Hi,
    The main problem we ran into with oxidizing the melanin with Potassium
Permanganate (KMnO4 for short <-- yes I am that lazy) and Oxalic acid or with
Hydrogen Peroxide was that the sections fell off frequently. If you do this use
a dilute KMnO4, 0.5% at most. I have read an article about Azure B and know of a
lab that uses it. I could get more information on it for you if you want. It
seems to work for them.
Amos Brooks

Mike or Carol Schreiber wrote:

> Dear Histonetters,
>     How is anybody dealing with heavy deposits of Melanin pigment in (skin)
> tissue that is to be stained for HMB-45 and/or S-100? We are using DAKO's
> Envision+/DAB+ detection system, on the DAKO autostainer.  Will a Melanin
> Bleach procedure  using Potassium Permanganate and Oxalic Acid adversely
> affect subsequent immunostaining? I read something about using Azure-B as a
> counterstain instead of Hematoxylin, which is supposed to stain the melanin
> a green-blue thus differentiating it from the brown staining of the DAB
> chromogen. Has anybody tried this?  Thanks for any help you can give me with
> this problem.
>
>     Mike Schreiber HT(ASCP)
>     Three Rivers Pathology
>     Roseville, Minnesota