post auricular swelling with mastoid bone involvement most commonly occurs as a cranial complication of chronic or acute suppurative otitis media. Aim of this study, to detect etiology of postauricular swelling with mastoid bone involvement. This is a retrospective study which was done on all patients whom underwent mastoidectomy for post auricular swelling with mastoid bone involved in El Minia University Hospital from January 2014 to June 2017. A total of 49 patients were identified in this study, 23 males and 26 females, their ages ranged 5-28 years old with a mean of 25.8 years old. Group A: these were 45 patients with a history of otorrhea (chronic suppurative otitis media), of 3 months to 4 years duration. Group B: these were four patients without any history of otorrhea. Two patients diagnosed as acute otitis media, one patient diagnosed as Langerhans cell histiocytosis and one patient diagnosed as fungal mastoiditis. chronic suppurative otitis media is the most common causes of postauricular swelling. Langerhans cell histiocytosis of the temporal bone and fungal mastoiditis are considered a rare presentation of postauricular swelling.
