Hello thanks!Welcome to Reef2Reef!
That looks like it is possibly an injury, not a primary infection. However, some background information is important to know. Here is a post that outlines some of the information that is helpful to know about your fish and the tank:
Some Helpful Hints When Posting or Responding to Threads in the Fish Disease Treatment and Diagnosis SectionAquarium Fish Disease Problem Solving Determining the best course of action for a problem with your aquarium can be a difficult task. Even advanced aquarists will often need to seek the help of others for complicated issues. Our intent here is to offer expert advice for your fish disease...www.reef2reef.com
Exactly how mine was when I brought it home! Broke a chunk out of my montiMy orange shoulder is like a (friendly) bull in a china shop, constantly knocking into stuff, flipping over frag racks, and just generally busting up stuff in my frag system. Small lacerations were common.
That's not HLLE. As long as the lesion doesn't grow, or start up in new spots, you should be o.k. The other issue is - if this is a bacterial infection (likely) you would need a treatment tank to dose antibiotics in.I was just more concerned of it being hlle because I've never had that happen before so I'm not to sure how to diagnose the early stages.