Michael is 42 years old and has been referred to ENT as he has had a discharging left ear for several months. He has had multiple courses of antibiotics, but the symptoms persist. The discharge has no odour. Michael says his mother tells him he had recurrent ear infections as a child. He feels his hearing in the left ear has gradually got worse over the last few months. Past medical history is unremarkable.
On examination today, there is purulent discharge in the left ear canal. You note a retraction pocket in the tympanic membrane and some granulation tissue.
What is the most likely diagnosis?