HMB-45 may be a more sensitive maker than S-100 or Melan-A for immunohistochemical diagnosis of primary oral and nasal mucosal melanomas.
BACKGROUND
Primary mucosal melanomas (MMs) of the head and neck are a rare entity. Melanomas with characteristic melanin-pigmented tumor cells are easy to diagnose, but those without melanin-pigmented tumor cells, amelanotic melanomas, are difficult to identify and need immunohistochemistry (IHC) to confirm the final diagnosis. In this study, we examined the expression of three melanocytic differentiation markers, HMB-45, S-100, and Melan-A in primary oral and nasal MMs. We tried to evaluate whether HMB-45, S-100, and Melan-A were useful for diagnosis of primary oral and nasal MMs and to find out which marker was the best of the three.


METHODS
This study used IHC to examine the expression of HMB-45, S-100, and Melan-A in 17 formalin-fixed paraffin-embedded specimens of primary oral and nasal MMs. The staining intensities (SIs) and labeling indices (LIs) of HMB-45, S-100, and Melan-A in 17 MMs were calculated and compared between any two markers.


RESULTS
Immunostaining results showed that the positive rate was 94% (16 of 17) for HMB-45, 88% (15 of 17) for S-100, and 71% (12 of 17) for Melan-A in 17 MMs. The SI of HMB-45 was significantly higher than that of S-100 (P = 0.0011) or of Melan-A (P = 0.0034). In addition, the mean LI of Melan-A (59 +/- 43%) was significantly lower than that of HMB-45 (83 +/- 28%, P = 0.0065) or of S-100 (79 +/- 33%, P = 0.0237).


CONCLUSIONS
Our results indicate that both HMB-45 and S-100 show a high positive rate and LI in MMs and therefore may be good markers for immunohistochemical diagnosis of primary oral and nasal MMs. In addition, HMB-45 may be a more sensitive marker than S-100 because HMB-45 shows a significantly higher SI than S-100 in this study.
Yu
Chuan-Hang
CH
Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University, Taipei.
Chen
Huang-Hsu
HH
Liu
Chia-Ming
CM
Jeng
Yung-Ming
YM
Wang
Jeng-Tzung
JT
Wang
Yi-Ping
YP
Liu
Bu-Yuan
BY
Sun
Andy
A
Chiang
Chun-Pin
CP
D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D002467:Cell Nucleus / Q000473:pathology; D004396:Coloring Agents; D003593:Cytoplasm / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D058965:MART-1 Antigen; D008297:Male; D008544:Melanocytes / Q000473:pathology; D008545:Melanoma / Q000175:diagnosis* / Q000276:immunology; D058950:Melanoma-Specific Antigens; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology; D009062:Mouth Neoplasms / Q000175:diagnosis* / Q000276:immunology; D009297:Nasal Mucosa / Q000473:pathology; D009363:Neoplasm Proteins / Q000032:analysis*; D009669:Nose Neoplasms / Q000175:diagnosis* / Q000276:immunology; D009418:S100 Proteins / Q000032:analysis*; D012680:Sensitivity and Specificity
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D004396:Coloring Agents; D058965:MART-1 Antigen; C548667:MLANA protein, human; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D009418:S100 Proteins