|Year : 2022 | Volume
| Issue : 2 | Page : 531-533
Possible abnormal origin of inferior oblique from a congenital dermoid cyst: A case report
Uzma Sardar, Fariha Taimur, Amna Manzoor, Maheen Akbar, Saadullah Ahmad, Tayyab Afghani
Department of Orbit, Oculoplastics and Ocular Oncology, Al- Shifa Trust Eye Hospital, Rawalpindi, Pakistan
|Date of Submission||18-Jul-2021|
|Date of Acceptance||30-Sep-2021|
|Date of Web Publication||13-Apr-2022|
53-A, Lane 7A, Gulistan Colony, Rawalpindi
Source of Support: None, Conflict of Interest: None
A 4-year-old female child presented with a cystic swelling medially along the floor of the orbit with mild ipsilateral medial canthus dystopia on the left side. This swelling was present since birth with no significant orbital dystopia or any extraocular movement defects. During surgery, a trilobed yellowish cyst was found near the inferomedial wall of the orbit. Incidentally, the inferior oblique muscle was found to be originating from the medial lobe of the cyst. The cyst was removed completely, and the inferior oblique was reinserted to the inferomedial orbital margin. Histopathology was consistent with dermoid cyst. To the best of the authors' knowledge, the case of abnormal origin of inferior oblique muscle from an orbital dermoid cyst has not been reported before.
Keywords: Abnormal origin, dermoid, extraocular muscle, inferior oblique
|How to cite this article:|
Sardar U, Taimur F, Manzoor A, Akbar M, Ahmad S, Afghani T. Possible abnormal origin of inferior oblique from a congenital dermoid cyst: A case report. Indian J Ophthalmol Case Rep 2022;2:531-3
|How to cite this URL:|
Sardar U, Taimur F, Manzoor A, Akbar M, Ahmad S, Afghani T. Possible abnormal origin of inferior oblique from a congenital dermoid cyst: A case report. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 May 18];2:531-3. Available from: https://www.ijoreports.in/text.asp?2022/2/2/531/342911
One of the most common types of cystic orbital lesion in children is dermoid/epidermoid cyst., These develop because of entrapment of surface ectoderm along the suture lines. They are noticed in the first year of life along the orbital rim as a painless swelling; however, deeper cysts may get noticed during young adulthood as they enlarge and cause proptosis.,,,, It is exceedingly rare that a congenital orbital cyst interferes with the developmental origin of the extraocular muscles. Herein, we report a case of a 4-year-old child with a multilobed orbital dermoid cyst giving aberrant origin to inferior oblique muscle.
| Case Report|| |
A 4-year-old female child [Figure 1] presented with left visible yellowish palpable cystic swelling along the medial part of the floor of the orbit that was present since birth. The extraocular movements were normal. There was ipsilateral mild medial canthus dystopia. The CT scan showed a well-defined multilobed lesion in the floor of orbit that showed contrast enhancement [Figure 2].
|Figure 2: CT scan images, red arrows indicating multilobed lesion in the floor of the orbit: (a) coronal view; (b) sagittal view|
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Anterior inferior orbitotomy was performed and a well-defined, yellowish cystic but firm trilobed swelling was identified. The middle lobe was more posterior than the medial and lateral lobes [Figure 3]a. The inferior oblique was found to be arising from the lateral anterior edge of the medial lobe of the cystic mass [Figure 3]b.
|Figure 3: (a) Trilobed dermoid cyst; (b) inferior oblique arising from medial lobe|
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The inferior oblique was identified, isolated, and secured. The medial canthal ligament was also pushed and stretched upwards. All three lobes were dissected free, together, and jointly. The medial lobe was found to be pushing into the inferomedial orbital wall, creating a small crater. This lobe leaked during surgery, and oozing white cheesy material was seen. The surgical site was thoroughly washed. No postoperative reaction to dermoid contents was observed during immediate or late follow-up. The attached inferior oblique was excised and reattached at its new location in the inferomedial orbital margin, while the trilobed lesion was removed. The histopathology revealed that the wall of the cyst was composed of skin and there was diffuse infiltration of plasma cells, lymphocytes, and histiocytes, and the lumen was filled with lamellated keratin, thus confirming the lesion to be a dermoid cyst. Postoperatively, there was no dystopia. There was lower eyelid retraction as compared to the other normal lower eyelid [Figure 1]b.
| Discussion|| |
The inferior oblique (IO) is a slender extraocular muscle responsible for elevation, abduction, and extorsion of the eye. Studies of the developmental origin of extraocular muscles suggest that the IO arises from the inferior mesenchymal complex along with the inferior rectus (IR) muscle. The process of development of IO muscle originates from the pre-mandibular mesodermal condensation at the ventrocaudal end when the embryo is at 8.5 mm stage of development. The mesodermal condensation then develops into three muscles, namely IR, MR and IO. In the 12.5-mm stage, the inferior rectus and inferior oblique are separated and grow toward their points of origin and insertion. The caudodorsal end is inserted medial to lateral rectus insertion and caudoventral to the orbital surface of maxilla. Dermoid cysts in the orbital area usually arise between the third and the fifth week of gestation along the zygomaticofrontal suture. The caudoventral end of the inferior oblique muscle that insert into the orbital surface of the maxilla migrates at the seventh week of gestation (12.5 mm stage). According to the author, in this case, it is probably the developing dermoid that has forced IO to insert onto the side of the surface of the dermoid instead of inserting at its normal position.
Dermoid cysts in the orbital and periorbital region are generally sutural dermoids. In this case, the dermoid cyst could be arising from the anteromedial aspect of the maxillary-lacrimal sutures. As these cysts are subperiosteal in nature or have a periosteal attachment, there is a chance of the IO insertion region being involved by the dermoid cyst, thus making it appear as if the IO has originated from the dermoid cyst itself, and hence the possibility of inferior oblique arising from the original origin, which could have been later modified by the dermoid cyst evolution. However, preoperative direct observation showed that the inferior oblique was arising from the surface of the dermoid away from its normal bony origin. Thus, there is an equal possibility that an already embryological evolved dermoid cyst blocked the further passage of the developing inferior oblique toward its actual origin and thus inferior oblique got attached to the surface of the dermoid instead of the bony origin.
Recent evidence shows that the majority of the periorbital cysts appear before 1 year of age and those appearing after the first year are usually associated with orbital dystopia.,, The dermoid cyst arising in inferonasal orbit may interfere with normal IO migration during gestation and IO may be seen as dividing the developing cyst, giving it a bilobed morphology, or it can push the developing inferior oblique origin posteriorly, which is reported before, in which the inferior oblique (IO) muscle was originating posteriorly from its normal site of origin, 10–12 mm behind the medial orbital margin. The case reported here is unique as the inferonasal dermoid itself is giving origin to inferior oblique muscle rather than changing its site of origin or altering its morphology. What led to the inferior oblique attaching itself to the dermoid cyst rather than diverting its path to a new location on the orbital margin as reported earlier is only a matter of speculation. Probably the size of the dermoid, timing of its origin, etc., might have played some role in deciding the final destination of inferior oblique origin in current and previously reported cases.
Howard et al. reported two cases in which orbital dermoids were present in the lateral rectus muscle. Similarly, another case was seen in which a dermoid cyst was lying within the lateral rectus muscle and the patient presented with incomitant esotropia of the involved eye. Four cases were reported in 1999 in which congenital orbital cysts were seen to be arising from the common sheath of levator palpebrae superioris muscle and superior rectus muscle in the upper fornix. In all these cases, the dermoid cyst was seen to be arising within the muscle or from muscle sheath with normal origin and insertion of muscles. The case that we are reporting here is one of its kind as inferior oblique muscle was seen to be arising from one of the lobes of a trilobed dermoid cyst instead of its normal origin from the orbital floor, that is, the medial orbital surface of the maxilla. The attached IO was excised from the cyst and reattached at its new location in the inferomedial orbital margin. Postoperatively, no diplopia was seen and extraocular movements were fine. This finding is clinically important for ophthalmologists, oculoplastic surgeons, neurosurgeons, and maxillofacial surgeons as during surgical removal of these cysts, one should be cautious about abnormal origin or attachment of the muscle on the cyst in order to prevent iatrogenic trauma or loss of muscle. If such abnormal attachment of muscle is found, it should be detached from the aberrant site and secure attachment to its appropriate site should be considered to regain normal anatomy.
| Conclusion|| |
The unique finding reported in the case is alarming. The dermoid cyst excision is one of the most routinely performed surgery. The surgeons should be equally vigilant and cautious even while performing such routine procedures as such atypical findings can result in iatrogenic trauma to important ocular or orbital structures. By Identifying the aberrant or atypical findings we can rectify the abnormality and normal anatomy and functionality can be restored.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]