According to the U.S. National Library of Medicine and the National Institutes of Health or NIH, the mastoid process is a prominent, bony bump located just behind the outside ear, and although the size of the mastoid process varies between individuals, it's typically larger in males than females 1. The mastoid process is the site of attachment for numerous muscles, and its underlying structures may be susceptible to certain medical conditions or diseases.

Mastoiditis

Mastoiditis is a disease associated with the mastoid. According to the University of Maryland Medical Center or UMMC--a teaching hospital based in Baltimore, Maryland--mastoiditis is an infection of the mastoid bone. The disease is often caused by a middle ear infection or acute otitis media. The mastoid bone possesses an underlying, honeycomb-like structure, and when the mastoid becomes infected, infected materials fill its pockets or air cells. The UMMC states that mastoiditis occurs more frequently in children, and that mastoiditis used to be one of the most common causes of death among children. According to the UMMC, mastoiditis can be challenging to treat because medications may not penetrate deep enough into the mastoid bone to be effective.

Mastoid Cancer

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Mastoid cancer is a disease of the mastoid 2. According to a 2005 study by O. A. Lasisi and colleagues published in the "Ghana Medical Journal," malignant or progressive and harmful tumors of the mastoid are rare, but of the tumors that do manifest in the mastoid, most are squamous cell carcinomas 2. According to EarSurgery.org, malignant mastoid tumors are often found in people with chronic or long-term mastoid infection.

Cholesteatoma

Cholesteatoma is a disease associated with the mastoid. According to the Marshfield Clinic--a Wisconsin-based health care system--cholesteatoma is an ear disease in which a skin cyst invades a person's middle ear and mastoid, and although the cyst is not cancerous, it may erode nearby tissue and permanently damage the ear. The Marshfield Clinic states that a cholesteatoma or destructive and expanding growth forms when a person's Eustachian tube--the tube that links the pharynx to the middle ear--does not open enough to equalize pressures in the middle ear, which in turn causes the ear drum to retract, forming a pocket that may become trapped in the ear as a skin cyst. Common symptoms associated with cholesteatoma include gradual hearing loss, ear discharge and a history of ear infections. Cholesteatoma surgery may involve one or more of the following procedures: tympanoplasty, mastoidectomy and ossiculoplasty, among others.