The 1979 and Bullet With Butterfly Wings singer posted on social media to show the prominent purple mark on his left arm and hand.

In the caption, he said he supported body positivity movements "because at the end of the day it is about celebrating what makes us 'us'".

The 57-year-old also posted a photo of model Carlotta Bertotti - who has a birthmark on her face - as an example of someone "who has embraced her 'difference' with grace".

He then said: "My whole life I've endeavoured to hide my 'port wine' birthmarks because as you can imagine I was teased unmercifully about them as a child.

"So much so that people who have known me for a decade are shocked when they finally 'see it'."

Corgan added that "even now" he is stopped on the street by people "not because they recognize me but because they think something is wrong with me that requires medical attention".

"Plus the random questions: Is that a burn? Are you sick? Is it contagious? Does it hurt?" he wrote.

"So positive message for the day: Whoever you are, I hope you find peace with who you are because: I would like to know that person and no one else."

According to the NHS and Great Ormond Street Hospital, a port wine stain birthmark is caused by the abnormal development of blood vessels in the skin.

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Port wine stains can become thicker, darken and develop raised bumps and ridges in time.

While they are usually harmless, the NHS says the birthmarks can sometimes develop small blood vessel blisters called papules or pyogenic granulomas, which can bleed easily.