Brief Answer: unlikely to be fungal....adaptation rather! Detailed Answer: Hi and thank you so much for this query. I am so sorry to hear about this disturbing finding on the shaft of your penis. From the information you have provided, i am afraid this callous is probably an adaptation to the mechanical friction that you have been applying to this part of the penis during masturbation. This is also likely because you don't use an appropriate lube that should reduce these forces and prevent any adaptation changes. In the same way our soles and palms become thick as adaptations to their constant aggression, so too any part of the body can develop such hardened and thickened skin. Avoid any further masturbation and allow it to rest.. It may never return immediately but it would not get any further worse. Over time, it would become better. I hope you find this helpful. Thank you for using our services and please feel free to ask for more information or clarification if need be. I wish you well. Thanks. Dr. Ditah, MD

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