Purpose: In primary conjunctival melanoma (CoM), one of the characteristics that is associated with an increased risk of metastases and death is a lack of tumour pigmentation. The aim of this study was to investigate whether the degree of pigmentation of CoM recurrences relates similarly to clinical outcome.
Methods: A data set of 177 patients with a CoM recurrence from the Wills Eye Hospital (USA) and the Leiden University Medical Center (The Netherlands) was analysed. The relation between clinical tumour pigmentation of the recurrences, the characteristics of the primary lesions and clinical outcome was investigated.
Results: In 117 (66%) of 177 patients with a CoM recurrence, tumour pigmentation was known: 71 patients (61%) had recurrences with low pigmentation. Primary lesions had low pigmentation in 39% of cases, which is significantly different (p = 0.001). However, low tumour pigmentation of recurrences correlated with low tumour pigmentation of the primary lesion (p < 0.001). No association was observed between pigmentation of the recurrences and iris colour (p = 0.66). Low pigmentation of the recurrences was not significantly associated with an increased risk for metastases (HR 1.96, p = 0.12) or death (HR 1.79, p = 0.27), whereas primary tumours with low pigmentation did show a greater risk for metastases (HR 2.82, p = 0.016) and death (HR 2.90, p = 0.037).
Conclusions: CoM recurrences are more often lightly pigmented compared to primary lesions. A correlation exists between the degree of pigmentation of primary and recurrent lesions, but recurrences can appear with any degree of pigmentation. Unlike primary CoM, the level of pigmentation of CoM recurrences is not related to metastasis or death.
Keywords: Conjunctival melanoma; Melanin; Oncology; Pigmentation; Recurrences.