Keywords
dacryocyctocele - prenatal diagnosis - Inner canthus - inferomedial - complete resolution
Introduction
Dacryocystocele, also known as lacrimal duct mucocele or amniocele or amniotocele,
is a rare variant of obstruction of the nasolacrimal duct that results in a fluid-filled,
closed sac.[1] The lacrimal duct system develops in the second month of pregnancy, at around 6
weeks of gestation. It arises from the surface ectoderm that is located between the
maxillary and the lateral nasal processes. It then begins to canalize at approximately
16 weeks of intrauterine life and is generally completed by 24th week of gestation.
However, the canalization of the distal end of the drainage system at the level of
the valve of Hasner may occur at birth or even few weeks later. Once the lacrimal
punctum becomes patent, amniotic fluid gets filled in the distal end of the duct thereby
causing distension of the duct system. There must be simultaneous distal anatomical
obstruction at the level of valve of Hasner (isolated distal obstruction is called
dacryostenosis) and a proximal fictional obstruction at the level of the Rosenmuller
valve by the distended sac preventing its retrograde drainage through the puncta.
This leads to the formation of dacryocystocele. It often resolves by the spontaneous
perforation of the distal membrane during the early neonatal period, resulting in
drainage of the accumulated fluid. Laterality and gender have not been reported significantly
in prenatal studies. This benign condition can be usually treated postnatally. If
the cysts occur bilaterally, there can be an obstruction to the nasal passage due
to their possible intranasal extension. The respiratory distress developing, thereby
often needs surgical intervention. Also, it may be a part of a few syndromes, which
makes the early prenatal diagnosis very important. In this case report, we present
a case of unilateral dacryocystocele reported as early as 26 weeks, 3 days of gestation
detected by ultrasound that spontaneously resolved by 33 weeks. This is one of the
earliest reported three-/four-dimensional ultrasound diagnosis of dacryocystocele.
Case Report
Mrs. S aged 22 years came for antenatal scan at our center. She was a third gravida
with history of two first-trimester miscarriages for which she was evaluated earlier.
The reports were all normal except for an abnormality in her karyotype (9qh+ variant).
She visited us first at 15 weeks, 4 days of gestation, and underwent a scan that was
normal. She did not opt for any genetic screening. Anomaly scan done at 22 weeks showed
normal anatomy of the fetus including face and the central nervous system. There was
an echogenic intracardiac focus in the left ventricle. She came for a reassessment
scan after a month, at 26 weeks, 3 days. The ultrasound demonstrated a unilateral
cystic lesion measuring 5.5 mm × 6.7 mm × 8.5 mm in the right inner canthus suggestive
of dacryocystocele ([Fig. 1],[2],[3]). The facial profile and the intraocular anatomy looked normal with the eyes showing
synchronous movement. The nervous system and brain anatomy were normal. She was counselled
regarding the prognosis and the need for follow-up and the postnatal assessment. However,
a follow-up scan at 34 weeks of gestation showed complete resolution of the lesion.
She had premature rupture of membranes at 38 weeks gestation and delivered a live
female baby weighing 2.8 kg. The baby had a normal APGAR (Appearance, Pulse, Grimace,
Activity, Respiration) score and did not have any external deformities or swelling
in the inner canthus.
Fig. 1 Two-dimensional ultrasound demonstrating a cystic lesion in the right inner canthus
suggestive of dacryocystocele.
Fig. 2 Three-dimensional image showing dacryocystocele in the right inner canthus.
Fig. 3 Two-dimensional parasagittal image of fetal face demonstrating the dacryocystocele.
Discussion
The prenatal diagnosis of congenital dacryocystocele has been already described. However,
literature review shows only a few reports, with the earliest diagnosis made in the
27th week of gestation.[2] As mentioned before, the potential importance of the diagnosis is the possibility
of intranasal extension thereby causing obstruction to the nasal passages (especially
if there are bilateral cysts) and may cause neonatal respiratory distress for which
surgical intervention is needed.[3] Neonates being obligate nasal breathers, there is the risk of acute respiratory
distress in the early neonatal period and a pediatrician should be present for delivery.[4] The other possible differential diagnosis ([Table 1]) of periorbital masses often includes cystic teratomas, hemangiomas, encephalocele,
dermoid cysts, nasal glioma, and rhabdomyosarcoma.[2]
Table 1
Differential diagnosis of periorbital swellings
|
Pathology
|
Dacryocystocele
|
Cystic teratoma
|
Anterior cephalocele
|
Hemangioma
|
|
Location
|
Inferomedial to the orbit
|
Superolateral to the globe
|
Midline defect with calvarial defect
|
Head/neck
|
|
Solid/cystic
|
Cystic
|
Complex
|
Solid/cystic
|
Solid/septated
|
|
Vascularity
|
Absent
|
Absent
|
Absent
|
Present
|
When the mass is unilateral, it is often difficult to differentiate between dacryocystocele
and other peri orbital lesions.
Dacryocystocele is visualized as a hypoechoic mass lesion located inferomedial to
the orbit. It can be seen in parasagittal or coronal plane including the medial angle
of the orbits and the nose. On the contrary, a hemangioma is cutaneous in origin and
is usually located in the head or neck, and can be solid or septated.[5] It is often differentiated from dacryocystocele by its peculiar Doppler patterns.[6] Dermoid cyst is situated superolateral to the orbit and has a complex appearance
and hyperechogenicity on ultrasound, often with areas of calcification. Anterior cephalocele
is a mid-line defect and is accompanied by a defect in the calvarium, and usually
hydrocephalus. Lymphangioma, neurofibromatosis, and rhabdomyosarcoma are the other
masses in the orbit, but these solid lesions are very rare. Another rare diagnostic
dilemma is mucocele of the nasolacrimal duct system and is almost never diagnosed
prenatally.[7] The typical appearance of the dacryocystocele generally allows the clear ultrasonographic
diagnosis of this pathology. Particularly important features involved in differential
diagnosis include the size, location, echogenicity, time of appearance, and the characteristics
identified in Doppler flow.[8] A possible intra cranial connection is often ruled out with the help of magnetic
resonance imaging (MRI).[9]
Prenatal diagnosis of dacryocystocele is relatively less reported in literature. Rand
and Walsh reported two cases diagnosed at around 30th to 36th weeks of gestation.[10]
[11] The earliest reported diagnosis is by Sharony et al (27th gestational weeks) in
their series describing six cases of dacryocystocele, often accompanying some pathologies
or syndromes like Canavan disease, dysplastic kidney, pyelectasis, and maternal diabetes.[2] Recurrent bilateral dacryocystocele was observed by Westbrook et al, in cases of
Wegener's granulomatosis.[12]
[13] Kim et al did a large retrospective analysis describing an overall incidence of
prenatal dacryocystoceles to be 0.43%. The incidence was higher in the early third
trimester and thereafter decreased. About 76% cases of prenatal dacryocystoceles resolved
at birth, and the gestational age at delivery was a clinically significant predictor
of its postnatal persistence.[14] In general, the lacrimal sac and the nasolacrimal duct visibility in the third trimester
was reported to be around 45% with the peak gestational age of reporting being around
32 weeks. Congenital dacryocystocele usually represents those above the 95th percentile
of the size of the lacrimal sac (i.e., >5 mm). The detection around 27 to 28 weeks
actually represents the physiological sequences of the canalization (around 24 weeks
of intrauterine life) or the opening of lacrimal punctum (range: 16–25/26 weeks).[9] Even though MRI reports suggest early detection (as early as 24 weeks), it is not
a routine investigation during antenatal period. Also, considering the cost and inconvenience
and difficulty in availability, the detection of dacryocystocele by MRI is of questionable
value. The postnatal resolution was reported in approximately 70% of cases diagnosed
by antenatal ultrasound.[8] The main thing to be noted here is the good prognosis and the timely advice that
should be given to the patient. On follow-up ultrasound, our case had complete resolution
and that itself is a key message to be delivered to the patients.
Implications for Clinical Practice
Correct diagnosis of dacryocystocele is very important and the earlier diagnosis and
accurate differentiation from the other similar pathologies along with proper counseling
and follow-up would help to manage this condition. If not resolving antenatally, postnatal
follow-up is warranted and rarely some interventions might be needed. Early detection
also would help to look for other features of associated syndromes, if any. Though
few suggest there is no increase in incidence of genetic disease or syndromic association
with the fetuses with dacryocystocele, it needs counseling of the parents to optimize
perinatal outcome.
