Track: Basic Science

Topic: Melanocytic Neoplasms

Abstract:

Expression of AMBRA1 and loricrin in the epidermis overlying primary melanomas has recently been validated as a prognostic biomarker able to identify genuinely low risk non-ulcerated AJCC Stage I/II tumours¹. The objective of the present study was to evaluate the potential for these biomarkers to characterise a range of cutaneous melanocytic lesions other than conventional melanoma. Sections were obtained from 40 benign/dysplastic naevi, 146 melanoma in situ and 315 Spitzoid lesions from the archives of Cambridge and Newcastle Hospitals. Automated immunohistochemical analysis for AMBRA1 and loricrin was undertaken. Staining patterns were evaluated using consensus scoring by the study pathologists (AH, PS, NS). All benign and dysplastic melanocytic naevi showed maintenance of both AMBRA1 and loricrin in the epidermis overlying the lesion. Maintained epidermal AMBRA1/loricrin was also observed in most melanoma in situ cases, but 6 displayed focal losses. Spitzoid lesions showed variable expression including a distinctive chequerboard pattern of AMBRA1 staining and alternating thin and multilayered loricrin expression. The maintained pattern of AMBRA1 and loricrin in melanocytic naevi is consistent with their benign nature. However, loss of expression of AMBRA1/loricrin in 6 cases of melanoma in situ was unexpected, suggesting that some cases may have the potential to progress. Further ongoing analysis of epidermal AMBRA1/loricrin in a larger cohort of Spitzoid lesions is currently underway in order to determine whether these biomarkers can distinguish between benign lesions and those at risk of malignant progression.

¹Ewen et al 2024, British Journal of Dermatology, 190: 549-558M

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Marie Labus, BSc, PhD