NGFR-positive desmoplastic melanomas with focal or absent S-100 staining: Further evidence supporting the use of both NGFR and S-100 as a primary immunohistochemical panel for the diagnosis of desmoplastic melanomas.
The histologic diagnosis of desmoplastic melanoma can be challenging in circumstances in which biopsy specimens are small, or there are unsuspected clinical settings, re-excision scars, and unusual sites. This is particularly true when the overlying junctional component is absent or the spindle cells lack melanin pigment. In these instances, the importance of immunohistochemistry cannot be overemphasized. S-100 protein is the primary immunohistochemical stain used for this purpose, with a sensitivity approaching 90%. HMB-45, although a more specific marker for melanocytes, is less sensitive and often negative in these cases. In addition, NGFR, a marker of Schwannian differentiation, has been shown to be a useful confirmatory stain for desmoplastic melanoma, with staining intensity comparable with, or better than that of S-100 protein. We report 2 cases of desmoplastic melanomas that stained only focally and weakly with S-100 protein, but showed diffuse and intense staining with NGFR. In both cases, S-100 staining could have been interpreted as non-confirmatory, thus misguiding the diagnosis. We suggest that NGFR can be a useful complementary marker to S-100 in those desmoplastic melanomas in which staining for S100 protein is only focal or weak.
Radfar
Arash
A
Dermatopathology Section, Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts 02118, USA. aradfar@bu.edu
Stefanato
Catherine M
CM
Ghosn
Samer
S
Bhawan
Jag
J
D000368:Aged; D001132:Arm / Q000473:pathology; D014408:Biomarkers, Tumor / Q000032:analysis; D005260:Female; D006801:Humans; D018327:Hutchinson's Melanotic Freckle / Q000473:pathology; D007150:Immunohistochemistry; D008545:Melanoma / Q000175:diagnosis / Q000473:pathology*; D009419:Nerve Tissue Proteins / Q000032:analysis*; D009669:Nose Neoplasms / Q000473:pathology; D017475:Receptors, Nerve Growth Factor / Q000032:analysis*; D009418:S100 Proteins / Q000032:analysis*; D012878:Skin Neoplasms / Q000175:diagnosis / Q000473:pathology*
D014408:Biomarkers, Tumor; C484065:NGFR protein, human; D009419:Nerve Tissue Proteins; D017475:Receptors, Nerve Growth Factor; D009418:S100 Proteins