Mahbod Moghadam says tumour made him irritable, to the point of telling Mark Zuckerberg to 'suck my dick'; meanwhile the site is taking step to become fully licensed

Mahbod Moghadam, co-founder of popular rap lyrics website RapGenius, has blamed a rash of aggressive behaviour, including telling Facebook founder Mark Zuckerberg and investor Warren Buffett to "suck my dick", on an unidentified brain tumour.

In an interview with Fast Company, Moghadam describes discovering problems with his left hand, which began to tremble uncontrollably, and found it difficult to exercise; he later described "an evil hum in my head". The debilitation changed his personality for the worse. He verbally abused his coworkers, his girlfriend broke up with him, and he engaged in a series of public outbursts. He sent a violently sexually abusive tweet to the editor of music magazine Spin, attacked Zuckerberg after the Facebook founder asked him to remove a picture of him and rapper Nas, and made the slur against Buffett while setting up a competition for tracks that dissed the billionaire investor.

But following emergency surgery, Moghadam said: "It was a fetal benign tumor, and - honestly I think this - it was the cause of me acting like an asshole."

RapGenius has become hugely popular with its Wikipedia-like system of crowdsourced lyrics and opinion, where users can upload lyrics but also comment on their meaning; rappers themselves have become users, posting video explanations of their work. It was founded in 2009, and received $15m of investment last year from Andressen Horowitz, the venture capital firm famous for supporting successful startups including Facebook, Twitter, Groupon and Airbnb. The company plans to move into rock lyrics, news, and poetry – Moghadam has said that he wants to annotate the entirety of War And Peace.

Earlier this week, the National Music Publishers' Association in the US requested the site be taken down, because it was hosting intellectual property without a licence. Their argument is that the site and its competitors must pay publishers for hosting lyrics, effectively giving royalties to the lyric writers for their work. Ilan Zechory responded by defending the site's "interactive, vibrant art experience created by a community of volunteer scholars" in the New York Times, but the site is now taking steps to become fully licensed. They signed a deal with Sony/ATV Music Publishing "earlier this year", and have said they'll continue to work with other publishing companies.