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

Rachel L. Davis1,2 | Philip A. Moore3 | Angela E. Ellis4

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..

Images

  • Figure 1. The left eye is depicted from the patient at the time of presentation. A well-circumscribed, pigmented, roughly circular, raised mass is present at the dorsonasal limbus extending into the cornea and sclera (scleral portion visible on excyclotorsion and abduction of the eye) measuring 8 x 9 mm. A crescent of corneal lipid is present at the leading edge of the mass. The ring flash artifact distortion is caused by the mass being raised off the globe surface.
  • Figure 2. The left eye is depicted from the patient 3 months after initial presentation and at the time that surgical excision was performed. The mass is raised, pigmented, well-circumscribed, and had grown substantially since initial presentation measuring 17 x 18 mm. There is a crescent of corneal lipid at the leading edge of the mass.
  • Figure 3. Schematic diagrams of the pinnal surgery site (a), limbal mass (b), cartilage surgery transplant (c), and conjunctival graft (d) are depicted. Figure A depicts the left pinna at the time of skin closure after harvesting of the central free cartilage graft. Two 20-mm linear connecting skin incisions were made 90 degrees to each other on the convex left central pinnal surface as depicted by the upside down ‘L’ in the diagram. After the skin was undermined from the cartilage and the cartilage plate was harvested as depicted by the dotted square, a Penrose drain was placed through the cartilage defect emerging through the dorsal and ventral portions of the skin incision and secured with 4-0 Ethilon on the convex surface as depicted by the two parallel lines to close the skin defect. Multiple-staggered vertical full-thickness simple interrupted pinnal sutures were placed with 4-0 Ethilon in the right pinna to prevent aural hematoma formation as depicted by the staggered hash lines in the diagram. (a). A penetrating sclerokeratoplasty was performed to excise a limbal-based OS mass as depicted in the diagram (b). The dotted line depicts the penetrating sclerokeratoplasty incision to remove the limbal melanoma. A split-thickness pinnal cartilage section was sutured into the full-thickness eyewall defect after limbal mass excision (c). Finally, a temporally harvested conjunctival graft was sutured to the leading edge of the temporal portion of the cartilage graft as depicted (d). The conjunctival graft was sutured temporally to the cornea and nasally directly to the cartilage graft as the conjunctival graft was not large enough to cover the entire transplant site due to the large size.
  • Figure 6. The left eye is depicted from the patient immediately postoperatively (a), fourteen days after surgery (b), five weeks after surgery (c), and 2 months after surgery (d). Immediately postoperatively (a), the eye is open and comfortable with pharmacologic mydriasis. The conjunctival graft is vascular and stable. Fourteen days after surgery (b), the conjunctival graft is vascular and becoming incorporated into the cornea. Five weeks after surgery (c), the conjunctival and pinnal grafts are fully incorporated into the cornea. The conjunctival pedicle has been trimmed from the dorsal region of the graft (arrow). Two months after surgery (d), the graft is stable and fully incorporated into the globe. The eye is visual and comfortable.

Keywords: canine, limbal melanoma dog, canine ocular melanoma surgery, penetrating sclerokeratoplasty dog, autologous pinnal cartilage graft dog eye, conjunctival grafting canine ophthalmology, corneoscleral grafting dogs, epibulbar melanoma Labrador retriever, dog eye tumor surgical treatment, veterinary ophthalmology limbal melanoma, canine corneal transplant alternative

1Animal Eye Clinic, Westfield, Indiana, USA
2Portland Veterinary Specialists, Portland, ME, USA
3Auburn University, Department of Clinical Sciences, College of Veterinary Medicine, Auburn, AL, USA
4Athens Veterinary Diagnostic Laboratory, University of Georgia, College of Veterinary Medicine, Athens, GA, USA

Correspondence:
Rachel L. Davis, DVM, MS, Diplomate, ACVO – Ophthalmologist

Animal Eye Clinic
4750 Killarney Drive
Carmel, IN 46033

Email: info@indyaec.com