathogenesis of enteric duplication cysts that have been proposed include the suggestion that enteric duplications arise from incomplete coalescence of the lacunas that form between the epithelial cells of the solid core of the elongating ‘developing gut. Normally, these spaces unite to forrn a single lumen but, according to this hypothesis, small separate lumina persist, and with subsequent development of the epithelium, together with growth and differentiation of mesenchyme, form a variably duplicated segment of the tract.‘, l4 As a variant of this theme, Bremer16 proposes that duplications of the stomach may arise by fusion of the tips of the longitudinal multiple folds that are prominent in the stomach during the second and third months of gestation. This theory, however, does not explain the mesenteric location of the intestinal duplications, their possession of mucosal types that vary from the segment of gut to which they are spatially related, or the presence of such formations in the tongue that do not develop in the form of a tube. Another theory proposes that duplication cysts form by the persistence and development of buds of

intestinal epithelium in the submucosal connective tissue of the developing gut wall. It is suggested that these buds elongate and grow, develop a lumen centrally, and induce the formation of organized stromal elements in the developing mesenchyme. The degree to which they separate from the primary gut determines whether a diverticulum or a cyst is formed. Such epithelial buds located in the submucosa of the intestine have been reported in fetuses of some mammalian species including humans, and rarely these have been seen to possess a central lumen continuous with the lumen of the gut.17 However, as these buds occur anywhere around the circumference of the intestine, this theory does not explain the almost invariable mesenteric location of intestinal enteric duplications. Further, such buds are not found in the region of the colon where enteric duplications certainly occur. Such buds occurring in the vicinity of the tongue have also not been reported. The currently favored theory was first proposed by Veeneklaas18 and later elaborated by Bently and Smith.” Veenklaas observed that intestinal duplications, particularly those that occur in the thorax, were frequently associated with vertebral clefts and rib anomalies. He suggested that they arose from disturbances in the development of the notochord and surrounding structures. Thus strands or masses of adherent entodermal cells caught up *ith the infolding of the notochordal plate, during the formation of the notochord, result in misplaced cell nests that, invested in mesoderm, develop into segments of gut variably separated from the true gastrointestinal tract. This theory explains the mesenteric aspect of the duplications, their association with vertebral anomalies, and the occasional presence of enteric cysts or sinuses within the spinal canal. Although this mechanism has been widely accepted and appears to best explain the embryogenesis of a spectrum of enteric duplications found in relation to the esophagus, stomach, and intestines, it again fails to explain the development of enteric duplications in the tongue. It becomes apparent therefore that enteric duplication cysts are a heterogeneous group of lesions that share some morphologic features, but perhaps not the same pathogenesis. The cases presented, as well as demonstrating an unusual anatomic malformation of clinical significance, expand the breadth of lesions that are included in this category and raise questions concerning the applicability of some of the theories of pathogenesis in this location. We would like to acknowledge the secretarial assistance of Heather Cooke.