Page 1325 - Clinical Small Animal Internal Medicine

138 Tumors of the Eye and Ocular Adnexa 1263

expected lifespan; the amount of discomfort due to the postoperative swelling and usually transient depigmen-
VetBooks.ir mass; and any financial constraints of the owner. All eye- tation of the frozen tissue are expected.
Tumors involving the conjunctiva and third eyelid
lid tumors, whether benign or malignant, may affect
vision or ocular comfort. Excision is indicated for all
eyelid tumors in cats, rapidly growing masses, those irri- (especially conjunctival hemangiosarcomas, melano-
mas, and third eyelid adenocarcinomas) are best
tating the eye or impairing eyelid function, if the owner treated by wide surgical excision, sometimes to the
is concerned, or the mass is cosmetically unappealing. In point of exenteration. Excision of the entire third eye-
young dogs, even large papillomas or histiocytomas that lid may result in keratoconjunctivitis sicca. Cryosurgery
are nonirritating may be monitored as spontaneous may allow the third eyelid to be spared in papillomas
regression is common. and early SCC. It can also be a useful adjunct to excision
Tumors involving less than one‐fourth to one‐third in advanced canine conjunctival melanomas and SCC.
of the palpebral fissure length are best treated by a Superficial keratectomy/sclerectomy, often followed
V‐plasty (wedge) or four‐sided (house) excision. In by cryosurgery, is preferred for many corneal and
the latter technique, the incision is made perpendicular scleral tumors, although some tumors require full‐
to the eyelid margin (rather than obliquely), resulting thickness corneal/scleral resection and placement of a
in superior apposition of the eyelid margins and donor graft.
greater wound stability, especially in larger tumors. It
may be possible to shrink large tumors that are
infected or inflamed with antibiotic or antiinflamma- Prognosis
tory therapy such that a wedge or four‐sided excision With treatment, the prognosis for most canine primary
becomes possible. Electrosurgical excision may result eyelid tumors is excellent. Even histologically malignant
in substantial scarring of the eyelids. Carbon dioxide primary lid tumors rarely metastasize, and recurrence
(CO 2 ) laser ablation may be appropriate for some rates are low. Recurrences, however, need to be differen-
smaller tumors. tiated from new primary eyelid tumors as these are com-
Tumors greater than one‐fourth to one‐third of the
eyelid typically require reconstructive blepharoplasty or mon. The prognosis for feline eyelid tumors is guarded,
as most eyelid tumors in cats are malignant. Conjunctival
other therapeutic modalities. Depending on tumor type, melanomas and adenocarcinomas of the third eyelid
alternative therapies include systemic chemotherapy frequently recur even if all clinically visible tumor is
(e.g., lymphoma, mast cell tumors), local infiltration with removed. Conjunctival hemangiosarcomas most likely
chemotherapeutic agents (e.g., SCC), and/or local radia- have a good prognosis because total excision may be
tion therapy (e.g., SCC). These modalities may com- curative, although recurrence and loss of the eye may
pletely eliminate the tumor or reduce it so that a less occur.
extensive surgical procedure is possible. Reconstructive
blepharoplasty, however, is the procedure of choice if
surgical cure is a possibility, other modalities are unlikely Limbal (Epibulbar) Melanoma
to substantially reduce the tumor, or if the tumor type
requires extensive margins. Limbal melanomas are typically benign, sessile, heavily
Liquid nitrogen cryosurgery may be an alternative pigmented masses originating from melanocytes in the
to extensive blepharoplasty for some eyelid and corneal limbal sclera or subconjunctival connective tissue of
tumors. It is fast, technically simpler than recon- middle‐aged dogs and cats. The majority are located in
structive blepharoplasty, and usually allows the the superior limbal region, suggesting that solar radia-
nasolacrimal puncta and canaliculus to be preserved. tion may be a risk factor. Growth is slow and confirmed
Often cryosurgery can be performed with only seda- metastasis has not been reported. Clinical signs are gen-
tion or local/topical anesthesia, which is helpful in erally mild and may include localized corneal invasion,
older or debilitated patients. After sedation/anesthesia, epiphora, and mild conjunctival irritation. Differential
the mass is isolated with chalazion forceps and diagnoses include conjunctival melanoma, uveal mela-
debulked flush with the lid margin. Using a closed noma invading the sclera, metastatic melanoma, and
probe that approximates the diameter of the mass as staphyloma or coloboma. Gonioscopy and ocular ultra-
much as possible, an iceball is formed and allowed to sound aid in differentiating invasive intraocular tumors
extend 3–5 mm beyond the visible margins of the from limbal melanomas.
mass in a double freeze‐thaw cycle. If the tumor is Therapy should be considered if the tumor has invaded
large, the iceballs should overlap. If complete regres- the eye, the animal is painful, or if growth is rapid.
sion is not achieved 2–3 weeks after the first session, Observation alone is often an appropriate approach in
additional treatments may be performed. Marked older dogs given the benign nature and usually slow