Melanin bleaching in argyrophilic staining of AgNORs in pigmented lesions: a morphometric evaluation.
OBJECTIVE
To establish a procedure that can effectively bleach melanin from pigmented lesions without affecting quantification of argyrophilic staining of nucleolar organizer regions (AgNORs).


METHODS
Twenty banal compound nevi, five from each of nonpigmented, slightly pigmented, moderately pigmented and heavily pigmented groups, were bleached by 10% H202 for periods of 0 (nonbleached controls) and 24 hours. AgNOR size and count parameters of nevomelanocytic nuclei were measured by video image analysis. Melanin bleaching using KMnO4 was also investigated.


RESULTS
In all lesions treated with 10% H202 for 24 hours, the melanin was bleached effectively, with no qualitative change in AgNOR appearance. There were no significant differences in mean AgNOR number per nucleus (AgNOR number), mean individual AgNOR size (AgNOR size) or mean percentage of AgNOR area per nucleus (% nuclear area) between nonbleached and bleached sets in both the nonpigmented and slightly pigmented groups. However, disintegration of AgNOR dots was observed in those treated with 1% KMnO4 for 5, 10 and 15 minutes. There were significant decreases in AgNOR size (P = .002) and % nuclear area (P = .003) and increase in AgNOR number (P = .05) in the slightly pigmented group evaluated when treated with 1% KMnO4 for five minutes.


CONCLUSIONS
Melanin in pigmented lesions can be bleached effectively with an H202 procedure without significantly affecting AgNOR staining properties in contrast to bleaching with KMnO4.
Li
Ling-Xi L
LX
Melanoma and Skin Cancer Research Institute, Department of Anatomical Pathology, Royal Prince Alfred Hospital, Camperdown, Australia. lawly@med.usyd.edu.au
Crotty
Kerry A
KA
Palmer
Allan A
AA
Kril
Jillian J
JJ
Scolyer
Richard A
RA
McCarthy
Stanley W
SW
D006861:Hydrogen Peroxide / Q000494:pharmacology; D008543:Melanins; D009508:Nevus, Pigmented / Q000737:chemistry / Q000188:drug therapy / Q000648:ultrastructure*; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D011196:Potassium Permanganate / Q000494:pharmacology; D016622:Silver Staining / Q000379:methods*; D012878:Skin Neoplasms / Q000473:pathology; D013997:Time Factors
D008543:Melanins; D011196:Potassium Permanganate; D006861:Hydrogen Peroxide