Circumsion which cuts off tzaraat, as an Unintentional [Transgressive] Byproduct of that act: Shabbat 133a
A general statement that circumcision takes precedence over the prohibition against cutting off tzaraat: Nedarim 31b
Where the circumcision will cut off tzaraat, and the circumcision is on the 8th day: Shabbat 132b-133a
Where the circumcision will cut off tzaraat, and the circumcision is After the 8th day: Shabbat 132b-133a
Circumcision of a metzora who is a minor, but more than 8 days old: Shabbat 132b