Histopathological Diagnostic Dilemma in Retrorectal Developmental Cysts: Report of a Case and Review of the Literature
Meltem AZATÇAM1, Eren ALTUN1, Veli AVCİ2
1Department of Medical Pathology, Bingöl Maternity and Children's Hospital, Bİngöl, TURKEY
2Department of Pediatric Surgery Clinics, Bingöl Maternity and Children's Hospital, Bİngöl, TURKEY
Keywords: Cyst, Developmental, Duplication, Rectal
Retrorectal developmental cysts are lesions that are classified according to their histopathological characteristics and origins. The major types
are epidermoid cyst, dermoid cyst, rectal duplication cyst, rectal cystic hamartoma and teratoma. These cysts grow slowly and the majority of
cases are asymptomatic. Total excision is required and histopathological examination should be carefully performed for retrorectal localized
developmental cysts, since the cystic lesions may show malignant transformation. Here, a 3-year-old male patient with retrorectal mass, which
was histopathologically compatible with tailgut cyst, is presented and the differential diagnosis of retrorectal developmental cysts is discussed.
Retrorectal developmental cysts are smooth-bordered,
thin walled and unilocular/multilocular cystic lesions
that are classified according to their histopathological
characteristics and origins. They are though to originate
from caudal embryonic remnants. Developmental cysts,
most of them being congenital, are lesions frequently
localized in the retrorectal region1,2
. The major types of
retrorectal cysts are epidermoid cyst, dermoid cyst, rectal
duplication cyst, rectal cystic hamartoma and teratoma3-5
. Tailgut cyst, also known as retrorectal cystic hamartoma,
is a congenital lesion of embryologic tailgut origin, located
in the retrorectal space2,4,6
. Rectal duplication cysts
are rare lesions that constitute 5% of all developmental
. Developmental cysts are seen more frequently
in females than males (3:1) during childhood and young
. Most cases are asymptomatic. They can
rarely be diagnosed in newborns and infants when they
cause a macroscopic lesion detectable during physical
examination such as rectal prolapsus7,9
. These cysts,
usually having a multilocular structure, may be lined by
respiratory, squamous, transitional, columnar, ciliated
columnar, mucinous and gastrointestinal epithelium.
Some of them contain organized/disorganized smooth
muscle bundles, located under the epithelium. Except for
epidermoid/dermoid cysts, the lumen is filled with mucin
or gelatinous material. Granulomatous inflammation and
foreign body-type giant cell reaction may be observed in tailgut cysts4,6,10
. Complications such as infection, fistula
formation or malignancy development have been reported
in developmental cysts2,7,11
. We aimed to present our
3-year-old male patient who had a retrorectal located cyst
that caused intestinal prolapsus through the anus.
A 3-year-old male patient presented to the pediatric surgery
outpatient clinic with the complaint of prolapsed intestine
through anus. In his physical examination, a fluctuating
cystic mass was palpated under the intestinal mucosa of
the prolapsed intestinal segment. Following aspiration of
the cyst by a needle and draining viscous, transparent fluid
with a mucoid nature, the mass was surgically excised.
The specimen received by our pathology laboratory was
2.3 x 1.0 x 0.7 cm in size. Macroscopically, one side of the
specimen had mucosal characteristics with white/pink
color and a smooth appearance while the other side had an
irregular appearance. The entire specimen was processed
following staining of the irregular surface with Indian ink.
On light microscopic evaluation, the full-thickness colon
wall had an organized structure at one side, and continued
with loose fibrous connective tissue and the cystic lesion
adjacent to the colon wall (Figure 1A,B). The microscopic
examination of the cyst wall showed granulation tissue and
patchy columnar and respiratory epithelium, with scattered
inflammatory cells under the epithelial surface in most of the
areas, together with a muscular layer continuing throughout the entire lesion. In focal areas, several small, tubular, and
gland-like structures were noted (Figure 1A,B,2). Except for
the actual intestinal wall, no neural plexus was observed in
areas matching the cyst wall. Immunohistochemical studies
revealed cytoplasmic immunoreactivity with cytokeratin 7
in the cyst epithelium, while there was no reaction with
cytokeratin 20. Thyroid transcription factor-1 showed sparse nuclear immunoreactivity. Focal immunoreactivity
was observed with synaptophysin and neuron-specific
enolase on the cyst wall, which could not be interpreted
to be in favor of a plexus. No reaction was detected with
chromogranin. Based on the histopathological and
immunohistochemical results, the case was interpreted as
a tailgut cyst.
Click Here to Zoom
|Figure 1: A) Cyst wall and muscularis propria of the intestine.
B) Organized, full-thickness intestinal wall (H&E; x40).
Click Here to Zoom
|Figure 2: The cyst wall, with the surface lined by respiratory
epithelium and underlying muscle layer (H&E; x100).
Developmental cysts of the rectal region are smooth-bordered,
thin-walled, unilocular/multilocular cystic lesions,
which are classified according to their histopathological
characteristics and origins. Since these cysts are slowly
growing masses, most cases are asymptomatic and are diagnosed
incidentally. Constipation, bleeding, perineal pain,
and feeling of fullness become manifest with increasing
cyst size. Infected cysts may cause perianal abscess and fistulas.
Malignancy development has been rarely reported2,4,7,10
Epidermoid cyst, dermoid cyst, duplication cyst, cystic
hamartoma (tailgut) and teratoma are considered in the
differential diagnosis of cystic lesions of the rectal region4,5. Imaging techniques such as ultrasonography, computerized
tomography and magnetic resonance imaging are
performed for the differential diagnosis of retrorectal cystic
lesions. However, the differential diagnosis is quite difficult
by radiological methods12 and the definitive diagnosis is
made by histopathological examination, in association with
the clinical and radiological findings12,13.
Epidermoid cyst is unilocular, lined by squamous
epithelium that contains no skin adnexa, and has no smooth
muscle in its wall. In dermoid cyst, unlike epidermoid cyst, skin adnexa are observed under the squamous epithelium.
Duplication cyst is unilocular, and lined by respiratory and
gastrointestinal epithelium; its wall contains two organized
muscle layers (muscularis mucosa and muscularis propria)
together with neural plexus. Rectal cystic hamartomas
(tailgut) are generally multilocular, and may be lined by
squamous, transitional, columnar, ciliated columnar and
mucinous epithelium; they contain disorganized smooth
muscle bundles under the epithelium. Teratomas are lesions
containing tissues of all three germ layers, and are usually
unilocular4-6,10. In our case, columnar and respiratory
epitheliums were present at the surface and an organized
and thin structure consistent with muscularis mucosa was
noted under the epithelium while absence of an organized
muscularis propria of the cyst was noteworthy.
Among developmental cysts, the duplication cyst is one
that is most frequently associated with complex genital
and urinary system anomalies3. A 12-year-old patient,
having findings of disease and malformation accompanying
tailgut cyst has also been reported in the literature14. No
associated anomaly was detected in our patient.
In classical textbooks, retrorectal cystic hamartoma is
reported to be more frequent in children, young adults, and
females2,10. According to the literature, the age range
of retrorectal hamartoma is 0-80 years7. Although it is
congenital, the average age for diagnosis of this lesion has
been reported as 36 years10; however, tailgut cysts have
been reported in a newborn patient in the literature7.
Since our case was a 3-year-old male patient, he belonged
to the group that manifests symptoms in the early period,
when the literature is taken into consideration.
Developmental cysts that were fistulized and had solid
components, or which developed malignancies such as
adenocarcinoma and neuroendocrine carcinoma have also
been reported2,7,11,15. Our case was entirely cystic in
nature, having no solid component. No finding in favor of
malignancy was detected.
Tailgut cysts are cystic lesions that develop from the tailgut
and embryological remnants of neuroenteric canal, and
are located in the presacral-retrorectal space; they contain
mucoid, gelatinous fluid, and are usually multilocular2,10. Duplication cysts, however, have unilocular
structure3. Our literature review revealed that tailgut
cysts have been found to be retrorectal, with most cases
having a multilocular structure. However, in one of the
reported cases, the cyst was unilocular in structure and
adenocarcinoma was diagnosed11. In our case, the cystic
lesion was again in a retrorectal location and showed a
Histopathologically, tailgut cysts are lined by squamous,
transitional, columnar, and ciliated columnar epithelium;
scattered subepithelial muscle bundles are also observed.
Duplication cyst is lined by epithelium of respiratory
and gastrointestinal systems and it contains two layers of
organized muscle layers5,6,10. In reports related to
this topic, the cyst epithelium has similar features to those
written in classical textbooks in most of the cases. However,
there are reports describing ileal duplication cysts lined
by gastrointestinal, respiratory, or patchy-form squamous
epithelia in the literature12. While the cyst surface was
eroded in most of the areas in our case, it was lined by
columnar and respiratory epithelium in focal areas and a
single and organized muscle layer was observed under the
surface epithelium in most of the areas. This has led us to
the differential diagnosis of the cyst with a duplication cyst.
However, when the diagnostic criteria of duplication cyst
are taken into consideration, organized and two-layered
muscle has to be taken into account. In our case, an intestinal
wall with organized structure and loose connective tissue
adjacent to the wall were observed; this continued with the
organized muscle layer of the cyst. The epithelium of the
cyst was eroded and showed inflammatory cells and small,
congested vascular structures in most of the areas; in focal
areas, the cyst surface contained columnar and respiratory
epithelium. Absence of two-layered muscle decreased the
possibility of duplication cyst as a diagnosis. However, as
some reports have suggested, the probability of having a
single and common muscularis propria created confusion
in favor of a duplication cyst16,17. For this reason,
the comment of “duplication cyst could not be excluded
definitely” was added to our report.
In some cases, the histopathological information published
in classical textbooks has been not sufficiently descriptive
for the differential diagnosis of duplication cyst from rectal
cystic hamartoma. In patients who are not supported
by detailed clinical and radiological data, a difficulty in
diagnosis is encountered. Retrorectal developmental cysts
are lesions that may have malignant transformation and
total excision with careful histopathological evaluation of
the cyst is therefore mandatory.
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