PRAME

PRAME (Preferentially Expressed Antigen in Melanoma) is a cancer‑testis antigen that shows diffuse nuclear immunoreactivity in most melanomas, including in situ, invasive, and metastatic lesions, while benign nevi typically display absent, focal, or non-diffuse staining. Its expression is largely restricted in normal tissues aside from testis, making it a valuable IHC marker for distinguishing malignant melanocytic tumours from benign lesions. PRAME can also be variably expressed in some non-melanocytic malignancies, but its consistent diffuse nuclear staining pattern in melanoma reveals its diagnostic advantage in dermatopathology(1).

Recommended Controls

The criteria for acceptable staining is nuclear. A malignant melanoma should demonstrate positive staining in the tumour cells and normal skin should stain the sebaceous glands only. The recommended controls to use is testis (as the low expressor) and a high expressor, melanoma.

Expected staining pattern

Malignant melanoma

Normal skin

Disclaimer

These methods are intended as a guide only. Laboratories that wish to implement these methods should perform internal validation/verification prior to use. The RCPAQAP does not make any claim or warranty for the accuracy or performance of these methods.