Comparative expression of cyclooxygenase 2 and Ki67 in amelanotic and conventional oral melanomas

Abstract

Background Oral melanomas have some histopathological resemblance with its cutaneous counterpart; however, an aggressive behavior is more common in tumors that occur in the oral cavity. Several markers have been suggested as indicative of tumoral progression and aggressiveness, such as cyclooxygenase 2 (COX-2) and Ki67. Material and Methods In this study, we have compared the expression of COX-2 and Ki67 in a series of amelanotic (n=7) and melanotic oral melanomas (n=22). The cases were selected from 4 pathology laboratories and submitted to the immunohistochemical (IHC) reactions. We analyzed the IHC staining based on a qualitative – using visual scores; and a computer-assisted method (quantitative) using scanned slides and software for digital analysis. Results COX-2 was expressed in all oral melanomas; however, its intensity was significantly higher in the amelanotic ones ( P <0.001). Similarly, a high Ki67-positivity index was observed in the amelanotic than melanotic ones ( P <0.001). Conclusions Based on these results, we suggest that amelanotic oral melanomas have marked pro-inflammatory and high-proliferative phenotype, justifying their more aggressive behavior compared with the melanotic ones. Key words: Oral melanoma, amelanotic tumor, cyclooxygenase 2, Ki67.

Cyclooxygenase-2 (COX-2) Expression in Equine Melanocytic Tumors

“…Although pigmentation is not fully considered a clinical/histological marker of aggressiveness, it has been reported in most species that amelanotic melanocytic tumors are often more aggressive. In 2020, Soares et al also reported that amelanotic melanomas presented a significantly higher COX-2 intensity of labelling than did conventional melanomas [ 69 ]. Such a conclusion could not be drawn in our work due to the limited number of amelanotic melanomas and the absence of clinical history.…”

Clinicopathological and prognostic value of Ki-67 expression in oral malignant melanoma: A systematic review and meta-analysis

“… 23 The amelanotic nature of the lesion in the oral type has not been well examined. Soares et al 24 reported that elevated Ki-67 levels in non-pigmented melanomas also suggested a more aggressive condition.…”