Veterinary questions? Ask a Vet for Answers ASAP
I have seen lesions similar to this in hamsters with chronic dermatitis and otitis (often in conjunction with ringworm or mites). These can also be viral. Some of these can fall off on their own after they outgrow the blood supply or the underlying disease has been treated they may resolve. In other cases, if a viral etiology he will need it surgically removed. I would strongly recommend that you have your hamster tested for ringworm and mites, ears checked for infection that led to itchiness and then the abnormal tissue growth, and started on medication appropriate to the underlying issue. These can excoriate from the itching a bleed a lot so I would suggest he be seen sooner than later.
If it is bleeding a lot you can apply pressure or an ice cube in a thin sheet to slow down the bleeding.
For a list of vets in your area that see small mammals see: http://www.aemv.org
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If it is ringworm or polyomavirus or mange, yes all those would be. Ringworm in hamsters is usually zoonotic (people can get it).
If it is a tumor then no. How many hamsters do you have and where are they located in relation to this hamster?
Sorry I see you just have one Robo- how close is the cage?
Okay, if possible, move the Robo into another room, or at bare minimum across the room. If ringworm, highly contagious and the Robo being above is not getting spores showered down. If ringworm is diagnosed from culture, and the dwarf is in a room with carpet it can still be contagious for awhile.
I wish you and your hammies all the best.