Melan-A:  a melanocytic differentiation marker

The Melan-A gene, also known as MART-1 (Melanoma Antigen Recognised by T-cells), was cloned from a melanoma cell line.  Its subcellular location is not yet certain, but it is thought to be associated with melanosomes and endoplasmic reticulum.  The gene is expressed in melanocytes of the skin and retina, malignant melanoma.  The only cells, other than melanocytes, which express the gene are found in angiomyolipomas.

Two monoclonal antibodies have been raised;  A103 and M2-7C10.  Both are available commercially.  Both are suitable for use on paraffin-embedded, formalin-fixed tissue.  A103 has been the most extensively studied in histological material; MC-7C10 has been studied mainly in cytological preparations.


Immunohistochemical expression

A103 shows immunoreactivity with:


Diagnostic utility



Advances in Anatomic Pathology 1999; 6:12-18

Stewart CJR et al. Value of A103 (melan-A) immunostaining in the differential diagnosis of ovarian sex cord stromal tumours. J Clin Pathol 2000; 53: 206-211.

3Miettinen M et al. Microphthalmia transcription factor in the immunohistochemical diagnosis of metastatic melanoma: comparison with four other melanoma markers. Am J Surg Pathol 2001;25:205-211.


©SMUHT/PW Bishop