KBA62

The antibody KBA62 was raised against the KAL melanoma cell line and recognises an unknown antigen expressed by melanomas1. By immunoblotting analysis KBA.62 reacts with 140, 135, 128, 88, and 73 kD polypeptide chains, which are different from those reported for HMB451:

Immunohistochemical expression

Positivity is seen in :

Staining of melanomas is predominantly of the cell membrane (cf. cytoplasmic staining with HMB45)1.
Subepithelial stromal cells of the urinary bladder6.
smooth muscle (vascular and visceral in gastrointestinal tract, gallbladder and prostate) and pericytes (unlike other melanoma markers)6.
Occasional endothelial cells are positive1.
Skin hair follicles stain1.
Basal cells of epidermis, tonsils and uterine ectocervix6.
Mesangium of renal glomerulae6.
Astrocytes6.
Variable in bronchial chondrocytes6.

There is negativity in:

Basal melanocytes in normal skin1.

				KBA62
	Naevi		junctional	1/11,
			intradermal	7/71,
			compound	8/81,
			Spitz	2/2(cf. S100: 2/2)1,
			dysplastic	3/3(cf. S100: 3/3)1,
			total	21/211, 93%(of 70 cases)5, 27/27(Prominent cytoplasmic positivity)6,
	Melanomas	primary	superficial spreading	27/291,
			nodular	6/71,
			desmoplastic	9/124, 53%(of 19 cases)5, 28/346,
			sacral lentiginous	1/11,
			lentigo	2/21,
			GI mucosal	39/546,
		metastatic		39/471, 184/2146
		total		75/86 (87%)1, 65%(of 92 cases)5,
	Clear cell sarcoma			15/166,

	Carcinomas	skin	squamous cell carcinoma	5/61,
			basal cell carcinoma	2/41,
			Merkel cell	0/46,
		larynx	squamous cell	26/316,
		lung	squamous cell carcinoma	2/71, 25/546,
			adenocarcinoma	0/101, 4/326,
			small cell carcinoma	0/61,
			large cell carcinoma	5/456,
			oesophagus, squamous cell	17/276,
		gastrointestinal	stomach	1/91, 2/486,
			small intestine	0/41,
			large intestine	0/91, 0/486,
		liver	cholangiocarcinoma	4/206,
			hepatocellular	0/396,
		breast		1/81, 9/71(9/66 ductal, 0/5 lobular)6,
		thyroid		0/111, 3/53(2/4 follicular, 1/49 papillary)6,
		pancreas		0/11, 5/276,
		ovary		0/21, 3/34(mostly serous)6,
		kidney		0/41,
		bladder, transitional cell		3/256,
		prostate		0/21, 0/506,
		testis, embryonal carcinoma		2/226,
		endometrium, adenocarcinoma		2/206,
		cervix, squamous cell		14/226,
		adrenocortical		0/21,
		nasopharynx		0/21,
		thymus		0/11,
		sarcomatoid carcinoma larynx/intestine		18/396,
		unknown origin		0/31,
	Haematolymphoid	chronic myeloid leukaemia		1/66,
		blastic extramedullary myeloid tumour		1/116,
		non Hodgkin lymphoma		0/281,
		small B-cell lymphoma		0/136,
		diffuse large B-cell lymphoma		0/206,
		Hodgkin lymphoma		0/191,
	Others	nerve tumours		0/71, 19%5,
		neurofibroma		42/426,
		Schwannoma		13/176,
		malignant peripheral nerve sheath tumour		4/84, 16/216,
		vascular tumours		0/91,
		mammary adenofibroma		0/11,
		carcinoid		0/61,
		phaeochromocytoma		0/21,
		nephroblastoma		0/31,
		renal oncocytoma		0/11,
		testis, seminoma		12/436,
		mesothelioma		0/11, 5/31(delicate membrane staining)6,
thymoma		0/21,
leiomyoma		0/41,
histiocytofibroma		0/11,
liposarcoma		0/11,
synovial sarcoma		0/11, 9/146,
leiomyosarcoma		32/336,
leiomyoblastosarcoma		0/11,
rhabdomyosarcoma		0/31,
Ewing sarcoma		0/11,
		scar tissue		1/44,
		nodular fasciitis		15/156,
		PEComa, liver and uterus		1/136,
		lymphangioleiomyomatosis		3/76,
		angiomyolipoma of kidney		0/176,
		angiosarcoma		4/146,
		GIST, stomach and intestine		73/1036,
		solitary fibrous tumour / haemangiopericytoma		10/366,
		malignant fibrous histiocytoma		11/326,
	meningioma		4/166,

Diagnostic utility

Another marker for melanoma. It may be helpful along with S100 in the identification of desmoplastic melanoma but does not help in the differentiation from nerve sheath tumours.

References

1 Cohen-Knafo E, al Saati T, Aziza J, Ralfkiaer E, Selves J, Gorguet B, et al. Production and characterisation of an antimelanoma monoclonal antibody KBA.62 using a new melanoma cell line reactive on paraffin wax embedded sections. J Clin Pathol. 1995 Sep;48(9):826-31.

2 Kaufmann O, Koch S, Burghardt J, Audring H, Dietel M. Tyrosinase, melan-A, and KBA62 as markers for the immunohistochemical identification of metastatic amelanotic melanomas on paraffin sections. Mod Pathol. 1998 Aug;11(8):740-6.

3 Pages C, Rochaix P, al Saati T, Valmary-Degano S, Boulinguez S, Launay F, et al. KBA.62: a useful marker for primary and metastatic melanomas. Hum Pathol. 2008 Aug;39(8):1136-42.

4 Bernaba BN, Vogiatzis PI, Binder SW, Cassarino DS. Potentially useful markers for desmoplastic melanoma: an analysis of KBA.62, p-AKT, and ezrin. Am J Dermatopathol. 2011 Jun;33(4):333-7; quiz 8-40.

5 Shanesmith RP, Smart C, Cassarino DS. Tissue microarray analysis of ezrin, KBA.62, CD166, nestin, and p-Akt in melanoma versus banal and atypical nevi, and nonmelanocytic lesions. Am J Dermatopathol. 2011 Oct;33(7):663-8.

6 Aung PP, Sarlomo-Rikala M, Lasota J, Lai JP, Wang ZF, Miettinen M. KBA62 and PNL2: 2 new melanoma markers-immunohistochemical analysis of 1563 tumors including metastatic, desmoplastic, and mucosal melanomas and their mimics. Am J Surg Pathol. 2012 Feb;36(2):265-72.

This page last revised 29.2.2012.