MelanA

Melan‑A (MART‑1) is a melanocyte‑specific cytoplasmic protein involved in the formation of stage II melanosomes and serves as a sensitive melanocytic lineage marker in IHC. It shows cytoplasmic staining and is positive in most primary melanomas (though desmoplastic melanoma may be negative) and is more sensitive than HMB‑45 for detecting metastatic melanoma. Melan‑A also stains non-melanocytic tumours that contain melanosomes such as angiomyolipoma, PEComa, and lymphangioleiomyomatosis. Depending on the antibody clone, it may also stain adrenal cortical and sex‑cord stromal tumours due to cross‑reactivity rather than true Melan‑A expression (1-2).

Recommended Controls

Criteria for acceptable staining is a cytoplasmic staining pattern. Recommended control to include is a known malignant melanoma (positive-high expressor), normal lung (negative control) and/or a section of normal skin (normal dermal melanocytes will stain positive).

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.