Ocular Squamous Cell Carcinoma (2023)

Chapter 149

Elizabeth A. Giuliano

Tumors affecting the orbit, eyelid, or globe often manifest initially as signs of ocular discomfort or mucopurulent discharge, but they can be identified before the development of serious ocular or periocular complications through careful ophthalmic examination. Squamous cell carcinoma (SCC) is the most common neoplasm of the equine eye and ocular adnexa and is the second most common tumor affecting the horse overall. Squamous cell carcinoma may involve any or all of the corneoconjunctiva, bulbar conjunctiva, third eyelid, and eyelids. The biologic behavior of SCC varies depending on location. Tumors are typically locally invasive and slow to metastasize. Metastasis to local lymph nodes, salivary glands, and thorax can occur. A poorer prognosis has been associated with SCC involving the eyelid, compared with SCC of the nictitating membrane, nasal canthus, or limbus.

Several risk factors have been associated with development of SCC. Ultraviolet light exposure is believed to play an important role in the pathogenesis of SCC inhorses and other species. Exposure to ultraviolet light can lead to mutations in the p53 gene, an important regulator of cell growth and proliferation, with resulting development of SCC. Additionally, a breed predilection exists for draft horses, Appaloosas, and American Paint Horses. Finally, a higher frequency of ocular SCC has been reported in horses lacking pigmentation around the eye, such as Pintos.

Examination and Diagnostic Procedures

Given the sometimes slow-growing nature of ocular SCC and the overall small area this tumor may occupy, compared with the total body surface area of a horse, this neoplasm is often not detected by the owner or general practitioner until it is advanced. For this reason, it is recommended that the equine practitioner perform a complete ophthalmic examination as part of any routine health check or prepurchase examination. When presented with any ophthalmic abnormality, preservation of vision and ocular comfort should guide the diagnostic and therapeutic plan.

(Video) Ophthalmology Series : Ocular Surface Squamous Neoplasia (OSSN)

The horse should first be examined from a distance to facilitate assessment of facial symmetry and eyelash positioning. One of the first clinical signs observed with ocular pain in horses is ventral deviation of the eyelashes on the affected side. The regional lymph nodes and parotid salivary glands should be palpated. A room with controlled lighting is ideal for examination of the globe and periocular structures and should be used for any animal ophthalmic exam; however, access to adjustable lighting is not always possible in equine practice. A dark blanket placed over the examiner’s and horse’s heads helps create a darkened environment. The complete ophthalmic examination and derivation of a minimum ophthalmic database should be undertaken during all ophthalmic examinations with few exceptions. Components of the minimum ophthalmic database include menace response, direct and consensual pupillary light reflex, palpebral reflex, Schirmer tear test, fluorescein stain, and tonometry (Box 149-1). Tonometry must be performed with caution in any horse with a deep corneal ulcer to avoid globe perforation. Retropulsion and assessment of ocular motility are often helpful in horses with suspected orbital tumors or intraocular tumors with extrascleral extension. Retropulsion also enables the practitioner to more thoroughly examine the third eyelid (nictitans), a common site for SCC in horses. To better determine prognosis and plan treatment, gentle digital palpation of the orbital rim is essential. This is best accomplished with the horse sedated. Using a gloved finger lubricated with a small volume of ophthalmic ointment, the examiner inserts the finger into the conjunctival fornix and palpates the entire orbital rim through the mucosa of the upper and lower fornices. When SCC has invaded local surrounding tissues, the orbital rim often cannot be felt in areas of neoplastic infiltration.

Box 149-1

Key Components of a Complete Ophthalmic Examination for Horses With Squamous Cell Carcinoma*

*The examination should be performed in the order listed during both a diagnostic examination and evaluations to assess response to treatment.

After a complete ophthalmic examination has been performed, diagnostic imaging may be indicated, such as ocular ultrasound, skull radiographs, and computed tomography or magnetic resonance imaging. These modalities are especially helpful in horses with SCC in which evidence of bony extension is likely to alter the prognosis or surgical planning. Fine-needle aspiration of the regional lymph nodes, parotid salivary gland, or both should be performed when lymphadenopathy is detected or if there is local invasion of tumor. Definitive diagnosis of SCC should always be obtained on the basis of biopsy and histologic diagnosis. Consultation with or referral to a veterinary ophthalmologist may be helpful. Members of this specialty group can easily be located at www.acvo.org.

(Video) Surgical Resection of Conjunctival Squamous Cell Carcinoma using the "No Touch" Technique

Clinical Features of Ocular and Periocular Squamous Cell Carcinoma

Clinical features of SCC and its precursor lesions, which include actinic keratosis, epithelial dysplasia, chronic keratosis, and carcinoma in situ, are variable. Although SCC may arise from any location on the globe or periocular tissues, commonly affected sites include the temporal region of the limbus, leading edge of the nictitans, and eyelid margins. Classic features of this tumor type include pink to white, raised, friable, vascularized lesions with a cobblestone- or cauliflower-like appearance (Figures 149-1 to 149-4). Necrotic tumor surfaces with a white “cake frosting” appearance from secondary bacterial infection may impart a fetid odor to the lesion.

Ocular Squamous Cell Carcinoma (1)

Ocular Squamous Cell Carcinoma (2)

Ocular Squamous Cell Carcinoma (3)

Ocular Squamous Cell Carcinoma (4)

Proliferative SCC arising from the eyelid and nictitans may be pedunculated with a broad base (see Figure 149-3). Ulcerated forms of this tumor typically cause erosion of the eyelid margins, medial canthus, or nictitans (see Figure 149-4). Both proliferative and ulcerated forms of SCC may be present concurrently. If left untreated, local orbital invasion can ensue (Figure 149-5), resulting in substantial ocular discomfort and necessitating exenteration, which is removal of the orbital contents and eyelids. Differential diagnoses for SCC include papilloma, habronemiasis, eosinophilic conjunctivitis, foreign body granuloma, amelanotic melanoma, cutaneous mastocytoma, and other causes of blepharitis or keratoconjunctivitis. Although most SCCs have the described typical appearance at initial evaluation, definitive histologic diagnosis should always be obtained.

Ocular Squamous Cell Carcinoma (5)
(Video) VMX 2018 Ocular Squamous Cell Carcinoma What to Do


Ocular and periocular tumors in horses represent a unique therapeutic challenge to equine practitioners as a consequence of both anatomic location and the unique characteristics of SCC. Reconstructive surgery to remove extensive masses affecting the globe or adnexa while maintaining cosmesis and vision is challenging and, at times, impossible. The eye is a delicate organ and is prone to visual compromise from secondary inflammation. Special instrumentation coupled with skill in microsurgical techniques is needed for removal of corneal or conjunctival masses with the best chance for a visual outcome. Eyelids act as the pri­mary “windshield wiper” of the cornea, and, as such, any irregularity in eyelid shape or contour can result in chronic keratitis, ulceration, and discomfort. Preservation of eyelid function must be balanced with the need for adequate tumor resection. Eyelid tumors in horses are often not amenable to complete excision. Eyelid reconstruction surgery, such as the H-plasty or bucket-handle procedures commonly performed in small animals, is nearly impossible in horses because of the tight adherence of periocular skin to underlying fascia and bone.

Tumor characteristics also play a role in treatment outcome for SCC. Surgical excision alone for ocular or periocular SCC carries a high recurrence rate and often results in incomplete tumor resection if the mass is larger than 1cm in diameter. For this reason, veterinary ophthalmologists rarely recommend sharp dissection alone. Various ancillary treatments have been reported, including cryosurgery, hyperthermia, chemotherapy, radiotherapy, immunotherapy, and laser ablation (Table 149-1). Reported success rates vary, and the published literature on ophthalmic SCC in horses includes many reports with low case numbers and poor long-term follow-up. Additionally, the extent of tumor involvement is not always well characterized, leading to publication of unrealistically positive outcomes in some studies that included cases with superficial tumors for which virtually any type of treatment may have yielded favorable results.


What causes squamous cell carcinoma of the eye? ›

SCC has various risk factors and etiologies including aging, longstanding ultraviolet radiation exposure, oil derivates and arsenic exposure , cigarette smoke exposure, Human Papilloma Virus infection (HPV), Human Immunodeficiency Virus infection (HIV), xeroderma pigmentosum, actinic keratosis (AK), squamous ...

What is the survival rate for squamous cell carcinoma? ›

In general, the squamous cell carcinoma survival rate is very high—when detected early, the five-year survival rate is 99 percent. Even if squamous cell carcinoma has spread to nearby lymph nodes, the cancer may be effectively treated through a combination of surgery and radiation treatment.

What does squamous cell carcinoma of the eye look like? ›

Conjunctival Squamous Cell Carcinoma is a cancer on the surface of the eye and is usually found in older Caucasian (white skinned) patients. It appears as a white or yellow-pink nodule on the eye surface in the front of the eye where it can easily be seen.

Can you live a long life with squamous cell carcinoma? ›

Most (95% to 98%) of squamous cell carcinomas can be cured if they are treated early. Once squamous cell carcinoma has spread beyond the skin, though, less than half of people live five years, even with aggressive treatment.

How serious is squamous cell carcinoma in the eye? ›

Squamous cell carcinoma of the conjunctiva is the end-stage of a spectrum of disease referred to as ocular surface squamous neoplasia (OSSN). OSSN is a malignant disease of the eyes that can lead to loss of vision and, in severe cases, death.

Should I worry if I have squamous cell carcinoma? ›

Squamous cell carcinoma of the skin is usually not life-threatening, though it can be aggressive. Untreated, squamous cell carcinoma of the skin can grow large or spread to other parts of your body, causing serious complications.

Is squamous cell carcinoma ever fatal? ›

Cutaneous squamous cell carcinoma is usually easily treated with surgery; however, a subsection of patients with specific disease risk factors are more likely to develop metastases and die from the disease, according to the results of a study published in JAMA Dermatology.

What kills squamous cell carcinoma? ›

Chemotherapy. Chemotherapy uses powerful drugs to kill cancer cells. If squamous cell carcinoma spreads to the lymph nodes or other parts of the body, chemotherapy can be used alone or in combination with other treatments, such as targeted drug therapy and radiation therapy.

Is squamous cell carcinoma fully curable? ›

Most squamous cell carcinomas (SCCs) of the skin can be cured when found and treated early. Treatment should happen as soon as possible after diagnosis, since more advanced SCCs of the skin are more difficult to treat and can become dangerous, spreading to local lymph nodes, distant tissues and organs.

How long does it take for squamous cell carcinoma to spread? ›

Metastasis of cutaneous squamous cell carcinoma (cSCC) is rare. However, certain tumor and patient characteristics increase the risk of metastasis. Prior studies have demonstrated metastasis rates of 3-9%, occurring, on average, one to two years after initial diagnosis [6].

What are the warning signs of squamous cell carcinoma? ›

What are the signs and symptoms of squamous cell carcinoma?
  • Rough, reddish scaly patch.
  • Open sore (often with a raised border)
  • Brown spot that looks like an age spot.
  • Firm, dome-shaped growth.
  • Wart-like growth.
  • Tiny, rhinoceros-shaped horn growing from your skin.
  • Sore developing in an old scar.

What does stage 1 squamous cell carcinoma look like? ›

Squamous cell carcinoma initially appears as a skin-colored or light red nodule, usually with a rough surface. They often resemble warts and sometimes resemble open bruises with raised, crusty edges. The lesions tend to develop slowly and can grow into a large tumor, sometimes with central ulceration.

Can squamous cell carcinoma spread to the brain? ›

Squamous cell carcinomas are defined as relatively slow-growing malignant (cancerous) tumors that can spread (metastasize) to surrounding tissue if left untreated. Squamous cell carcinoma may spread to the sinuses or skull base, or other areas of the brain.

What is the most common cause of squamous cell carcinoma? ›

The cause of most squamous cell carcinoma (SCC) of the skin is well known. People usually develop this skin cancer because ultraviolet (UV) light has badly damaged their skin. Most UV light comes from: The sun.

Which is worse melanoma or squamous cell carcinoma? ›

Of the three main types of skin cancer, melanoma is most deadly, and basal cell, most common. Squamous cell cancer falls in between. It's three times as common as melanoma (some 200,000 new cases each year versus 62,000).

Which squamous cell carcinoma has best prognosis? ›

Patients with stage I, II, or III cancer have the best survival, whereas patients with stage IV or recurrent cancer who are older than 66.5 years have the worst survival. Patients with stage IV or recurrent cancer who are younger than 66.5 years have intermediate survival.

Does squamous cell carcinoma need to be removed? ›

Basal or squamous cell skin cancers may need to be removed with procedures such as electrodessication and curettage, surgical excision, or Mohs surgery, with possible reconstruction of the skin and surrounding tissue. Squamous cell cancer can be aggressive, and our surgeons may need to remove more tissue.

What is the life expectancy for ocular melanoma? ›

The 5-year survival rate for eye melanoma is 82%. When melanoma does not spread outside the eye, the 5-year relative survival rate is about 85%. The 5-year survival rate for those with disease that has spread to surrounding tissues or organs and/or the regional lymph nodes is 71%.

What age group is most affected by squamous cell carcinoma? ›

Age over 50: Most SCCs appear in people over age 50. Fair skin: People with fair skin are at an increased risk for SCC. Gender: Men are more likely to develop SCC. Sun-sensitive conditions including xeroderma pigmentosum.

What does Stage 4 squamous cell carcinoma look like? ›

Symptoms of stage 4 squamous cell carcinoma usually begin with some kind of skin lesion or growth. Often, the tumors of squamous cell carcinoma look like a scaly red patch of skin that won't heal. These tumors are often crusty and raised, and they may cause sores or ulcers that last for several weeks.

Which is the considered highest risk site in squamous cell carcinoma? ›

The sun-exposed head and neck are the most frequent sites for these cancers to arise and in most patients diagnosed with a cutaneous squamous cell carcinoma, local treatment is usually curative. However, a subset is diagnosed with a high-risk cutaneous squamous cell carcinoma.

Is squamous cell carcinoma the worst? ›

Although squamous cell carcinoma can be more aggressive than basal cell cancer, the risk of this type of cancer spreading is low—as long as the cancer is treated early, Dr. Leffell says.

How long is chemotherapy for squamous cell carcinoma? ›

Applied by a patient at home over the course of approximately three to six weeks.

Where does squamous cell carcinoma usually spread to? ›

Squamous cell cancers can metastasize to nearby lymph nodes or other organs, and can invade both small and large nerves and local structures. Biopsy can help determine if the squamous cell cancer is a low-risk tumor or a high-risk tumor that requires more aggressive treatment.

What foods fight squamous cell carcinoma? ›

Food That Lower Your Skin Cancer Risk

Vitamin C – Citrus fruits, strawberries, raspberries, broccoli, bell peppers, and leafy greens. Vitamin D and Omega-3 fatty acids – Fatty fish, like mackerel, sardines, herring, tuna, and salmon. Vitamin D – Milk, cheese, and vitamin D-fortified orange juice.

What organs does squamous cell carcinoma affect? ›

If left untreated, squamous cell carcinoma can spread to nearby lymph nodes, bones or distant organs (such as the lungs or liver). Normal squamous tissue usually appears flat. When this tissue develops cancer it can appear as round masses that are can be flat, raised, or ulcerated.

What is considered early detection of squamous cell carcinoma? ›

The key warning signs are a new growth, a spot or bump that's getting larger over time, or a sore that doesn't heal within a few weeks. (See Signs and Symptoms of Basal and Squamous Cell Skin Cancer for a more detailed description of what to look for.)

Is Stage 4 squamous cell carcinoma fatal? ›

The 5-year survival is 99 percent when detected early. Once SCC has spread to the lymph nodes and beyond, the survival rates are lower. Yet this cancer is still treatable with surgery and other therapies, even in its advanced stages.

Does squamous cell carcinoma spread slow? ›

Squamous cell carcinoma rarely metastasizes (spreads to other areas of the body), and when spreading does occur, it typically happens slowly. Indeed, most squamous cell carcinoma cases are diagnosed before the cancer has progressed beyond the upper layer of skin.

What happens if you don't remove squamous cell carcinoma? ›

Leaving Squamous Cell Carcinoma Untreated

This is potentially life threatening and is most dangerous when found on the face, lips, ears or neck. As it grows, there is the chance it may spread to the lymph nodes and internal organs, and while it isn't as fast growing as melanoma, it still requires treatment.

Where does squamous cell carcinoma spread first? ›

Hanke: The first place SCCs metastasize to is the regional lymph nodes. So if you have a squamous cell carcinoma on your cheek, for example, it would metastasize to the nodes in the neck. But there are treatments for that. Patients can have surgery, radiation and, in some advanced cases, immunotherapy medication.

What is Stage 3 squamous cell carcinoma? ›

More Information. Stage IIIA squamous cell carcinoma of the esophagus. Cancer has spread into the mucosa layer, thin muscle layer, or submucosa layer of the esophagus wall. Cancer is found in 3 to 6 lymph nodes near the tumor; OR cancer has spread into the thick muscle layer of the esophagus wall.

Can stress cause squamous cell carcinoma? ›

Stress and Skin Cancer

However, stress may also play a role, as it causes the body to produce unstable oxygen molecules called free radicals. Those can increase inflammation and damage your skin's DNA, leading to mutations and, possibly, skin cancer.

What are high risk features of squamous cell carcinoma? ›

High-risk features are depth of invasion (>2 mm), poor histological differentiation, high-risk anatomic location (face, ear, pre/post auricular, genitalia, hands, and feet), perineural involvement, recurrence, multiple cSCC tumors, and immunosuppression.

Is Stage 2 squamous cell carcinoma curable? ›

Unfortunately, there's no definite cure for stage 2 squamous cell carcinoma. However, if it's caught at stage 2, treatments for the disease are often quite successful.

What is the average size of squamous cell carcinoma? ›

Stage 1 squamous cell carcinoma: In stage 1, the cancer is less than 2 centimeters, about 4/5 of an inch across, has not spread to nearby lymph nodes or organs, and has one or fewer high-risk features.

Can SCC turn into melanoma? ›

Squamous cell cancer cannot turn into melanoma since each type of cancer arises from different types of cells in the skin. It is possible, however, to have both squamous cell skin cancer and melanoma skin cancer at the same time.

Can squamous cell carcinoma become other cancers? ›

Abstract. Epidemiological studies suggest that individuals with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) of the skin are more likely to develop other malignancies; however, the factors responsible for this are unknown.

Which skin cancers has poorest prognosis? ›

Non-melanoma skin cancer that has spread to other parts of the body (called distant metastases) has a very poor prognosis.

Is squamous cell carcinoma benign or malignant? ›

Squamous cell carcinoma (SCC) is an epithelial malignancy involving many anatomical sites and is the most common cancer capable of metastatic spread. Development of early diagnosis methods and novel therapeutics are important for prevention and mortality reduction.

Are eye cancers genetic? ›

Intraocular melanoma can run in families, although it is rare. Usually, it is due to a mutation or change in a gene called BAP1, which is mostly linked with metastatic uveal eye cancer. This gene change is also seen in other cancer types, such as kidney cancer and mesothelioma.

What are the most common primary cancers that metastasize to the eye? ›

The most common sources of ocular metastasis are breast cancer (primarily in women) followed by lung cancer (more commonly in men).

What is eye carcinoma symptoms? ›

Symptoms of eye cancer

shadows, flashes of light, or wiggly lines in your vision. blurred vision. a dark patch in your eye that's getting bigger. partial or total loss of vision.

Are eye cancers rare? ›

Eye cancer is rare. In fact, there are only about 3,500 new cases a year, a fraction of the estimated 1.7 million-plus cases of cancer that are diagnosed in the U.S. each year. There are often no early symptoms or warning signs, especially if the cancer is small and not located close to the vital structures of the eye.

How common are eye cancers? ›

The American Cancer Society's estimates for eye cancer in the United States for 2022 are: About 3,360 new cancers (mainly melanomas) of the eye and orbit (1,790 in men and 1,570 in women) About 410 deaths from cancers of the eye and orbit (220 in men and 190 in women)

How long does it take for ocular melanoma to metastasize? ›

Some estimates suggest that in 40-50% of individuals, an ocular melanoma will metastasize. Based on the aggressiveness of the particular tumor, as defined by clinical and genetic features, metastasis may be detected as early as 2-3 years after diagnosis and rarely as late as decades after treatment.

Is the most common ocular tumor in adults? ›

Choroidal melanoma is the most common primary adult ocular malignancy.

What does a tumor in the eye look like? ›

At first, you may see an abnormal brown spot on or in your eye. It's called a nevus. These moles usually form on the choroid, iris, or conjunctiva of the eye. An eye tumor may look like a dark spot on the colored part of your eye called the iris.

Is eye tumor curable? ›

There are various ways to treat eye tumors, depending on the diagnosis, size and aggressiveness of the tumor, and other factors. Certain small tumors may respond to laser treatment or freezing (cryosurgery). In some instances, it is possible to remove a tumor surgically and still preserve vision.

How long can you live with eye tumor? ›

The 5-year survival rate for people with eye cancer is 80%. If the cancer is diagnosed at an early stage, the 5-year survival rate is 85%. About 73% of people are diagnosed at this stage. However, survival rates depend on the size and location of the tumor and the type of cancer diagnosed.

Is eye biopsy painful? ›

After you have the local or general anaesthetic, the specialist puts a thin needle attached to a syringe into your eye. They draw out some cells from the tumour. This usually takes a few minutes. If you have a local anaesthetic you may be aware of something going on, but you shouldn't have discomfort or pain.

Can you drive a car with only one eye? ›

Sight in one eye only

It may take up to three months for you to adapt safely to driving with one eye, be prepared for this. In particular your ability to judge distances accurately may be affected and you may not be aware of objects to either side of you.


1. No Touch Technique: Conjunctival Squamous Cell Carcinoma Resection
(D. Brian Kim MD)
2. THE UNTOUCHABLES - Ocular Surface Squamous neoplasia
(Dr. Soosan Jacob)
3. Excision of Ocular Surface Squamous Neoplasia
(Santosh Honavar)
4. Tumors of The Eyelids - High Yield Ophthalmology Lectures Made Easy
5. basal cell carcinoma and squamous cell carcinoma of eye lid easy explanation
(peshawar medic)
6. AIOC2018 - IC423 - Topic - Ocular surface squamous neoplasia: Diagnosis and management
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