Thursday, December 23, 2010

Squamous Cell Carcinoma

Signs and Symptoms
Squamous cell carcinoma is the second most common malignant eyelid neoplasm in the United States, after basal cell carcinoma.

It is most often encountered in elderly, fair-skinned individuals who have a history of chronic sun exposure. Patients presenting with this lesion may demonstrate a roughened scaly patch of tissue on or near the lid margin or in the canthal region. The area is typically red, elevated and nodular, with crusted and/or bloody margins. Often, patients describe this lesion as “a non-healing scab.” According to one study, the most common presentation involves nodular ulceration as the disease progresses, resulting in hemorrhagic or purulent discharge.

Squamous cell carcinoma in its early stages is easily confused with a multitude of other eyelid lesions, both malignant and benign. Some of these lesions include basal cell carcinoma, sebaceous gland carcinoma, follicular keratosis, actinic keratosis, seborrheic keratosis, and keratoacanthoma.

Rarely are patients with squamous cell carcinoma symptomatic, displaying only mild irritation in most cases. Acuity is not affected unless the lesion is so large as to obscure the visual axis.

Squamous cell carcinoma is a potentially invasive tumor derived from surface epithelium. In the early stages, the normal epithelial cells are replaced by atypical squamous cells throughout the epidermis, resulting in a loss of normal maturation. This stage is sometimes referred to as squamous cell carcinoma in situ. After the dysplastic squamous cells encroach beyond the borders of the basement membrane, the lesion is referred to as invasive squamous cell carcinoma.

While no single causative agent for the development of squamous cell carcinoma has been identified, it is clear that ultraviolet radiation is a substantial risk factor and demonstrates a distinct association with this disease. This is supported by the fact that the majority of squamous cell tumors arise on the lower lid margin and medial canthus, the two periocular areas most susceptible to sunlight exposure. Increasing age and northern European descent are two other commonly associated factors in patients with squamous cell carcinoma.

The management of squamous cell carcinoma is virtually identical to that of basal cell carcinoma of the lid. These lesions may be treated with surgical excision, radiation therapy, chemotherapy, or cryotherapy. The preferred course for most cases is surgery, with broad margins to ensure complete removal. Frozen tissue sections of the tumor borders are evaluated intraoperatively to further assure that the lesion is excised completely (Mohs micrographic technique). This method offers the greatest success with the least incidence of recurrence. Local radiation and/or systemic chemotherapy may be used in managing squamous cell carcinoma when surgery is intolerable or refused by the patient. Both of these modalities carry significant side effects, and neither is as efficacious as surgical intervention. Cryotherapy has been used somewhat effectively for smaller tumors, but does not ensure complete tumor eradication, and therefore results in a high recurrence.

Clinical Pearls

Squamous cell carcinoma represents approximately
5 percent of all eyelid malignancies. While this particular neoplasm does possess the ability to invade local tissues and metastasize to other organ systems, it is not a particularly aggressive tumor. Its rate of development is quite slow, and metastasis is exceedingly rare. Still, the potential for damage exists in cases where diagnosis and treatment are delayed.
Early biopsy is often the key to diagnosis. Suspicious lid lesions, which demonstrate irregular growth, changes in color or appearance, or discharge of a purulent or bloody nature should be biopsied to rule out cancerous entities. Confirmed malignancies should be referred promptly for treatment by an oculoplastics specialist or, where possible, an ocular oncologist.

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