Benign (harmless, inoffensive) is an adjective, not an adverb.
A sentence using the adverb, benignly.
"He smiled benignly at the bullies, knowing that he would have his revenge on them in a few hours."
Luckily, the tumor was benign.
he was a little benign
Correctly is the adverb in that sentence.
That sentence does not have an adverb.
He is known to be a benign supervisor.
"we were so happy to find out that John's tumour was benign"Luckily, the tumor was benign.
The adverb in the sentence is where.
Subject of the sentence Verb of the sentence Adverb of Manner Adverb of Place Adverb of Frequency Adverb of time Purpose
I have several harmless, or benign moles on my skin.
The tumor was benign; it was not harmful for now.
A tumor was removed from Billy's lung, but thankfully it was benign.
Let's posit our situation to the benign camp director.