Page 1329 - Problem-Based Feline Medicine

65 – THE CAT WITH ABNORMAL EYELID APPEARANCE 1321

may be present. The lesion may invade into adjacent
EYELID NEOPLASIA (SQUAMOUS CELL
CARCINOMA, BASAL CELL CARCINOMA, palpebral conjunctiva. These neoplasms generally only
MAST CELL TUMOR, FIBROSARCOMA, AND occur in non-pigmented skin.
SEBACEOUS GLAND ADENOMA OR Basal cell carcinomas are usually round and well cir-
CARCINOMA)**** cumscribed, but can become ulcerated. Appear as flat
to slightly raised areas of red to dark brown discol-
Classical signs oration with irregular edges.
● Localized or diffuse eyelid swelling. Mast cell tumors can form either well or poorly cir-
● Ulceration, excoriation or discharging cumscribed areas of swelling in the eyelid. They appear
sinuses. as rapidly growing nodular tumor, often with poorly
● Altered tissue color. defined borders, and variable surface ulceration.
Fibrosarcomas are generally focal nodular neoplasms
Pathogenesis in the subcutis, but can become ulcerated. Usually
appear as a rapidly growing diffuse swelling, and
Squamous cell carcinoma is thought to be induced by
involve adjacent facial or orbital tissues.
prolonged exposure to solar radiation. This causes dys-
plastic changes in the surface squamous cells of lid Sebaceous gland adenomas or carcinomas are seen as
epithelium, with eventual progression of the dysplasia a nodular or diffuse mass causing localized thickening
to invasive carcinoma. This neoplasm almost exclu- of the eyelid. The tumor may have an ulcerated surface.
sively affects non-pigmented skin, so is more com-
mon in white cats. It is the most common feline eyelid
Diagnosis
neoplasm.
Tentative diagnosis is based on the appearance of the
Basal cell carcinoma arises from the basal cells of the
eyelid lesion.
epithelium. Solar radiation is a possible etiology. The
tumor is less common. Exfoliative cytology is useful in some cases that show
ulceration.
Mast cell tumor is a neoplastic proliferation of mast cells
● Squamous cell carcinomas typically appear as
in tissue. Inciting factors are unknown. Less common.
undifferentiated, single or grouped, round to square
Fibrosarcomas arise from connective tissue fibroblasts cells with large amounts of light basophilic cytoplasm
of the dermis or subcutis. Feline sarcoma virus (FeSV) and pleomorphic nucleolated nuclei. Sometimes
is implicated as a cause of multicentric fibrosarcoma in more squamous, partly or fully keratinized cells can
young cats. Less common. be seen.
● Basal cell carcinomas are usually more basophilic
Sebaceous gland adenomas or carcinomas are rare.
staining than SCC. Cells are more round to square
than SCC, and have small amounts of basophilic
Clinical signs cytoplasm, and relatively uniform round to oval,
non-nucleolated nuclei.
Any of the following typical signs might be seen includ-
● Mast cell tumors can be poor- to well-differenti-
ing localized or diffuse areas of eyelid swelling, ero-
ated with intensely basophilic staining cytoplasmic
sion, crusting, discharging sinuses (+/- necrotic
granules, and small, round, centrally located nuclei.
material forming a core), or alterations in tissue color.
Accompanying eosinophils are usually seen.
Squamous cell carcinoma can have a flattened ver-
Fine-needle biopsy can be useful in cases where there
rucous (cauliflower-like) appearance or can look
is discreet swelling.
erosive without swelling. Often there is ulceration and
crusting affecting the lid margins and non-haired skin Definitive diagnosis is based on histopathological
or conjunctiva. Localized or diffuse eyelid swelling examination of affected tissue.