 |
| Choleteatoma |
Choleteatoma
Cholestesteatoma="Skin hn d wrong place"
it has 2 parts
a=matrgx
-made of keratinised squamous epithlm resting on d thin stroma of fibrous tissue
b=central white mass
-consisting of keratin debris produced by matrix
also caled epidermosis/keratoma
* Origin of cholestma
1=presence of congenital cell rests2=invagination of tympanic membrne 4m d attic in form of retraction pocket=Wittmaacks theory
3=basal cell hyperplasia. The basal cels of germinal layer of skin proliferate due 2 infection=Ruedis theory
4=epithelial invasion. The epithelium 4m d meatus grows in2 middle ear through a pre-existing perforation=Habermans theory
5=metaplasia. Middle ear mucosa undergoes metaplasia due 2 repeated perforation and convert in2 squamous type=Sades theory
* Classification
1. Congenital
- arises 4m d embryonic epidermal cell- sites: middle ear,petrous apex,cerebellopontine angle
- presents as white mass behind d intact tympanic membrane and causes conductive hearing loss
2. Acquired primary
- there is primary bcos there no history of previous otitis media/perforation- theories :
a. invagimation of pars flaccida
- persistent -ve pressure in d attic causes a retraction pocket which accumulate keratin debris
b. basal cell hyperplasia
c. squamous metaplasia
3. Acquired secondary
- there is already pre-exisisting perforation in d pars tensa- always asociated with d posterosuperior marginal or sometimes central perforation
- theories :
a. migration of squamous epithelium
b. metaplsia
* Expansion of cholestoma
- 4m d middle ear invade d surrounding structure and follows d path of least resistance and then enzymatic bone distruction- attic cholstoma may extends backwards 2 aditus,antrum,mastoid, downward in2 mesotympanum and medialy surrounds d incus
EmoticonEmoticon