The expression of human high molecular weight melanoma-associated antigen in acral lentiginous melanoma.

The high molecular weight melanoma-associated antigen (HMW-MAA) is a membrane-bound chondroitin sulphate proteoglycan that is highly expressed on the surface of melanoma cells. It represents an attractive target for immunotherapy of malignant melanoma. Previously, it was reported that HMW-MAA was detected in about 20-30% of primary acral lentiginous melanoma (ALM) lesions by immunohistochemical staining (IHC) of frozen sections with monoclonal antibodies (mAbs). In the present study, we examined the expression of HMW-MAA in 95 paraffin-embedded, primary ALM lesions and 13 primary superficial spreading melanoma (SSM) lesions. A total of 51 primary ALM lesions (53.6%) were positive for HMW-MAA. Almost all of these positive cases showed a weak staining intensity. On the other hand, all 13 primary SSM lesions were strongly positive for HMW-MAA expression. Our data showed that the staining intensity of HMW-MAA ALM lesions was weaker than that of SSM. Furthermore, the percentage of HMW-MAA positive staining in ALM lesions was higher than previously reported.