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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 3  |  Page : 757-760

Perilimbal conjunctival schwannoma: A rare case


Department of Ophthalmology, All India Institute of Medical Sciences, AIIMS Campus, Tatibandh, Raipur, Chhattisgarh, India

Date of Submission11-Feb-2022
Date of Acceptance05-Apr-2022
Date of Web Publication16-Jul-2022

Correspondence Address:
Dr. Lubna Khan
Additional Professor, Department of Ophthalmology, All India Institute of Medical Sciences, Great Eastern Rd, AIIMS Campus, Tatibandh, Raipur, Chhattisgarh – 492 099
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_342_22

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  Abstract 


A female aged 42 years presented to us for routine eye examination and was found to have a well-circumscribed, firm, smooth, oval nodule at the limbus of the right eye. It had increased slowly to the present size in 7 years. It is unique in being the first and largest limbal schwannoma to be reported from India. The patient had no visual or cosmetic concern. Excision followed by histopathologic evaluation revealed its nature. Special staining (S100 and reticulin) revealed it to be of neurogenic origin. Schwannomas of ophthalmic interest include those arising from the orbit. Within the globe, they have been reported to arise from the uvea. Conjunctival schwannomas are extremely rare. Role of gene mutation as a causal factor has been studied when schwannoma occurs as a part of Carney complex. Association with multiple neurofibromatosis is also documented.

Keywords: Epibulbar Schwannoma, perilimbal schwannoma, solitary neurilemmoma


How to cite this article:
Khan L. Perilimbal conjunctival schwannoma: A rare case. Indian J Ophthalmol Case Rep 2022;2:757-60

How to cite this URL:
Khan L. Perilimbal conjunctival schwannoma: A rare case. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Aug 17];2:757-60. Available from: https://www.ijoreports.in/text.asp?2022/2/3/757/351181



Considering all epibulbar schwannomas collectively, nearly a dozen cases have been documented. If limbal and perilimbal location of conjunctival schwannoma is considered, a review of documented literature shows only four cases globally: one in a 68-year-old white male[1] and another a 31-year-old Korean male,[2] while one of the remaining two cases[3] and the present case, both females, have been from India.

Schwannomas are slow-growing lesions that do not invade surrounding tissues.[4] Malignant transformation is rare.[5] Literature review shows these schwannomas to arise in various age groups with no gender predilection. In the orbit, these arise from Schwann cells of the sympathetic nerves tightly adherent to the optic nerve. Nair et al.[6] reported a conjunctival mass in a 12-year-old boy. Alam et al.[7] could demonstrate the presence of Verocay bodies in their case on histopathology.


  Case Report Top


We present the case report of a 42-year-old female presenting to us for routine eye examination. Her visual acuity was 20/40 in the right eye and 20/20 in the left eye, with refractive correction improving to 20/20. A well-circumscribed nodule was seen at the limbus at 12 o′clock position in the right eye. Ophthalmic examination revealed a well-circumscribed, smooth, off white, oval nodule in the right eye, near the corneoscleral junction at 12 o′clock position [Figure 1]. Vasculature overlying it was unremarkable with absence of feeder vessel. Under the slit beam, it was 7 mm in lateral extent and 6 mm vertically, with an elevation of 5 mm from the base. It was slipping readily and was free from underlying tenons capsule.
Figure 1: Preoperative photograph of the patient showing well-circumscribed nodule at 12 o′clock position at the perilimbal location

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Systemic examination was unremarkable.

An informed written consent for excision under local anesthesia was taken. It was adhered neither to sclera nor to cornea [Figure 2]. It was beneath the conjunctiva with no adherence to tenons capsule underneath [Figure 3].
Figure 2: The nodule seen as gross with its capsule held by forceps on the left of figure

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Figure 3: The mass seen as gross separated from the conjunctiva. Note the cut end of the conjunctiva in the figure

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Microscopically, the tumor comprised spindle cells showing alternate loose and dense areas with nuclear palisading [Figure 4]. The gross and microscopic features were consistent with schwannoma.
Figure 4: (a) Schwannoma seen in 10× magnification showing blue arrow to denote Verocay bodies.(b) The same seen in 40× magnification showing spindle cells with nuclear palisading

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Immunohistochemistry done with first generation immunostain S100 tested positive [Figure 5]a. Reticulin stain showed abundance of delicate fibers within the tumor, favoring a diagnosis of schwannoma [Figure 5]b. Absence of fibroblasts distinguished it from neurofibroma.
Figure 5: (a) S100 immunostaining revealing rust colored areas of positivity denoted by blue arrow; (b) reticulin stain showing abundance of fibers in tumor

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Systemic examination revealed no café-au-lait spots or bumps beneath the skin at other parts of the body. Features like central adiposity, proximal myopathy, amenorrhea, hirsutism, impaired glucose tolerance, and diastolic hypertension were looked for and were found to be absent in the patient.


  Discussion Top


Schwannomas in the superotemporal globe, inferior fornix, perilimbal locations, and caruncle have been documented.

Multiple endocrinal neoplasia (MEN) is a syndrome in which schwannoma may coexist with endocrinal tumors that involve the adrenals,  Sertoli cells More Details, thyroid, and ovaries.

The details of reported conjunctival schwannomas are presented in [Table 1].
Table 1: Details of previously reported conjunctival schwannomas

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Surgery is the treatment of choice.[4] Recent advances in stereotactic radiosurgery and fractionated radiotherapy in the treatment of non-vestibular schwannomas have achieved high level of tumor growth control, while preserving cranial nerve function.[13] This treatment option may be considered if schwannoma arises from inaccessible locations like ciliary body, chamber angle, or uvea. Analyzing the possible sources of origin in our case needs an overview of nerves in the limbal region. These can be categorized into three groups as follows:

  1. limbal plexus of nerves supplying sensory and autonomic innervations to limbal vessels;
  2. sensory nerves supplying the conjunctiva, namely, lacrimal, frontal, and nasociliary branches of ophthalmic division of the fifth cranial nerve; and
  3. those entering the cornea: subepithelial plexus beneath the Bowman's membrane and stromal nerves.


In a study done by Lawrenson et al.,[14] it was shown that density of these corpuscular nerve endings varies in different parts of conjunctiva, being maximally concentrated in the area of bulbar conjunctiva covered by upper lid, their incidence decreasing in interpalpebral zone, being fewest in the area covered by lower lid.[14] Oppenheimer et al.,[15] in 1958, found that a majority of conjunctival nerves terminated as free nerve endings often in relation to blood vessels.

All nerves branch extensively and terminate as knob-like endings, similar to Krause bodies.[16] Lawrenson JG et al. demonstrated maximal number of these nerves in 1 mm circumference, 0.5 mm from corneoscleral junction using special staining method.[14] If perilimbal location is considered, of the four cases reported in global literature, three were arising from conjunctiva covered by upper lid (one at 2 o′clock, one at 11 o′clock, and in our case at 12 o′clock), while it was in the interpalpebral area in a 68-year-old male.

Researchers such as Lawrenson et al.[14] have analyzed the anatomical features of nerve endings in terms of distribution and density characteristics. Corneal sensory nerves branch extensively and terminate as knob-like endings, similar to Krause bodies.[16] In all the previously published schwannomas, the authors could not explain why schwannoma occurs at the perilimbal location. It was the work of Lawrenson JG et al.[14] which showed the density characteristic of end bulb of Krause, being concentrated maximally at the perilimbal location, and hence the occurrence of conjunctival schwannoma here. Among the very few limbal schwannomas arising from the conjunctiva, Agarwal et al.[3] have reported one case from India.

The only case of schwannoma of bulbar conjunctiva from Japan has been reported by Oshima et al.[17]

In 1987, Grossniklaus et al.[10] could demonstrate presence of Antoni A and Antoni B cells in the excised conjunctival mass.

The fact that Schwannomas occur in perilimbal location has been reported in literature. Also, the fact that density of end bulb of Krause is maximal in perilimbal location is also known, but no attempt was made by previous authors to explain why it is the commonest location. This is the first time that the author has given anatomical reason for occurrence at this location in this case report, giving an explanation that the incidence of occurrence correlates with the distribution of sensory nerve endings. The incidence of schwannoma is highest where the density of nerves is maximal.


  Conclusion Top


Perilimbal conjunctival schwannoma may be considered as one of the differentials in case patient presents with limbal or perilimbal nodule. If histopathology proves it to be a neurilemmoma, clinical features of Multiple Endocrinal Neoplasia (MEN) and Carney Complex should be looked for.

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.



 
  References Top

1.
Charles NC, Fox DM, Avendano JA, Marroquin LS, Appleman W. Conjunctival neurilemoma: Report of 3 cases. Arch Ophthalmol 1997;115:547–9.  Back to cited text no. 1
    
2.
Kim SUK, Gu MJ, Lee JK, Park DJ. A case of Bulbar conjunctival schwannoma. J Korean Ophthalmol Soc 2009;50:1111-4.  Back to cited text no. 2
    
3.
Agarwal R, Pal S, Chaudhary N, Sharma K, Kanaujia V. Limbal schwannoma: Clinicopathological study of a case with review of literature. OJO 2019;12:197-9.  Back to cited text no. 3
    
4.
Tezer MS, Ozcan M, Han O, Unal A, Ozlugedik S. Schwannoma originating from the infraorbital nerve: A case report. Auris Nasus Larynx 2006;33:343-5.  Back to cited text no. 4
    
5.
Subramanian N, Rambhatia S, Mahesh L, Menon SV, Krishnakumar S, Biswas J, et al. Cystic schwannomas of the orbit a case series. Orbit 2005;24:125-9.  Back to cited text no. 5
    
6.
Nair AG, Kaliki S, Mishra DK, Dave TV, Naik MN. Epibulbar schwannoma in a 12 year old boy: A case report and review of literature. Indian J Ophthalmol 2015;63:620-2.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Alam MS, Poonam NS, Biswas J, Krishnakumar S. Epibulbar schwannoma: A case report and review of the literature. Can J Ophthalmol 2016;51:e155-7.  Back to cited text no. 7
    
8.
Dabezies OH, Penner R. Neurofibroma or neurilemmoma of the bulbar conjunctiva. Arch Ophthalmol 1961;66:73-5.  Back to cited text no. 8
    
9.
Vincent NJ, Cleasby GW. Schwannoma of the bulbar conjunctiva. Arch Ophthalmol 1968;80:641-2.  Back to cited text no. 9
    
10.
Grossniklaus HE, Green WR, Luckenbach M, Chan CC. Conjunctival lesions in adults. A clinical and histopathologic review. Cornea 1987;6:78–116.  Back to cited text no. 10
    
11.
Le Marc'hadour F, Romanet JP, Fdili A, Peoc'h M, Pinel N. Schwannoma of the bulbar conjunctiva. Arch Ophthalmol 1996;114:1258-60.  Back to cited text no. 11
    
12.
Andreoli CM, Hatton M, Semple JP, Soukiasian SH, Fay AM. Perilimbal conjunctival schwannoma. Arch Ophthalmol 2004;122:388-9.  Back to cited text no. 12
    
13.
Pollock BE, Foote RL, Stafford SL. Stereotactic radiosurgery: The preferred management for patients with nonvestibular schwannomas? Int J Radiat Oncol Biol Phys 2002;52:1002-7.  Back to cited text no. 13
    
14.
Lawrenson JG, Ruskell GL. The structure of corpuscular nerve endings in limbal conjunctiva of the human eye. J Anat 1991;177:75-84.  Back to cited text no. 14
    
15.
Oppenheimer DR, Palmer E, Weddell G. Nerve endings in the conjunctiva. J Anat 1958;92:321-52.  Back to cited text no. 15
    
16.
Belmonte C, Tervo TT, Gallar J. Sensory innervation of the eye. In: Levin LA, Nilson SFE, Ver Hoeve J, Wu S, Kaufman PL, Alm A, editors. Adler's Physiology of the Eye. 11th ed. China: Elsevier Saunders; 2011. p. 363-84.  Back to cited text no. 16
    
17.
Oshima K, Kitada M, Yamadori I. Neurilemoma of the bulbar conjunctiva. Jpn J Ophthalmol 2007;51:68-9.  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

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