Rare case of inferotemporal orbital fat prolapse – Clinical, histopathologic, and anterior segment optical coherence tomography correlation

Rama Rajagopal; Gaurav Chauhan; Janarthanam J Balaji

doi:10.4103/IJO.IJO_2736_22

CASE REPORT

Year : 2023 | Volume : 3 | Issue : 2 | Page : 519-520

Rare case of inferotemporal orbital fat prolapse – Clinical, histopathologic, and anterior segment optical coherence tomography correlation

Rama Rajagopal¹, Gaurav Chauhan¹, Janarthanam J Balaji²
¹ Department of Cornea and Refractive Surgery, Sankara Nethralaya, Medical Research Foundation, Chennai, Tamil Nadu, India
² Department of Optometry, Sankara Nethralaya, Medical Research Foundation, Chennai, Tamil Nadu, India

Date of Submission	18-Oct-2022
Date of Acceptance	14-Dec-2022
Date of Web Publication	28-Apr-2023

Correspondence Address:
Rama Rajagopal
Department of Cornea and Refractive Surgery, Sankara Nethralaya, Medical Research Foundation, 41, College Road, Chennai - 600 006, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJO.IJO_2736_22

Abstract

Orbital fat prolapse (OFP) is the herniation of intraconal fat into the subconjunctival space, which occurs mostly in the superotemporal quadrant and is more common bilaterally. We report a rare case of unilateral inferotemporal OFP and its anterior segment optical coherence tomography (ASOCT) features. On ASOCT, the lesion appeared uniformly smooth with no definite capsule. Fat lobules appeared hyporeflective, while the interlobular septae appeared hyperreflective. A hyporeflective space was noted, separating the fat and the overlying conjunctival stroma. This space was, however, obliterated in the areas corresponding to the maximum convexity of the lobules. These ASOCT findings correlate with the described histopathologic features of the OFP described in literature. Inferotemporal OFP and corresponding ASOCT features, to the best of our knowledge, have not been reported previously. We also propose its role in documenting progression that can aid in surgical decision-making.

Keywords: Anterior segment optical coherence tomography, inferotemporal quadrant, orbital fat prolapse

How to cite this article:
Rajagopal R, Chauhan G, Balaji JJ. Rare case of inferotemporal orbital fat prolapse – Clinical, histopathologic, and anterior segment optical coherence tomography correlation. Indian J Ophthalmol Case Rep 2023;3:519-20

How to cite this URL:
Rajagopal R, Chauhan G, Balaji JJ. Rare case of inferotemporal orbital fat prolapse – Clinical, histopathologic, and anterior segment optical coherence tomography correlation. Indian J Ophthalmol Case Rep [serial online] 2023 [cited 2023 Jun 10];3:519-20. Available from: https://www.ijoreports.in/text.asp?2023/3/2/519/374982

Orbital fat prolapse (OFP) is an uncommon condition that occurs most commonly bilaterally in elderly males, wherein the intraconal fat herniates to the subconjunctival space.^[1] The most common location of the OFP is the superotemporal region, and it has rarely been reported in the inferior or inferonasal region.^[2],[3] The exact etiology of the condition is unknown, but it possibly occurs due to the weakening of the Tenon's capsule or intermuscular septa, resulting in the herniation of fat.^[1],[4] Most of the patients are asymptomatic, and OFP is an incidental finding. Characteristic findings using magnetic resonance imaging (MRI), computed tomography scan (CT scan), and ultrasound biomicroscopy (UBM) have been described.^[5],[6] Surgery is considered only when the patient is symptomatic in terms of foreign body sensation, cosmesis, and in cases of doubtful diagnosis. Clinical mimics of OFP in the younger age are dermolipoma, dermoid cyst, and lymphoma and in the elderly population are lymphosarcoma and adipocytic neoplasms like pleomorphic lipoma.^[1],[2],[7] In our report, we highlight the features of OFP in anterior segment optical coherence tomography (ASOCT) in terms of diagnosis and propose its role in understanding progression.

Case Report

A 52-year-old male presented with a slowly growing yellow-colored subconjunctival lesion for the last 3 years. There was no history of f trauma or surgery, and systemic history was negative for thyroid disorders, obesity, or sleep apnea. On examination, a yellow-colored subconjunctival lesion, which was mobile with a smooth surface, was noted in the inferotemporal region of the left eye [Figure 1]a. The posterior border of the lesion was not evident on clinical examination [Figure 1]b, and the lesion had fine superficial blood vessels [Figure 1]c. Clinical findings were suggestive of OFP. There was no evidence of floppy eyelids or eyelid laxity. The rest of the ophthalmic examination of both eyes was normal.

Figure 1: Clinical photograph of the left eye showing inferotemporal fat prolapse. (a) Inferotemporal orbital fat prolapse in the primary gaze (arrow). (b) Subconjunctival, yellow-colored lesion seen more prominently in the right gaze: the posterior extent of the lesion is not fully evident (arrow). (c) Magnified view of the lesion showing fine superficial blood vessels (arrows)

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ASOCT of the lesion showed no definitive capsule. The fatty tissue arranged in lobules appeared homogeneously hyporeflective. The fat lobules were separated by a hyperreflective membrane corresponding to interlobular fibrous septae, described as a histopathologic feature of the lesion in literature [Figure 2]a. A hyporeflective space was noted separating the fat and the overlying conjunctival stroma. However, this space was obliterated in areas corresponding to the maximum convexity of the fat-laden lobules. Overlying conjunctival epithelium and stroma appeared of normal reflectivity. The underlying sclera was not visible possibly due to backshadowing [Figure 2]b.

Figure 2: Anterior segment optical coherence tomography features of the OFP. (a) Hyporeflective homogenous fatty tissue arranged in lobules separated by hyperreflective interlobular fibrous septae (outlined by arrows). (b). Hyporeflective space between the fat and the overlying conjunctival stroma (arrow). The space is obliterated in areas of maximum convexity (arrowheads). No capsule is noted. Overlying conjunctival epithelium and stroma are normal. The underlying sclera is not visible (asterisk). OFP = orbital fat prolapse

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The patient was advised periodic review as he was asymptomatic, and the lesion was cosmetically acceptable.

Discussion

OFP is reported bilaterally in the superotemporal region in the elderly obese male population.^[4] It is believed to be associated with the weakening of the Tenon's capsule and intermuscular septum due to aging, surgery, or trauma^[1],[4] and has also been described in thyroid orbitopathy due to an increase in intraorbital pressure,^[8] floppy eyelid syndrome,^[1] lower lid entropion,^[1] and in Goldenhar syndrome.^[6] There is only one case each of inferior and inferonasal prolapse reported.^[2],[3] It has been postulated that involutional changes weaken the orbital septum, suspensory ligaments, and the Tenon's capsule, resulting in the fat herniating superiorly as the eye bags down and making inferior prolapse less likely.^[2]

OFP is an incidental finding in most cases as it is covered by the upper lid. Patients with inferior prolapse may present earlier. Most of the cases are observed, but occasionally surgical excision is considered if patients are symptomatic, cosmetically concerned, or in case of a doubtful diagnosis.

The histopathology of the OFP has been described in different studies. On macroscopic examination, the lesion appears yellow in color with a smooth surface and has no capsule. Microscopically, distinct lobules of uniform-sized, mature adipocytes separated by delicate fibrovascular septae have been described. Other characteristic features include Lochkern cells and floret-like giant cells within and adjacent to fibrous septae.^[4],[7] The internal details delineated histopathologically, including the absence of a capsule and the presence of distinct lobules laden with adipocytes separated by delicate fibrovascular septae, could be well appreciated on ASOCT.

The role of ASOCT has been well established in corneal disorders and conjunctival diseases including surface conjunctival tumors like ocular surface squamous neoplasia, pigmented lesions besides lymphoma, and ocular surface disease. On ASOCT, lymphoma also appears as a hyporeflective and homogenous subepithelial mass with normal reflectivity and thickness of the overlying epithelium.^[9],[10] However, the presence of fibrous septae separating the fat lobules and the other features noted in OFP in our study help to differentiate it from lymphoma.

CT scan and MR images of OFP show that herniated fat is homogenous and has continuity with the intraconal fat. The attenuation on CT scans and signal intensity on MR images were identical for both OFP and intraconal fat.^[6] Besides this, CT scan and MRI have been described to differentiate OFP from dermolipoma.^[6] OFP on UBM is described as having a smooth surface without a distinct capsule and medium reflectivity.^[5] The findings on the CT scan, MRI, and UBM corroborate with the ASOCT images, as they show homogeneous reflectivity of the fat with no capsule. However, resolution of the ASOCT images is better than that of other imaging modalities. These modalities fail to demonstrate some of the microscopic structural details of the lesion, which is possible with ASOCT.

Conclusion

Our ASOCT findings in OFP corroborated and complimented the clinical and histopathologic findings. It clearly delineated the internal structure of OFP better in comparison to other diagnostic modalities. It can also be used to differentiate OFP from other mimicking lesions like lymphoma. In the future, we intend to perform serial ASOCT to understand the feasibility of quantifying progression of prolapse, which may further aid in surgical decision-making.

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

Nil.

Conflicts of interest

There are no conflicts of interest.

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