Brief Answer:
Vitiligo or Post inflammatory depigmentation.

Detailed Answer:
Hello,
Welcome to XXXXXXX
Thanks for your query.

I have gone through your and understand your concern.

White spot seems like Vitiligo or post inflammatory depigmentation to me.

But it can also be due to Post inflammatory depigmentaion by repeated trauma to frenulum of penis.

Because both vitiligo and post inflammatory depigmentation are very common in frenulum of penis.

Vitiligo is a condition where the body’s own immune system attacks the pigment forming cells of the skin leading to white patches.
If you are my patient, i would initially prescribe topical steroid cream and oral antioxidants for a couple of months.
Most of the patients usually respond to steroid cream on local application.

If your white spot is still there, then i will advise for small biopsy and microscopic examination of the tissue.

In vitiligo, there is a complete absence of pigment forming melanocyte cells is the usual finding.

Hope this helps.
Please reply for further queries.
Wishing you good health.

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Brief Answer:
Either infection of trauma. better upload photo.

Detailed Answer:
Hello,

I suspect it to be either infection or trauma.
Because vigorous sex or masturbation may cause small trauma with swelling and water blister.

It may also be due to infection.
Please upload a new image with blister.

Hope this helps.
Please reply for further queries.
Wishing you good health.

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Brief Answer:
Edema. Minor injury. Avoid masturbation frequently

Detailed Answer:
Hello,

As it swells up after masturbation, i suspect it to be an edema not a blister.

The swelling may be due to very minor injury in inner of frenulum of penis.
This lead to fluid oozing out and collect under the skin in frenulum of penis.

I advise you to avoid frequent masturbation and vigorous activity while masturbation.

Hope this helps.
Please reply for further queries.
Wishing you good health.

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