What Could Red Ulcer Like Formations On Penis Suggest?

hi, i have got some redness on the penis and ulcers like formations on my foreskin. one dermatologist diagnosed it as FDE9fixed drug eruptions). he gave me steroids (omnacortil 10) and also an injection of depomedrol. since there was no change in the condition, went to another dermatologist for second opinion. he thot it was herpes genetalia and gave me a dose ofzovirax. now, after a week he has suggested biopsy. i am worried. what kinds of diseases can be diagnosed by doing biopsy