Schwannoma of the eyelid: Apropos of two cases

Schwannoma, also referred to as neurilemmoma, is a benign tumor of peripheral nerve arising from Schwann cells that form the neural sheath. Schwannoma of ophthalmic interest is rare although it has been reported in relation with the orbit, and less frequently with the uveal tract and conjunctiva. Isolated eyelid schwannoma is extremely uncommon. Up until now, only eight cases have been reported in literature. Herein, we report two cases of eyelid schwannoma. may A 29-year-old woman who underwent laser in situ keratomileusis (LASIK) for myopic astigmatism in both eyes presented with severe pain, photophobia and decreased visual acuity in the le ft eye eight days a ft er surgery. Examination revealed severe anterior uveitis with (cid:222) brinous exudates in the anterior chamber, (cid:223) ap edema and epithelial bullae. Laboratory investigations for uveitis were negative and the patient required systemic and intensive topical steroids with cycloplegics to control the in (cid:223) ammation. This case demonstrates that severe anterior uveitis may develop a ft er LASIK and needs prompt and vigorous management for resolution. (cid:223)


Case Reports
Case 1 A 47-year-old man was referred to us with a one-year history of a slowly enlarging, painless nodule on his right lower eyelid. Ocular examination was normal except for the presence of a Þ rm, non-tender nodule measuring 7 × 7 × 6 mm in the medial third of the right lower eyelid. There were no clinical Þ ndings indicative of neuroÞ bromatosis. The patient was operated under local anesthesia; tumor was completely removed via a horizontal eyelid crease incision. The postoperative course was uneventful and the patient was asymptomatic Þ ve years later.
Pathological studies showed an encapsulated spheric mass (6 mm in diameter) on macroscopic examination. Microscopic examination revealed a biphasic patt ern, with highly cellular areas of non-pigmented spindle cells, containing elongated nuclei arranged in fascicles, which were separated by homogenous acellular material (Antoni A patt ern). In other areas, the cells were more oval, and had rounded nuclei, clear cytoplasm and less basement membrane, and were loosely entwined within a clear myxoid matrix (Antoni B patt ern) [ Fig. 1]. No histopathologic features of malignancy were present. Immunochemistry for S-100 protein was strongly positive, but tumor cells did not react with HMB45. The Þ nal diagnosis was benign schwannoma Type A and B of the eyelid.

Case 2
A 20-year-old woman was referred to us for a chalazion of her left lower eyelid, which had been operated three times in four years. No tissues had been submitt ed for histopathological examination in earlier surgical procedures. Ocular examination was normal except for the presence of a Þ rm, non-tender painless nodule measuring 13 × 8 × 8 mm located in the middle of the left lower eyelid, independent of the lid margin [ Fig. 2]. There were no clinical Þ ndings indicative of neuroÞ bromatosis. The lesion was removed under local anesthesia by a full-thickness resection of the lid around the tumor.
On macroscopic examination the nodule was well-circumscribed, non-encapsulated, measuring 10 mm in diameter with yellow appearance on cut sections. Microscopic examination revealed fascicules and bundles of non-pigmented spindle cells with elongated bland nuclei, and abundant extracellular collagen with adipocytes and squamous cells displaying an Antoni A patt ern. There was no mitotic activity. Immunochemistry for S-100 protein was strongly positive, but tumor cells did not react with HMB45 [ Fig. 4]. Final diagnosis was benign schwannoma of the eyelid.

Discussion
Schwannoma (or neurilemmoma) is made up of proliferating Schwann cells of peripheral nerve sheaths. It is a neoplasm which occurs wherever schwann cells are present, that is in any myelinated peripheral nerve. In most cases, while schwannoma is sporadically manifested as a single benign neoplasm, the presence of multiple schwannomas in one patient is usually indicative of neuroÞ bromatosis 2 (NF-2) [ Fig. 3]. However, the term schwannomatosis or neurilemmomatosis has been used to describe patients with multiple non-vestibular schwannomas with no other stigmatas of NF-2 or NF-1. [10] Our two patients had isolated eyelid schwannoma with no family history or clinical Þ ndings of NF-1 or NF-2. Schwannoma is well known to develop in the orbit, constituting 1% of the orbital tumors in a series by Rootman et al. [11] Isolated cases have in 2 HIV positive men. J Clin Neuroophthalmol 1992;12:1-5.    been described in the conjunctiva, [1] the uveal tract, [2] and the sclera. [3] Its occurrence on the margin of the eyelid is extremely rare. In Pubmed database we only found eight published cases [ Table 1]. In our department of ophthalmology and in a period of 10 years, schwannoma represents 0.7% (2/282) of the eyelid neoplasms. In the López-Tizón series also schwannoma was rare and represented only 0.1% (2/2400) of eyelid neoplasms [8] Age range of published cases of eyelid Schwannomas was between seven and 70 years [ Table 1]. Clinically, the tumor is a solid, slowly

Pragya Parmar, Amjad Salman, M Rajmohan, Nelson CA Jesudasan
A 29-year-old woman who underwent laser in situ keratomileusis (LASIK) for myopic astigmatism in both eyes presented with severe pain, photophobia and decreased visual acuity in the left eye eight days aft er surgery. Examination revealed severe anterior uveitis with Þ brinous exudates in the anterior chamber, ß ap edema and epithelial bullae. Laboratory investigations for uveitis were negative and the patient required systemic and intensive topical steroids with cycloplegics to control the inß ammation. This case demonstrates that severe anterior uveitis may develop aft er LASIK and needs prompt and vigorous management for resolution. Laser in situ keratomileusis (LASIK) is currently the most popular method for the correction of low to moderate ametropia.
Information about anterior segment inß ammatory changes aft er LASIK is limited. While anterior uveitis has been described as a complication of LASIK with an incidence of 0.18%, [1] most reported cases so far have been those of mild to moderate uveitis that respond well to topical medication. [1,2] We report a patient who developed severe anterior uveitis with Þ brinous exudates in one eye eight days aft er undergoing LASIK for low myopic astigmatism in both eyes. Eight days aft er LASIK, the patient presented with severe pain, photophobia and decreased visual acuity in the left eye. Visual acuity at this time was 20/20 in the right eye and 20/80 in the left eye. Right eye examination was normal but the left eye showed mild ß ap edema, few peripheral epithelial bullae with intense ß are and cells in the anterior chamber with thick Þ brinous exudates in the anterior chamber. There were pigments on the endothelium and the anterior lens capsule but no keratic precipitates and the corneal stromal bed was clear. The intraocular pressure (IOP) was 11 mm Hg in the right eye and 9 mm Hg in the left eye. Posterior segment examination was normal in both eyes.

Case Report
The patient was started on hourly prednisolone acetate 1% eye drops (Predmet ® eye drops, Sun Pharmaceuticals, India) and cyclopentolate 1% eye drops three times daily (Cyclate eye drops ® , Cadila Pharamceuticals, India). As systemic examination progressive mass with no pain. Due to its rarity and unusual location, eyelid schwannoma is frequently clinically confused with other diagnoses like chalazion [5] (our Case 2), or inclusion cyst. [8] To avoid eventual recurrence, surgical excision is indicated and has to be complete.
Pathologically, schwannomas classically show a mixture of two patt erns, the Antoni Type A densely cellular patt ern and the Antoni Type B edematous and disorganized patt ern.
The most important feature for diagnosis remains the strong reactivity to S100 protein in immunochemistry. [1][2][3][4][5][6][7] Negativity of tumor cells for HMB45 rules out the diagnosis of melanotic lesion. [1] The rare occurrence of eyelid schwannoma should be kept in mind in the diff erential diagnosis of any solid palpebral lesion, especially in case of recurrent chalazion.
When they are isolated, they are mostly benign. In neurofibromatosis they might rarely undergo malignant transformation. [1]