Middle Ear Lesion



Middle Ear Lesion


H. Ric Harnsberger, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Chronic Otitis Media (COM)


  • Acquired Cholesteatoma, Pars Flaccida


  • Congenital Cholesteatoma, Middle Ear


Less Common



  • Acute Otomastoiditis (AOM) with Coalescent Otomastoiditis


  • Acquired Cholesteatoma, Pars Tensa


  • Cholesterol Granuloma, Middle Ear


  • COM with Tympanosclerosis


  • COM with Ossicular Erosions


Rare but Important



  • Rhabdomyosarcoma, Middle Ear


  • Langerhans Histiocytosis, T-Bone


  • Dehiscent Jugular Bulb


  • Aberrant Internal Carotid Artery


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Otoscopic findings often provide critical clues to precise diagnosis of middle ear lesion in child



    • Presence or absence of tympanic membrane (TM) rupture important



      • Pars tensa &/or flaccida acquired cholesteatoma has ruptured TM


    • Color and location of retrotympanic mass may be key to imaging diagnosis


Helpful Clues for Common Diagnoses



  • Chronic Otitis Media (COM)



    • Otoscopy: Thickened tympanic membrane


    • Bone CT: Linear, sporadic middle ear-mastoid tissue; mastoid air cells may be underpneumatized


  • Acquired Cholesteatoma, Pars Flaccida



    • Otoscopy: Rupture or retraction pocket affecting pars flaccida portion of tympanic membrane


    • Bone CT: Nondependent soft tissue filling Prussak space with ossicle and/or bony wall erosions



      • Possible complications: Tegmen tympani, lateral semicircular canal, facial nerve canal dehiscence


  • Congenital Cholesteatoma, Middle Ear



    • Otoscopy: White mass behind intact TM


    • Bone CT: Smooth, well-circumscribed soft tissue mass filling middle ear; often medial to ossicle chain



      • Ossicle erosion often absent


      • Mastoid pneumatization often normal


Helpful Clues for Less Common Diagnoses



  • Acute Otomastoiditis (AOM) with Coalescent Otomastoiditis



    • Otoscopy: Bulging, inflamed tympanic membrane


    • Bone CT: Complete middle ear-mastoid opacification with mastoid trabecular breakdown



      • Hint: Look on soft tissue windows for adjacent postauricular abscess or epidural abscess


  • Acquired Cholesteatoma, Pars Tensa



    • Otoscopy: Ruptured pars tensa portion of TM


    • Bone CT: Meso- and hypotympanic soft tissue mass often extending posteriorly or medially


  • Cholesterol Granuloma, Middle Ear



    • Otoscopy: Blue-black material behind intact TM


    • Bone CT: Middle ear soft tissue mass with minimal bony erosion


    • MR: High T1 and high T2 signal of material in middle ear (ME)



      • Hint: Old blood in cholesterol granuloma creates T1 shortening


  • COM with Tympanosclerosis



    • Otoscopy: Opaque, calcified tympanic membrane


    • Bone CT: Postinflammatory calcifications may affect ossicles, ligaments or TM


  • COM with Ossicular Erosions



    • Otoscopy: Thickened TM without normal ossicle impressions


    • Bone CT: Linear middle ear and mastoid air cell opacifications with partial ossicle absence



      • Long process of incus-lenticular process and stapes hub most commonly affected


Helpful Clues for Rare Diagnoses



  • Rhabdomyosarcoma, Middle Ear



    • Otoscopy: EAC “polyp”


    • Bone CT: Destructive middle ear mass that often affects EAC, ossicles, surrounding bones, overlying dura


  • Langerhans Histiocytosis, T-bone




    • Otoscopy: Postauricular mass common


    • Bone CT: Unilateral or bilateral (30%) destructive T-bone lesions affecting middle ear secondarily



      • Mastoid air cell more commonly affected than petrous apex or inner ear


  • Dehiscent Jugular Bulb



    • Otoscopy: Blue lesion behind posteroinferior quadrant of TM


    • Bone CT: Dehiscent sigmoid plate projects jugular bulb into posteroinferior middle ear cavity


  • Aberrant Internal Carotid Artery



    • Otoscopy: Reddish mass passes across inferior half of TM


    • Bone CT: Tubular lesion passes into posteroinferior middle ear cavity through enlarged inferior tympanic canaliculus



      • Aberrant ICA passes out of middle ear cavity anteroinferiorly by accessing posterolateral margin of horizontal petrous internal carotid artery


Other Essential Information



  • Best imaging tool for middle ear lesion in child: T-bone CT without contrast



    • Thin-section, fat-saturated MR only used for further evaluation of larger lesions involving inner ear, floor middle cranial fossa or sigmoid sinus-posterior fossa


  • Tumor or tumor-like lesions to consider in middle ear of child



    • Rhabdomyosarcoma and Langerhans cell histiocytosis


    • May be difficult to tell these 2 lesions apart


    • Rhabdomyosarcoma, Middle Ear



      • Unilateral; centered in middle ear cavity; may present with EAC “polyp”


    • Langerhans Histiocytosis, T-Bone



      • May be bilateral; centered around middle ear cavity, especially in mastoid; may present as postauricular mass


Alternative Differential Approaches

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Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Middle Ear Lesion

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