Primary benign conjunctival tumors
1. Conjunctival nevi are congenital benign malignant neoplasms originating from neuroectodermal layer and rarely become malignant. Histopathologically, conjunctival nevi are composed of nevus cells or nests. 1/3 of conjunctival nevi lack pigment, and more than half of them have cyst-like epithelial inclusions. Conjunctival nevi are mostly found in the bulbar conjunctiva near the corneal limbus and the lid fissure, and are irregularly round, varying in size, with clear boundaries and slightly elevated on the conjunctival surface. The nevus is usually black, with varying shades of pigmentation, and some are brownish red. There are no blood vessels in the nevus. If the nevus suddenly becomes large and rough on the surface with blood vessels growing into it, it indicates the possibility of malignant transformation. Pigmented conjunctival nevus should be distinguished from primary acquired conjunctival nevus, which is usually unilateral, irregular, flat and diffuse pigmentation with a tendency of malignant transformation.
It usually does not require treatment. If it affects the appearance, it can be excised, but care should be taken to make sure that the excision is complete. Once malignancy is found, extensive and complete excision should be given to avoid recurrence.
2. Conjunctival papilloma (conjunctival papilloma)
Human papillomavirus (HPV) subtypes 6 or 11 can induce proliferation of epidermal cells and blood vessels in the eyelid skin to form common warts or stalked conjunctival papillomas. HPV-16 or HPV-18 often cause conjunctival lesions with a wide base. Pathology shows papillomas with a connective tissue core covered with proliferating epithelium, moderate epithelial keratinization, and occasional irregular growth.
They often occur at the corneal limbus, lacrimal caruncle, and lid margin, and are bright red and flesh-like in appearance. Lobulated conjunctival papillomas consist of multiple lobules and have a smooth, spiral vascular appearance. Wide basal papillomas have an irregular surface and sometimes spread to the cornea. Biopsy is helpful for diagnosis. Papilloma is prone to recurrence after surgical excision, and local injection of bleomycin can reduce the recurrence rate.
3. Conjunctival dermoid tumor (dermoid tumor) and dermoid lipoma (dermolipoma)
They are common congenital benign tumors. Dermoid tumors are commonly found at the inferior temporal cornea margin and appear as round, smooth, yellow, raised masses, in which hair is commonly present. Dermatofibroma is most often seen in the superior temporal quadrant near the outer canthus under the bulbar conjunctiva as a yellow, soft, smooth mass. It usually does not require treatment, but if its growth expands and affects the aesthetics, partial excision can be considered. Caution should be exercised for posterior excision because it is connected with orbital fat and surgery may cause complications such as orbital disorders, which are more serious than the original disease.
4.Conjunctival angioma
Most of them are congenital and appear at birth or shortly after birth. Conjunctival angiomas can appear as isolated, masses, or diffusely dilated spongiform angiomas. It is usually associated extensively with eyelid skin and orbital capillary hemangiomas, as well as venous hemangiomas, and should be distinguished from dilated conjunctival capillaries, as in Rendu-Osler-weber disease or Louis-Bar syndrome.
Septic granulomas and capillary hemangiomas often coexist on the conjunctival surface of lid cysts or in areas where surgery has recently been performed. AIDS-associated Kaposi’s sarcoma, which presents as a blue vascular nodule on the conjunctiva, is most effectively treated with radiation therapy.
5. Conjunctival inclusion cyst (Cyst)
Small conjunctival cysts may be due to ectopic conjunctival folds. Larger cysts are often caused by abnormal proliferation of conjunctival epithelial cells that have implanted into the subepithelial stroma of the conjunctiva as a result of trauma, surgery, or inflammation. Conjunctival cysts are well-defined and surrounded by normal conjunctival epithelial cells, and are most often located in the inferior lid vault. Recurrence rate is high with incision and drainage of the cyst alone, complete surgical excision is an effective treatment, and amniotic membrane transplantation is feasible when the extent of the defective area after excision is large.
II. Primary conjunctival malignancy
1. Conjunctival epithelial neoplasia (CIN)
CIN is similar to actinic keratosis of the eyelid skin and is classified as mild, moderate, or severe according to the extent to which atypical cells invade the epithelium; if the lesion is limited to part of the epithelium, it is called squamous cell dysplasia; when atypical cells develop throughout the epithelium, it is carcinoma in situ. The causative factors are related to excessive sunlight exposure, human papillomavirus infection, etc. The incidence is higher in outdoor working population, smoking elderly male population, and the development of lesions is faster in immunosuppressed patients such as AIDS.
Conjunctival intraepithelial neoplasia mostly grows in the exposed area of the lid fissure, near the corneal limbus. They can have a papillary or gelatinous appearance, grow slowly, and are often associated with mild inflammation and varying degrees of vascular abnormalities. If the neovascularization into the focal area is coarse, it means that the conjunctival epithelium has a tendency to grow infiltratively at noon and may break through the basement membrane.
Surgical excision is an effective treatment, but there is a possibility of recurrence, and a recurrence rate of approximately 30% has been reported to still exist in patients with a negative pathological examination of the excision margin after surgical excision. Therefore, some scholars suggest that after resection of the lesion, the tissue adjacent to the resection margin should be cryotherapy or anti-metabolic drugs such as mitomycin and 5-FU should be used to reduce the recurrence of the tumor.
2.Conjunctival squamous cell carcinoma
It is a relatively common malignant tumor of the conjunctiva. Excessive exposure to ultraviolet light is an important factor in the development of squamous cell carcinoma, and viral infection and congenital factors may also play a role. Squamous cell carcinoma occurs more frequently in HIV-positive patients and in patients with hyperpigmented dry skin disease.
They occur mostly at the corneal margin in the lid fissure area, at the junction of the skin of the lid margin and the conjunctiva, or at the inner canthus in the lacrimal caruncle, and are rarely seen in the non-exposed areas of the conjunctiva. Some tumors resemble pterygium in appearance. Most tumors are gelatinous with abnormal epithelial keratinization. The tumors grow slowly but can infiltrate deeper tissues and rarely metastasize.
Therefore, complete excision of the lesion is the best treatment, with trauma repaired with mucosal, conjunctival, or amniotic membrane grafts and corneal trauma with lamellar corneal grafts. Incomplete resection of the tumor can recur, and a second surgery is required at that time. Cryopreservation can reduce the recurrence rate. Subconjunctival injection of bleomycin into the focal area of the cancer has been reported to shrink the cancer. If the lesion has invaded the eyelid or the dome and cannot be completely removed, orbital content enucleation should be considered.
3.Malignant melanoma
Conjunctival malignant melanoma is a potentially fatal tumor. Metastases to important organs have been reported to occur in 26% of patients at an advanced stage, with a mortality rate of 13% in patients 10 years after surgery. Most malignant melanomas arise from acquired primary melanomas, some from conjunctival pigmented nevi, and very rarely from normal conjunctiva.
Conjunctival melanoma is most commonly found in the bulbar conjunctiva or keratoscleral rim, but can also appear in the lid conjunctiva as a nodular growth with abundant trophoblastic vessels and variable shades of pigmentation. The prognosis depends to some extent on the site of the lesion, with melanomas growing in the bulbar conjunctiva having a better prognosis than those occurring in the lid conjunctiva, fornix, or tear trough. Melanoma can invade the eye or orbit and can metastasize to local lymph nodes, brain, and other sites.
Excisional biopsy should be performed on any suspicious pigmented lesion on the ocular surface; proper biopsy does not increase the risk of metastasis. Most conjunctival melanomas are surgically resectable. The recommended approach is to excise the conjunctiva up to 4 mm beyond the tumor border and a thin lamellar scleral flap beneath the tumor, with the sclera in the surgical area treated with anhydrous alcohol and the conjunctival wound margin cryotherapy. Conjunctival or amniotic membrane grafting can be performed for larger conjunctival resection areas to prevent postoperative adhesions. For progressive lesions, where local excision is not possible, ophthalmic removal or enucleation of orbital contents may be considered. Radiotherapy does not necessarily improve surgical healing.