The 59-year-old star found the growth and after seeking medical advice he was told by his doctor that the lump must be removed as soon as possible and he is to fly out to Memphis next week to undergo an operation.
Memphis otolaryngologist Neal S. Beckford, M.D. said: "Mr. Gest is flying to Memphis and will have the operation to remove the tumour on his neck immediately after his arrival next week. We expect Mr. Gest to have made a full recovery by mid-January 2013."
David`s health problems mean he has had to walk away from his role as Frankenstein`s Monster in adult British pantomime `A Nightmare On Lime Street` which is running through December and January at the Royal Court Theatre in Liverpool, North West England.
The concert promoter had missed the opening week of the play - which also stars Michael Starke and Mark Moraghan - because of a bout of severe viral gastroenteritis and he has now to pull out completely.
In a statement, Kevin Fearon, producer of the production and Chief Executive of the Royal Court Theatre, said: "We are all very disappointed to lose David from the show but we agreed that his health must come first. He was working hard throughout rehearsals and we were looking forward to having him on stage here. The cast, crew and staff of the theatre would all like to wish him well with his operation."
David - who is a former contestant on `I`m A Celebrity... Get Me Out of Here! - is devastated he has had to quit the show after working so hard to prepare for his theatrical debut but he has had to accept his doctor`s advice.
He told BANG Showbiz: "I was really looking forward to singing in this wonderful play written by Fred Lawless. I have worked with a fabulous musical director named Howard Gray who has taught me how to sing and phrase and made it a brilliant experience for me. But I have no choice."
Before he heads to Memphis for his operation, David will be honoured for his Humanitarian Services on behalf of the homeless in Liverpool on 09.12.12 by The Whitechapel Centre who help homeless people aged 16 and over get their lives back on track.
The star-studded gala musical concert and dinner honouring David will take place at The Palm House in Sefton Park, Liverpool and the evening will be hosted by `Coronation Street` star Kym Marsh.
Entertainment for the evening will be provided by magician Dynamo and singers Deniece Williams, Russell Thompkins, Jr. and Sheila Ferguson.
David - who was close friends with Michael Jackson - is due to embark on his `Legends of Soul Spectacular` tour of the UK from February 1, 2013.