Risks of skin biopsy on urethra

there has been a bump on the tip of my urethra for 9months now. the skin around the penis head has also been red and irritated. the diagnosis was lichen planus but they arent sure. bloodwork for something infectious or std related has been negative..topical corticosteroids have not worked. the next and last step is a biopsy on hte tip of the urethra. what are possible risks? will it look much different, and if the area  was previously treated with topical steroids, will it give a diagnosis? how long would it take for pain to subside when peeing?