Basal cell carcinoma of external auditory canal

Last revised by Mohamed Saber on 14 Apr 2021

The carcinomas of the external auditory canal are unusual with an annual incidence of one per million 1Squamous cell carcinoma is the most common tumor of EAC accounting for 80% of all tumors followed by basal cell carcinoma as the second most common histological type 2,3.

  • canal mass
  • otorrhea
  • otalgia
  • facial paralysis

High resolution computed tomography (HRCT) of the petrous temporal bone CT scan (axial temporal bone and neck, with and without contrast) is used for assessment of EAC bony canal erosion, extension into the middle ear, mastoid part and surrounding soft tissue as well as the extension of the tumor into the dura, cochlea and petrous apex 7,8.

MRI is the modality of choice for evaluating soft tissue involvement of the tumor that shows the loss of signal on T1 weighted images (T1WI) and contrast enhancement 8-10.

MRI with gadolinium is useful when suspicious of the dural invasion or opacification of the mastoid and middle ear (distinguish between tumor and fluid) 8.


T1: tumor confined to the EAC with no evidence of  bony erosion or soft tissue extension

T2: tumor with  not full thickness EAC bony erosion or limited (<0.5 cm) soft-tissue invasion

T3: tumor with full-thickness erosion of the osseous EAC with limited (<0.5 cm) soft tissue involvement or tumor invading the middle ear and/or mastoid, or facial paralysis

T4: tumor with the erosion of the cochlea, petrous apex, medial wall of the middle ear, carotid canal, jugular foramen or dura, or with extensive (>0.5 cm) soft-tissue involvement.

Although the BCCs are known to be locally aggressive but can be non-treatable if intracranial invasion occurs. involvement of the Bony canal may need temporal bone resection, and extended lesions may need pinna resection and reconstruction 6,13,14.

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