Squamous Cell Carcinoma of the External Auditory Canal and Temporal Bone: An Update

Abstract

Squamous cell carcinoma (SCC) is the most common primary malignancy to affect the temporal bone, including primary cutaneous SCC of the pinna, external auditory canal, middle and inner ear. This anatomically complex region generates complicated three-dimensional specimens that can be a challenge for macroscopic and microscopic pathologic assessment. A universally accepted staging classification for these malignancies is still to be established. A brief summary of the regional anatomy, etiology and epidemiology, presentation and diagnosis, radiologic assessment and treatment follows with a review of the pathologic assessment of the different types of specimens generated and an update on staging for SCC of the temporal bone.

Keywords: External auditory canal; Macroscopic examination; Middle ear; Squamous cell carcinoma; Staging systems; Temporal bone.

Fig. 1

Schematic diagram of the external auditory canal, middle and inner ear

Fig. 2

Normal hematoxylin and eosin stained histology of a cartilaginous lateral one-third (inset: high power view of squamous epithelium, hair follicles and distinctive ceruminous glands) and b bony medial two-thirds of external auditory canal (inset: high power view of squamous epithelium to underlying bone)

Fig. 3

Schematic diagram of the medial wall of the middle ear; representing the pathway of the facial nerve

Fig. 4

Otoscopic views; a and b squamous cell carcinoma of the external auditory canal is associated with ulceration and inflammation. The edema and tissue friability makes examination painful and visibility poor

Fig. 5

Hematoxylin and eosin stained histopathology of selected external ear canal malignancies; a external auditory canal with moderately differentiated squamous cell carcinoma, b poorly differentiated squamous cell carcinoma, c basal cell carcinoma (inset: high power view of nested, haphazardly arranged basaloid tumor cells with peripheral palisading), d adenoid cystic carcinoma showing a typical tubular pattern, with pseudoglandular spaces containing excess basement membrane material lined by luminal cells with dark, angular nuclei and surrounded by bland myoepithelial cells

Fig. 6

Hematoxylin and eosin stained histopathology of selected benign destructive processes; a cholesterol granuloma, b cholesteotoma

Fig. 7

a Schematic diagram demonstrating the anatomic structure included in a sleeve resection and b specimen photo of sleeve resection

Fig. 8

a Schematic diagram demonstrating the anatomic structures included in a lateral temporal bone resection and b specimen photograph of oriented right lateral temporal bone resection with the external component (left) and excision of bony external auditory canal (right)

Fig. 9

a Schematic diagram demonstrating the anatomic structures included in a subtotal temporal bone resection, b specimen photograph of contiguous pinnectomy and neck dissection oriented on a cork board (left) and posterior view of pinnectomy with underlying temporal bone (right) for metastatic squamous cell carcinoma involving a post auricular lymph node (arrow), c axial slices from superior to inferior demonstrating metastatic squamous cell carcinoma in post auricular lymph node (28 mm in maximum dimension). d (i) The styloid process, (ii) the mastoid tip, D (iii) facial nerve with suture indicating the point of exit from the stylomastoid foramen