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MelanA / MART1

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 30 December 2012, last major update December 2012
Copyright: (c) 2002-2012, PathologyOutlines.com, Inc.
PubMed Search: Melan-A [title]
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● Commonly used melanocytic markers; MelanA also called A103; are separate antibodies that occasionally have different staining properties
Melanocytic Antigen Recognized by cytotoxic T lymphocytes from melanoma patients
● Cytoplasmic protein sensitive and specific for melanoma and melanocytic lesions

Uses by pathologists

● Recommended for evaluating sentinel lymph nodes for melanoma (Am J Surg Pathol 2001;25:1039), although also stains benign nevi (Am J Surg Pathol 2002;26:1351) and normal melanocytes
● Differentiate adrenal cortical tumors (MART1+) vs. renal cell carcinoma or pheochromocytoma (MART1-)
● Differentiate neurotized melanocytic nevi (MelanA+) from neurofibroma (MelanA-, Arch Pathol Lab Med 2012;136:810)
● Distinguish in situ and invasive melanoma, and measure thickness (Am J Dermatopathol 2012 Jun 8 [Epub ahead of print])
● Caution: may overestimate presence of lentigo maligna (Dermatol Surg 2011;37:657, J Cutan Pathol 2011;38:775)

Micro images

Adrenal gland: normal plus quality control and other images

Adrenal gland: adrenocortical adenoma (left) is MelanA+; pheochromocytoma (right) is MelanA-

Bladder: PEComa

Eye: conjunctival melanoma

Kidney: atypical epithelioid angiomyolipoma

Pancreas: PEComa (MelanA+)

Skin: basomelanocytic tumor (note staining of melanocytic component on left but not of basal cell carcinoma component on right)

Skin: benign fibrous histiocytoma, epithelioid variant (MelanA-)

Skin: dermal nevus with associated fibrohistiocytic proliferation (fig b)

Skin: desmoplastic blue nevus

Skin: melanoma - lentiginous (figures a / b)

Skin: melanoma - sentinel lymph nodes with "stealth" metastases (Am J Surg Pathol 2011;35:1657)

Skin: melanoma - superficial spreading (using image analysis to differentiate from nevi, Arch Pathol Lab Med 2012;136:627)

Skin: melanoma - with fibrohistiocytic proliferation (fig b)

Skin: neurotized melanocytic nevi (MelanA+) versus neurofibroma (MelanA-)

Small bowel: metastatic melanoma

Stomach metastatic melanoma (MelanA)

Testis: Leydig cell tumor

Uterus: melanoma

Positive staining - normal

● Melanocytes; steroid-producing cells in adrenal cortex, ovary, testis

Positive staining - disease

● Adrenal cortical adenoma and carcinoma
● Angiomyolipoma
● Clear cell sarcoma of soft parts (43%)
● Nevi
● Lymphangiomyomas
● Melanomas: primary and metastatic, epithelioid, sinonasal
● Paraganglioma-like dermal melanocytic tumor
● Perivascular epihelioid cell tumors (PEComa), includes angiomyolipoma, clear cell "sugar" tumor, lymphangioleiomyomatosis, PEComas from other sites
● Sex-cord stromal tumors

Negative staining

● Carcinoma, mesothelioma (Appl Immunohistochem Mol Morphol 2012 Jul 19 [Epub ahead of print]), Paget's disease, pheochromocytoma
● Atypical fibroxanthoma and undifferentiated pleomorphic sarcoma (rarely positive, J Cutan Pathol 2011;38:954)

End of Stains > MelanA / MART1

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