The pop star shared a black and white image, showing her sitting at a table with all her siblings during an evening out, taken by photographer Bruce Weber in 1986.

It was a high point in her career with all five singles from her third studio album True Blue - Live to Tell, Papa Don't Preach, True Blue, Open Your Heart and La Isla Bonita - all going to number one in America or the UK.

Thanking Anthony for the part he played in her life, the 64-year-old singer wrote: "Thank you for blowing my mind as a young girl and introducing me to Charlie Parker, Miles David, Buddhism, Taoism, Charles Bukowski, Richard Brautigan, Jack Kerouac, expansive thinking, outside the box.

"You planted many important seeds."

Madonna and Anthony grew up with their other siblings - Martin, Paula, Melanie, Christopher, Jennifer and Mario - in Michigan. In 1978 Madonna left to pursue a dance career in New York.

As the eldest boy of the family he had been named after his father, while Madonna, as the eldest girl was named after her mother.

Later on Instagram, Madonna shared some behind-the-scenes footage from rehearsals of her upcoming The Celebration global world tour to mark her 40th anniversary, which she announced in January.

She wrote alongside the video, which shows her working with dancers on stage: "Thank God I have my creative life to inspire me and keep me going," along with a "grateful" hashtag.

Musician Joe Henry, who is married to Madonna's sister Melanie, had first shared the news of his brother-in-law's death on Instagram along with a black and white photo of him.

He wrote: "My brother-in-law, Anthony Gerard Ciccone, exited this earthly plane last evening.

"I've known him since I was 15, in the spring of our lives in Michigan so many years now gone.

"Anthony was a complex character; and God knows we tangled in moments, as true brothers can. But I loved him, and understood him better than I was sometimes willing to let on."

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The cause of death was not revealed. However, he was known to have struggled with alcoholism and was reportedly homeless for many years.

He had at times been estranged from his family, and had also spent time living at a rehabilitation facility.

Goodfellas actress Debi Mazar was among those paying tribute to him.

"I have such fond memories of time spent with Anthony back in the late 80's. A real Renaissance Man," she wrote on Instagram.