Across the academic literature, mounting evidence shows that cases of conjunctival melanoma in the United States are increasing. Researchers speculate this is connected to increasing sunlight exposure. A recently published study proposes another host risk factor; skin type. Research published in the journal Ophthalmic Plastic & Reconstructive Surgery asks if an individual’s degree of cutaneous pigmentation impacts their risk of developing melanoma. Using the Fitzpatrick skin type (FST) scale, investigators  found that most participants with conjunctival melanoma have more fair skin. However, where they fell on the FST scale did not impact their 5-year rates of visual acuity loss greater than or equal to 3 lines, tumor recurrence, enucleation, exenteration, metastasis or death. 

The investigators specifically identified that 85% of conjunctival melanoma patients qualify as FST Types I and II. Other factors associated with conjunctival melanoma in the study include  older mean age, greater female preponderance, less often complexion associated melanosis, smaller tumor thickness, and less eyelid involvement. FST Types I and II also experienced poorer final visual acuity and a greater percentage of visual acuity loss greater than or eequal to3 lines, as well as a greater number of recurrences.

The researchers reviewed 540 medical records of patients with pathologic diagnosis of conjunctival melanoma managed by the Ocular Oncology Service at Wills Eye Hospital, Philadelphia, between April 18, 1974 and September 9, 2019. The subjects were classified according to the FST based on external facial photography at initial presentation. This classification breakdown is as follows, with increasing suntan and decreasing sunburn potential:


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• Type I (white skin color) 126 (23%) participants 

• Type II (fair skin color) 337 (62%) participants

• Type III (average skin color) 56 (10%) participants 

• Type IV (light-brown skin color) 8 (2%) participants 

• Type V (brown skin color) 12 (2%) participants 

• Type VI (black skin color) 1 (<1%) participant

For analysis purposes, Types III, IV, V and VI were combined, representing 14% of the total participants. 

Comparing FST I vs II vs III, IV, V, and VI revealed FST Types I and II associated with older mean patient age (63.9 years vs 60.7 years vs 51.1 years, P <.001), greater percentage of female patients (68% vs 44% vs 42%, P <.001), lower frequency of complexion associated melanosis (1% vs 2% vs.13%, P <.001), smaller tumor thickness (2.1 mm vs 2.8 mm vs 3.6 mm, P =.01), and less eyelid involvement (13% vs 13% vs 28%, P =.02).

Demographic data included age, race, sex, involved eye as well as smoking history. Clinical features at presentation included best-corrected visual acuity, largest tumor basal diameter, tumor thickness, number of quadrants involved (1 to 4), number of clock hours involved (0 to 12), tissues involved (bulbar conjunctiva, limbus, cornea, plica, caruncle, fornix, tarsal conjunctiva, eyelid, and orbit), American Joint Committee on Cancer classification (8th edition), presence of feeder and intrinsic vessels, and tumor pigmentation (absent, partial, and complete).

To evaluate outcomes, the researchers reviewed visual acuity loss of at least 3 lines, local tumor recurrence after referral to Ocular Oncology Service at Wills Eye Hospital, need for enucleation or exenteration, metastasis, site of metastasis (locoregional lymph nodes and systemic), and death. 

The retrospective design, judgement of FST based on facial skin color, and the fact that some cases had surgery prior to referral could all be considered limitations for this study. Additionally, FST classification was made based on facial photographs, not the typical method that bases it on skin color of the inner arm or buttock.

The authors suggest that patients with FST Types I and II could be considered a phenotype at risk for conjunctival melanoma and monitored accordingly.

Reference


Shields C, Yaghy A, Dalvin L, et al.. Conjunctival melanoma: features and outcomes based on the Fitzpatrick Skin Type in 540 patients at a single ocular oncology center. Ophthalmic Plast Reconstr Surg. Sep/Oct 2020;36(5):490-496. doi: 10.1097/IOP.0000000000001624.