Eyelid Tumors in Dogs
Dr. Noelle McNabb
Complete medical history and physical examination including palpation of regional lymph nodes for evidence of enlargement and auscultation of the chest. Historically, it is important to ascertain the duration of the eyelid lesion, the occurrence of any prior tumors (anywhere in the body), and any accompanying physical symptoms of disease.
Diagnostic tests are performed to determine the cause for the eyelid nodule/swelling, verify that the lesion is of a specific tumor type, define the degree of local invasion of the tumor, and determine if the eyelid tumor will spread. The following tests are often recommended:
Complete ophthalmic examination includes close examination of the eyelids, cornea, conjunctiva, and front chamber of the eye. This examination helps to delineate the boundaries and local extent of the eyelid tumor. The conjunctiva and cornea are examined for evidence of irritation caused by the eyelid tumor.
Fluorescein staining of the cornea is performed to assess the presence of corneal erosions and ulcerations.
Bacterial culture of secretions from the eye may be done to determine the presence and type of bacteria.
Fungal culture and microscopic examination of skin scrapings from around the eyelid are done to assess for the presence of ringworm and parasitic mites.
Fine needle aspirate of the eyelid tumor for cytology (complete cell analysis) can, in some cases, help to classify the type of tumor. Because cells are difficult to retrieve in some tumors, this test may be inconclusive.
Tissue biopsy of the eyelid tumor provides the best means to establish a definitive diagnosis of the tumor type.
Complete blood count and serum biochemistry are done to evaluate organ functions and to search for evidence of infection or certain types of malignant cancers such as lymphosarcoma.
Cytology of cell aspirates from enlarged regional lymph nodes may be considered
to assess for the presence of tumor metastasis.
Thoracic (chest) and abdominal radiographs are performed to determine the presence and extent of tumors that are suspected to have spread from somewhere else in the body.
With respect to treatment eyelid tumors may be divided into two types, those that can be managed with medicines and those that require surgery. Most eyelid tumors in dogs require surgery, and the surgery may be followed by the application of certain topical medications.
In the early stages of eyelid tumor development, clinical evidence of eye discomfort or irritation is often not evident. Invariably, as eyelid tumors enlarge, they result in irritation to the surface of the eye and interfere with adequate blinking resulting in discharge from the eye. The irritation caused by enlarging eyelid tumors may be difficult to treat medically until the eyelid tumor can be treated and removed surgically.
Certain types of eyelid tumors may respond to medical therapy, especially if the growth is small or too invasive to excise completely. Small mast cell tumors (mastocytomas) and certain histiocytomas may respond to systemic or locally injected corticosteroids.
Lymphosarcoma (LSA) in the eyelid often represents metastatic (spread of the disease) from somewhere else in the body. In early stages of eyelid/conjunctival LSA, chemotherapy may reduce the size of the tumor regression and cause remission in some animals. However, response to chemotherapy is unpredictable and dependent on numerous factors.
Response to medical therapy for all other eyelid tumors is poor. This is in contrast to some forms of inflammation of the eyelids, which often respond well to various medications.
The recommended treatment for most canine eyelid tumors is surgical removal. This can be accomplished with either surgical excision using a scalpel or via laser surgery. Eyelid tumor removal with surgical excision is the preferred method for two reasons. First, the margins of the excised piece of tissue containing the tumor can be examined microscopically to ensure that they are free of tumor cells and that tumor excision was complete. Second, precise surgical closure of the eyelid incision is best accomplished with sutures.
In contrast, laser therapy to remove eyelid tumors vaporizes the tumor, and a biopsy specimen cannot easily be obtained for examination. Surgical margins cannot be evaluated after laser therapy, and precise closure of the incision does not always occur, so there is greater scarring of the eyelid. Diode or carbon dioxide lasers can be used successfully to treat small eyelid tumors that ideally do not involve the eyelid margin, and are most effective on tumors that contain pigment.
Complete excision of most benign eyelid tumors in the dog is usually curative.
Extensive plastic and reconstructive surgery may be necessary following the removal of very large tumors. Maintaining a continuous eyelid margin and mobile upper eyelid are paramount to maintaining ocular health and vision. As a general guideline, eyelid margin tumors that involve greater than 1/3 of the total length of either the upper or lower eyelid prevent simple removal of the tumor and necessitate performing reconstructive surgeries. It is not uncommon for major reconstructive surgeries to be performed in stages, with at least two separate surgical events.
Certain types of tumors may respond to cryotherapy, which is freezing of the tumor. This therapy may be considered for the benign meibomian gland tumors, benign melanocytomas, invasive histiocytomas, some small mast cell tumors, small and confined squamous cell carcinomas, and selected other tumors.
Some eyelid tumors are too large or extensive to remove surgically, and enucleation or removal of the eye is necessary. Advanced eyelid tumors may extend into the soft tissues behind the eye (into the orbit) or into the eye.