Ocular Squamous Cell Carcinoma

What is Squamous Cell Carcinoma?

Conjunctival Squamous Cell Carcinoma is 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. Some believe that excessive exposure to sunlight from outdoor activities like sunbathing, golfing, fishing, and other sports can lead to this tumour. Large dilated red blood vessels leading to the tumour on the eye might also be visible. 

Squamous cell carcinoma is locally invasive so it could invade and destroy the eye. This cancer rarely spreads to distant sites and most people are cured of this cancer with appropriate treatment. The recommended management depends on the size and extent of cancer. Sometimes it is surgically removed by complete excision in the operating room. Occasionally a tissue graft (amniotic membrane transplant) is necessary to cover the hole where the tumour was removed. Sometimes this cancer can be treated with special chemotherapy eye drops that are used for a few weeks or up to one year. Sometimes an injection of chemotherapy cures cancer. An experienced doctor should make the decision regarding the method of treatment

What are the symptoms?

• Bleeding
• Pruritis, irritation
• Pain
• Anaesthesia
• Enlarging lesion
• Crusting lesion

What are the risk factors?

• Ultraviolet light exposure (CSCC): cumulative toxicity from unprotected sunlight, indoor tanning salons
• Ionizing radiation
• Arsenic exposure
• Chronic irritation
• Human papillomavirus (MSCC)
• Immunocompromised status
• Actinic keratosis (AK)
• Squamous intraepithelial neoplasia (Bowen's disease)

How is it diagnosed?

Diagnosis is usually made based on clinical suspicion based on the appearance of the lesion especially in patients with high-risk factors. The diagnosis is confirmed by obtaining a biopsy and examining the histopathology.

History

Suspicious skin lesion, especially in high-risk patients

Previous skin lesions, histopathology, procedures, etc

Physical examination

Complete ophthalmic examination, including ocular motility and assessment of proptosis

Assessment of facial sensation

Palpation of regional lymph nodes: preauricular, submandibular and cervical

Examination of the lesion includes assessment for:

• The general appearance of the lesion and periocular skin
• Distortion of eyelid architecture or eyelid malposition
• Presence of skin ulceration
• Madarosis (loss of eyelashes)
• Telangiectasias

Differential diagnosis

The differential diagnosis includes any benign or malignant condition of the eyelid skin, including:

Benign

• Seborrheic keratosis
• Actinic keratosis
• Keratoacanthoma
• Chalazion
• Cyst
• Squamous papilloma
• Blepharitis
• Xanthelasma
• Nevus
• Verruca

 

Malignant

• Basal cell carcinoma
• Sebaceous gland carcinoma
• Malignant melanoma
• Lymphoma
• Merkel cell tumour
• Metastasis

What is the treatment?

Surgery is the principal method of treatment after ruling out regional spread which may be as high as 20-30%. Small, well-differentiated lesions may be treated with cryotherapy or photodynamic therapy. Superficial extensive lesions may also be treated with Imiquimod.

Determination of tumour margins during surgical excision may be more difficult with SCC than with BCC, as SCC tends to have more ill-defined margins. SCC is associated with a risk of regional lymph node metastasis. For periocular SCC, the risk of regional lymph node metastasis may be as high as 20-30%, according to series from tertiary cancer centres. Sentinel lymph node biopsy may be considered in high-risk patients, such as recurrent lesions or those with SCC greater than 2 cm in diameter or perineural invasion. SCC is also associated with a risk of metastasis to distant organs, which increases with these high-risk features.

Surgery

Complete surgical excision with margin control is the ideal modality of management. However, determining tumour margins clinically may be challenging compared to Basal Cell Carcinoma, as the edges may be less well defined. Patients with large and extensive lesions especially with perineurial invasion and recurrent lesions may benefit from Sentinel Lymph node biopsy with radical dissection as indicated, after ruling out distant metastasis.

Other treatment options

Photodynamic therapy is emerging as a promising treatment for patients with multiple or large SCC in whom surgery is not appropriate. In such cases, PDT is associated with reasonable efficacy, good cosmesis and limited morbidity. However, the precise role of PDT remains uncertain at this time.

Small and superficial lesions may also be treated with cryotherapy or Imiquimod applications

Recent advances have been made with the advent of Checkpoint inhibitors for extensive and inoperative squamous cell carcinoma and metastatic carcinoma. PD-1 inhibitors (Cemiplimab) has been recently FDA approved for this indication.

What are the complications?

Misdiagnosis, lack of histologic control, Incomplete excision, local tumour recurrence, regional spread metastasis are not uncommon with medical and medicolegal implications.

Prognosis

With early, adequate treatment the prognosis is excellent. However, a mortality rate of close to 15% has been reported. Poor prognostic factors include:

• Poorly differentiated tumours
• Perineural spread
• Orbital invasion
• Immunosuppression

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