Desmoplastic melanoma

Desmoplastic melanomas pose particular diagnostic difficulties, since they commonly lack immunoreactivity for the markers used to identify non-desmoplastic melanomas. Apart from S-100, MAGE-1 may be the only marker useful in desmoplastic melanoma⁴. Desmoplastic melanoma appears to be close in immunophenotype to peripheral nerve sheath tumours and they share mutations of the NF1 gene.

Immunohistochemistry

		S-100	Tyrosinase	Mitf	Melan-A	MAGE-1	PNL2	HMB-45
negative		0/201, 0/84, 1/21 (described as "spindle cell and desmoplastic")5	9/201, 30/302, 0/23, 8/84	13/201, 30/302, 8/84, 15/21 (described as "spindle cell and desmoplastic")5	30/302, 8/84, 11/13 (described as "spindle cell and desmoplastic")5	5/84	12/136	14/201, 30/302, 8/84, 17/21 (described as "spindle cell and desmoplastic")5
p o s i t i v e	<5% of cells	0/201	5/201	4/201				5/201
	5-25% of cells	1/201	3/201	2/201				1/201
	25-50% of cells	2/201	2/201	1/201			1/136	0/201
	50-75% of cells	5/201	1/201	0/201				0/201
	>75% of cells	12/201	0/201	0/201				0/201
	any degree of positivity	20/201, 30/302, 8/84, 20/21 (described as "spindle cell and desmoplastic")5	11/201	7/201, 6/21 (described as "spindle cell and desmoplastic", one positive case was negative for both S-100 and HMB-45)5	2/13 (described as "spindle cell and desmoplastic")5	3/84	1/136	6/201, 4/21 (described as "spindle cell and desmoplastic")5

References

¹KJ Busam et al. Analysis of microphthalmia transcription factor expression in normal tissues and tumors, and comparison of its expression with S-100 protein, gp100 and tyrosinase in desmoplastic malignant melanoma. Am J Surg Pathol 2001;25:197-204.

²Miettinen 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.

³Clarkson KS et al. The usefulness of tyrosinase in the immunohistochemical assessment of melanocytic lesions: a comparison of the novel T311 antibody (anti-tyrosinase) with S-100, HMB-45 and A103 (anti-melan-A). J Clin Pathol 2001;54:196-200.

⁴Xu, X., Chu, A. Y., Pasha, T. L., Elder, D. E., Zhang, P. J. Immunoprofile of MITF, tyrosinase, melan-A, and MAGE-1 in HMB45- negative melanomas. Am J Surg Pathol 2002;26:82-87.

⁵Granter, S.R., Weilbaecher, K.N., Quigley, C., Fletcher, C.D. and Fisher, D.E. Microphthalmia transcription factor: not a sensitive or specific marker for the diagnosis of desmoplastic melanoma and spindle cell (non- desmoplastic) melanoma. Am J Dermatopathol 2001;23:185-9.

⁶Busam KJ, Kucukgol D, Sato E, Frosina D, Teruya-Feldstein J,Jungbluth AA Immunohistochemical Analysis of Novel Monoclonal Antibody PNL2 and Comparison With Other Melanocyte Differentiation Markers. Am J Surg Pathol 2005; 29:400-406

This page last revised 17.3.2005.