Which Specialist Is To Be Consulted For Bruises And Dark Circles On Penis?

My husband is 40years and 2 weeks back he noticed small bruises in his penis and a dark circle also. We met a dermatologist. He has advised us to take blood sugar and lipid profile and prescribed a moisturere for application and anotehr tablet for itching sensation and asked us to come after 10 days. Sugar is normal. On lipid profile except Triglycerides, others are normal. My question is for this problem approaching a dermatologist is correct or do we need to approach any other specialist? Is there any serious cause of worry or is it a common problem and can be treated by medicine. Some say circumsition will be a remedy for this....(Not very sure)