Study Shows Long-Term Outcomes of Conjunctival Melanoma

Researchers at the Wills Eye Hospital in Philadelphia examined the long-term outcomes of conjunctiva melanoma and found the 10-year risk per tumor category significantly increased for visual acuity loss of more than 3 lines, tumor recurrence, new tumors, exenteration, locoregional and systemic melanoma-related metastasis, and melanoma-related death. The findings were published in the Asia-Pacific Journal of Ophthalmology.

Conjunctival melanoma, a rare malignancy thought to be increasing in frequency in recent years, is classified according to the AJCC into clinical and pathologic T categories and T subcategories. As the AJCC updated to the 8th edition in 2017, a team of investigators conducted a retrospective interventional case series analysis to evaluate the outcomes of conjunctiva melanoma based on recent clinical classifications. 

A total of 425 patients (mean age 62.7 years; 51% men, 49% women) with conjunctival melanoma were included in the study; 63%, 18%, and 20%, were classified as T1, T2, and T3. No patients were in the T4 category. Of the cohort, 83% had a history of primary acquired melanosis (PAM), 16% had a history of conjunctival nevus, 5% had a history of melanocytosis, and 4% had a history of complexion-associated melanosis. 

A history of PAM was more common in T2 than in T1 or T3 (P =.01), while a history of conjunctival nevus was most common in T1 (P =.03). An increase in T category was associated with a more common history of previous conjunctional surgery (P =.02), a higher mean number of conjunctival surgeries (P =.03), and a greater likelihood of previous eyelid surgery (P <.001). 

Similarly, among patients with follow-up (n=381; mean follow-up, 57.6 months), an increase in T category was also associated with an increase in local recurrence/new tumor (P =.004), increased exenteration (P <.001), increased melanoma-linked locoregional lymph node metastasis (P =.001), increased melanoma-linked systemic metastasis (P <.001), and increased melanoma-linked death (P <.001). 

A comparison of the 3 T categories at 10 years also suggested a link between increasing T category and a higher probability of visual acuity loss of 3 or more lines, melanoma recurrence/new tumor, exenteration, melanoma-related locoregional lymph node metastasis, melanoma-related systemic metastasis, and melanoma-related death (all P <.001). 

“We have experienced no cases of T4 conjunctival melanoma in this series regarding the AJCC 8th edition and in our previous series on the AJCC 7th edition,” according to the report. “Perhaps given the low frequency of T4 (tumor of any size with central nervous system involvement), the classification should be reconsidered and T4 could be merged with T3 as the most advanced subcategory (T3e) rather than having an entirely new category for a nearly absent subset of tumors.”

Reference 

Shields CL, Yaghy A, Dalvin LA, et al. Conjunctival melanoma: outcomes based on the American Joint Committee on Cancer Clinical Classification (8th edition) of 425 patients at a single ocular oncology center. Asia Pac J Ophthalmol. 2020;10(2):146-151. doi:10.1097/APO.0000000000000343