Reviewer: Lauren Stuart, M.D., M.B.A. (see Reviewers page)
Revised: 3 November 2015, last major update May 2013
Copyright: (c) 2002-2015,, Inc.
Definition / General
  • Also called T311 (for immunohistochemistry)
  • Melanocyte specific antigen important in melanin synthesis and melanosome formation
  • Interpretation: cytoplasmic staining
Uses by Pathologists
  • Identification of melanocytic neoplasms
Micro Images

Normal skin-prominent melanocytes (a);
melanoma-positive homogenous tumor cells (b)

Melanoma (image 3, cytology)

Renal angiomyolipoma (image 4, weak)

Positive Staining - Normal
Positive Staining - Disease
Negative Staining