The reality TV star, 34, is recovering after undergoing an operation to remove the tumour, which measured 12cm.
Wright said he was initially told not to worry after discovering a lump in his “breast/armpit area”, but returned to doctors after he noticed it growing.
In an Instagram post, he shared a photo of the lump alongside a photo of the 12cm tumour he had removed. He said it had “been a tough call whether or not to speak about this”.
He continued: “One part of me wants to keep something like this private and the other part is thinking, if I can help/potentially save one person, well…. this is the right thing to do.
“I saw a doctor who passed it on as ‘a fatty lump that doesn’t need any treatment’ so I just left it,” he said, adding: “I saw another specialist who happens to be a breast consultant for a second opinion.”
Wright explained: “He was certain after seeing an ultrasound scan that it was a LIPOMA (a BENIGN soft tissue tumour). However with it being rather large, he had a tiny bit of concern that it has/could turn in to a SARCOMA (a cancerous malignant tumour).”
Wright said that, after having an MRI, he underwent surgery as a SARCOMA specialist “did not want to rule out the worst because of the speed and the size of growth”.
He explained that the tumour will be sent off for testing, telling his followers: “This top doctor is certain from his incredible experience that we have done the job and there is nothing sinister to worry about. So I’m all good.
“MORAL OF THE STORY: If you notice anything that doesn’t look or feel quite right. Don’t leave it.”
Wright, best known for appearing in The Only Way is Essex, has been praised on Twitter for sharing his experience.
He revealed that his uncle Eddie died in March, aged 66, after having the illness for eight weeks. He told The Sun: “I struggle with this because it didn’t have to happen. Why did this virus have to take him?”
The TV personality is married to former Coronation Street actor Michelle Keegan.