Melan A or Mart-1, like HMB 45 is an antibody marker that reacts with antigens present in conditions like melanoma. This as well as being useful for identification of melanomas, also has the useful function of being able to identify tumour cells in lymph nodes. Melan A due to its staining up colouration of normal melanin is more useful in IHC staining if the staining used is red staining based on Alkaline phosphatase rather than the usual staining with DAB or diaminobenzidine tetrahydrochloride.

The staining pattern of Melan A is Cytoplasmic as shown below.

Picture 1 – Red staining of Melan A positivity in Malignant melanoma in skin

 

The staining pattern of Melan A is much easier to see in the red staining above to distinguish it from the normal melanin rather than using DAB as shown below.

Picture 2 – DAB staining of Melan A positivity in skin

 

Melan A has several different applications. Below are a few examples.

Tumour or cell type	Melan A + or -
Adrenal Carcinoma	Positive
Primary clear cell sugar tumour	Positive
Malignant melanoma	Positive
Dermatofibroma	Negative