Penetrating sclerokeratoplasty and autologous pinnal cartilage and conjunctival grafting to treat a large limbal melanoma in a dog

Abstract

A four-year-old neutered male Labrador retriever presented to Portland Veterinary Specialists Ophthalmology Service for evaluation of a pigmented mass oculus sinister (OS) of approximately 4-month duration. Complete ophthalmic examination revealed a large, pigmented, raised, well-demarcated, epibulbar mass appearing to originate from the nasodorsal limbal region. The mass was smooth and roughly circular, extending approximately 4 mm into the sclera and 14 mm into the nasodorsal cornea. Gonioscopy directly under the mass was not possible due to mass size. The visible iridocorneal angle was normal. High-resolution B-scan ultrasound showed mass extension to Descemet's membrane and deep sclera, but no intraocular invasion. Penetrating sclerokeratoplasty was performed followed by autologous pinnal cartilage and conjunctival grafting to repair the corneoscleral defect (20 mm x 19 mm) and to restore globe integrity and function. Histopathology confirmed the mass to be a benign limbal melanoma with complete excision. The surgery site healed without complication, and the pinnal cartilage became fully incorporated into the globe. Twelve months postoperatively, the patient remains visual with a normal intraocular and fundic examination. The pinnal harvest site on the right ear healed without complication. To the authors' knowledge, this is the first reported case of corneoscleral grafting using autologous pinnal cartilage. This may represent a viable alternative to other corneoscleral grafting procedures for large defects and is an attractive treatment option due to lack of host rejection, readily available source of donor cartilage, and provision of tectonic support to the globe.

Deep lamellar keratectomy and penetrating scleroplasty using CO2laser photoablation and bimodal grafting for the treatment of a limbal melanoma in a dog

“…En bloc resection of limbal melanomas is generally regarded as the ideal surgical technique to most reliably prevent tumor regrowth; however, this approach requires concurrent grafting procedures and can be associated with more severe complications including marked uveitis, dyscoria, extensive intraocular hemorrhage, and cataract formation . Partial‐thickness resection of limbal masses is commonly combined with adjunctive procedures used to cause necrosis of remaining neoplastic cells such as cryotherapy, photocoagulation, and plesiotherapy …”

“…Over the last several decades, numerous surgical approaches have been described for the resection of limbal melanomas, including full-or partial-thickness resection and various grafting procedures with or without adjunctive treatments including cryotherapy, plesiotherapy, and diode or Nd:YAG laser photocoagulation. 4,[6][7][8][9][10][11][12][13] To the authors' knowledge, this is the first clinical report to describe the surgical resection of a limbal melanoma by way of penetrating scleroplasty using exclusively CO 2 laser photoablation. The deep lamellar keratectomy and conjunctival advancement were routinely performed as described in the literature.…”

“…Limbal (epibulbar) melanomas are typically benign neoplasms originating from the melanocytes at the corneoscleral junction and must be differentiated from uveal melanomas with extrascleral extension. Some debate still exists in the veterinary literature whether the proper nomenclature of “melanocytoma” or “melanoma” is the most appropriate classification of these tumors . Clinically, canine limbal melanomas are well‐circumscribed, slightly raised, heavily pigmented masses most commonly arising from the dorsotemporal limbus that may affect the cornea, conjunctiva, and/or sclera …”

“…Some debate still exists in the veterinary literature whether the proper nomenclature of "melanocytoma" or "melanoma" is the most appropriate classification of these tumors. 1,3,4 Clinically, canine limbal melanomas are well-circumscribed, slightly raised, heavily pigmented masses most commonly arising from the dorsotemporal limbus that may affect the cornea, conjunctiva, and/or sclera. [5][6][7][8] There appears to be a breed predilection for limbal melanoma development most commonly affecting Golden Retrievers, Labrador Retrievers, and German Shepherds.…”

“…1,2,5 A number of surgical techniques have been described in the veterinary literature which include lamellar or penetrating sclerokeratoplasty with various replacement grafting procedures, and partial resection modalities combined with cryotherapy, strontium-90β plesiotherapy, and diode laser photocoagulation. 4,[6][7][8][9][10][11][12][13] This report describes the surgical treatment of a limbal melanoma in a dog by a deep lamellar keratectomy and penetrating scleroplasty using sharp lamellar dissection and CO 2 laser photoablation, followed by reconstruction of the corneoscleral defect using both a double-layered biosynthetic graft and conjunctival advancement flap.…”