PhiliPPine Journal of otolaryngology-head and neck Surgery                                                         Vol. 23 no. 1 January – June 2008

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PhiliPPine Journal of otolaryngology-head and neck Surgery  37

The determination of the presence of acquired cholesteatoma in the middle ear and mastoid 
is one of the most common indications for computerized tomographic (CT) imaging of the 
temporal bone. While the presence of a soft tissue density in the mesotympanum, epitympanum 
or antrum is a feature of cholesteatomatous disease, CT imaging cannot reliably differentiate 
soft tissue densities caused by cholesteatoma, middle ear effusion or fluid completely filling the 
middle ear and mastoid air cell system, granulation tissue, brain, or other soft tissue densities that 
may fill the air-containing space.1,2  Bone erosion is the radiologic sine qua non of a cholesteatoma. 
In the absence of bone erosion, a cholesteatoma may be present but cannot be diagnosed on CT 
imaging studies. One of the earliest abnormalities of a cholesteatoma that can be appreciated on 
a CT scan is erosion of the scutum, which is the medial aspect of the roof of the external auditory 
canal, and where the tympanic membrane attaches superiorly. Scutum erosion is most easily 
seen on coronal CT images.2

Nathaniel W. Yang, MD

Department of Otorhinolaryngology
College of Medicine – Philippine General Hospital
University of the Philippines Manila

Blunting of the Scutum:
A Key Feature in the Radiologic Diagnosis 

of Acquired Cholesteatoma 

Correspondence: Nathaniel W. Yang, MD
Department of Otorhinolaryngology
Ward 10, Philippine General Hospital
Taft Ave., Ermita, Manila 1000
Phone: (632) 526 4360
Fax :    (632) 525 5444
Emai: nwyang@gmx.net
Reprints will not be available from the author.

Figure 1. This is a coronal CT image of a temporal bone with no known 
middle ear pathology. It passes through the temporal bone at the level of 
the cochlea, and uses a bone window algorithm with a window width of 
4,000 H. The scutum can be identified as the sharp-edged superomedial 
border of the external auditory canal (white arrowhead).

Philipp J Otolaryngol Head Neck Surg 2008; 23 (1): 37-38 c  Philippine Society of Otolaryngology – Head and Neck Surgery, Inc.



                                PhiliPPine Journal of otolaryngology-head and neck Surgery                                                          Vol. 23 no. 1 January – June 2008   

38  PhiliPPine Journal of otolaryngology-head and neck Surgery

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ReFeRenceS:
1 Johnson DW, Voorhees RL, Lufkin RB et al. Cholesteatomas of the temporal bone: Role of 

computed tomography. Radiology 1983; 148: 733-737.
2 Weissman JL. Hearing loss. Radiology 1996; 199: 593-611.

Figure 2. This is a coronal CT image passing through the level of the 
internal auditory canal in a patient with known middle ear disease. The 
epitympanum is occupied by a soft tissue density (white arrow). The scutum 
(white arrowhead) is blunted, very much like the tip of a used, unsharpened 
pencil. Clinical examination and surgical findings confirm the presence of 
an acquired cholesteatoma in the epitympanum and mastoid antrum.

Figure 3. This is a coronal CT image passing through the level of the cochlea 
in a patient with chronic middle ear effusion. The tympanic membrane 
was intact, with no evidence of attic retraction pockets. The CT scan was 
taken four days after myringotomy with aspiration of the middle ear fluid. 
Persistent clear fluid draining from the ear raised the suspicion of a CSF 
leak. This scan was radiologically interpreted as a case of cholesteatoma, 
although the scutum is not blunted (white arrowhead), and clinical 
examination did not show any evidence of such pathology. This case 
illustrates the need for clinicians to be vigilant in corroborating a radiologic 
diagnosis of cholesteatoma.