Chronic otomastoiditis (COM) should be considered a separate entity from acute otomastoiditis, and is thought to be primarily due to Eustachian tube dysfunction as demonstrated in this case secondary to enlarged nasopharyngeal adenoids. 

Chronic otomastoiditis (COM) is persistent or recurrent inflammation of the middle ear and mastoid air cells lasting for a minimum of 12 weeks.

The term encompasses a number of conditions:

• middle ear effusion,atelectasis,granulation tissue 
• tympanic membrane retraction, thickening, perforation or calcification (myringosclerosis)
• mastoid air cells opacification and sclerosis
• post inflammatory ossicular fixation or noncholesteatomatous ossicular erosion
• cholesterol granuloma or acquired cholesteatoma