Hi welcome to Ask The Doctor,
There might be many reasons for this. This may be related to circumcision. As the head of the penis is naturally an internal organ. It is covered with a mucous membrane.
Removing the foreskin causes the head to do something called "keratinise", which means it dries out and becomes the texture of outer skin. The penis is made up of plenty of blood vessel with connective tissue holding them covered by a layer of thin skin. The color of the glans can range from pink to light blue to purplish blue to purple. The changes may vary depending on the erectile state of the penis. This might be a normal case but still it is better to consult a doctor. All the best.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.