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Squamous Cell Carcinoma of the Temporal Bone
A Radiographic-Pathologic Correlation
M. Boyd Gillespie, MD;
Howard W. Francis, MD;
Nelson Chee, MD;
David W. Eisele, MD
Arch Otolaryngol Head Neck Surg. 2001;127:803-807.
ABSTRACT
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Objective To assess the utility of a previously proposed staging system for patients
with primary squamous cell carcinoma of the temporal bone.
Methods Retrospective chart review of 15 patients treated for squamous cell
carcinoma of the temporal bone over a 13-year period at an academic tertiary
referral center. A review of the medical and surgical records, radiographic
studies, and surgical pathology reports allowed for an evaluation of the University
of Pittsburgh staging system. Outcome analysis was performed on 13 patients
with more than 24 months of follow-up.
Results Radiographic and surgical pathology staging according to the University
of Pittsburgh staging system correlated in 11 (73%) of 15 cases. The radiographic
staging system was more accurate for larger (T3/T4) tumors than for smaller
(T1/T2) tumors (83% vs 67%). When compared with patients with no evidence
of disease, nonsurvivors were more likely to present with otalgia (67% vs
43%), facial nerve paralysis (33% vs 0%), and T3/T4 tumors (100% vs 14%).
Conclusions Pathologic staging by the University of Pittsburgh staging system closely
correlates with patient outcome and is more sensitive than preoperative radiographic
staging. Prognosis in squamous cell carcinoma of the temporal bone is largely
determined by the extent of local disease at the time of presentation.
INTRODUCTION
PRIMARY SQUAMOUS cell carcinoma of the external auditory canal and temporal
bone is an uncommon malignancy with an estimated incidence of 5 cases per
million population.1 The best methods of tumor
staging and treatment are still a matter of debate. Adequate outcome data
have been difficult to obtain from the medical literature owing to the small
number of patients with the disease, the variety of staging classifications
used, inconsistency in treatment methods and terminology, inclusion of tumors
of various histopathologic characteristics, poor patient follow-up, and the
lack of prospective randomized trials.1
The goal of tumor staging is to group together patients with a similar
extent of disease prior to treatment. An accurate staging system facilitates
the comparison of treatment outcomes for patients with similar disease severity
treated by different modalities and institutions. Conclusions can then be
made with regard to treatment efficacy and disease prognosis. Currently, there
is no universally accepted staging system for malignancies of the temporal
bone.2
The University of Pittsburgh staging system for primary squamous cell
carcinoma of the external auditory canal was proposed in 1990 as a straightforward,
accurate, reproducible system for classifying disease prior to treatment.3 Owing to the rarity of the tumor, the pooling of data
from multiple institutions using the same tumor classification scheme was
advocated.3 Several studies have since affirmed
the utility of the University of Pittsburgh staging system.4-6
The present study reviews the treatment and outcome of 15 patients with
primary squamous cell carcinoma of the temporal bone treated at Johns Hopkins
Hospital, The Johns Hopkins University School of Medicine, Baltimore, Md,
over a 13-year period. The goal of the review is to assess the utility of
the University of Pittsburgh staging system, to identify patient and tumor
factors that may have prognostic significance, and to report our experience
with this uncommon aggressive malignancy.
POPULATION, MATERIALS, AND METHODS
The medical and surgical records of 15 patients with primary squamous
cell carcinoma of the temporal bone treated at the Johns Hopkins Hospital
from January 1, 1986, through December 31, 1998, were reviewed. The hospital
surgical pathology databank was searched to identify patients with a diagnosis
of carcinoma of the temporal bone. To be included in the study, patients had
to (1) have primary squamous cell carcinoma originating within the temporal
bone, and (2) have undergone computed tomographic (CT) imaging and primary
surgical resection at our institution. Fifteen patients were identified who
met these criteria. Clinical information on these patients was obtained from
a review of the hospital and outpatient charts and the electronic patient
record, which included radiology reports, operative notes, pathology reports,
discharge summaries, and outpatient clinical follow-up examinations. Factors
evaluated included patient demographics, presenting symptoms, physical examination
findings, radiographic findings, surgical treatment, method of reconstruction,
surgical complications, histopathologic findings, and the use of postoperative
radiation therapy.
Three types of surgical resection were performed in this series. Local
resection is defined as any resection less than an en bloc lateral temporal bone resection, including resection of external canal
skin and modified or radical mastoidectomy. Lateral temporal bone resection
consisted of a formal en bloc removal of the bony
and cartilaginous external auditory canal, tympanic membrane, malleus, and
incus with identification and preservation of the facial nerve along its vertical
segment. Subtotal temporal bone resection involved the removal of the lateral
temporal bone with the additional resection of a portion of the otic capsule
with preservation of the petrous apex and carotid artery. No total temporal
bone resections were performed in this series.
The tumors of the 15 patients were staged using the University of Pittsburgh
staging system for squamous cell carcinoma of the external auditory canal,
both on the basis of the preoperative temporal bone CT findings and the intraoperative
and surgical pathologic findings (Table
1). A comparison of possible prognostic factors was performed on
the 13 patients with sufficient follow-up. Patients were considered to have
no evidence of disease if they had clear pathologic margins and no evidence
of recurrence after at least 24 months of follow-up.
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Table 1. University of Pittsburgh Staging System for Squamous Cell
Carcinoma of the Temporal Bone
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RESULTS
Fifteen patients received treatment for primary squamous cell carcinoma
of the temporal bone at the Johns Hopkins Hospital between 1986 and 1998.
The study group consisted of 11 women and 4 men. Patient ages ranged from
48 to 77 years, with a mean age of 66 years. The most common presenting symptoms
included otorrhea (11 [73%]), otalgia (8 [53%]), and hearing loss (5 [33%]).
Less commonly, the patient presented with facial paralysis (2 [13%]) or vertigo
(1 [7%]).
All patients underwent a high-resolution (1.5-mm) CT scan of the temporal
bone prior to treatment. On the basis of the radiographic interpretation,
the maximum extent of disease was felt to be the external auditory canal in
8 (53%) of the 15 patients, the mastoid in 5 (33%), and the middle ear and
otic capsule in 1 patient (7%) each. Ten patients (66%) demonstrated evidence
of bony external auditory canal erosion. Two patients (13%) had clinically
suspicious cervical lymphadenopathy.
The temporal bone CT report was used to determine the preoperative stage
using the University of Pittsburgh staging system for squamous cell carcinoma
of the external auditory canal (Table 2). Final staging was determined by intraoperative findings and the
final surgical pathology report. The preoperative radiographic staging and
the final pathologic staging correlated in 11 (73%) of 15 cases. Radiographic
staging resulted in underestimation of stage in 2 cases and overestimation
of stage in 2 cases (Table 3). Radiographic staging correlated with pathologic staging more often for T3
and T4 tumors than for T1 and T2 tumors (86% vs 63%) (Figure 1). Three patients with T4 disease as diagnosed by CT underwent
contrast-enhanced magnetic resonance imaging (MRI) of the temporal bone. The
MRI findings did not alter the preoperative staging; however, they did offer
additional information on the soft tissue extent of the tumor. The MRI demonstrated
dural enhancement in 2 patients and parotid involvement in 1 patient not visualized
on CT.
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Table 2. Clinical Summary for Patients With Squamous Cell Carcinoma
of the Temporal Bone*
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Table 3. Patients Restaged by Surgical and Final Pathologic Findings
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Axial (A) and coronal (B) computed tomographic scans of the temporal
bone in a patient with squamous cell carcinoma of the left external auditory
canal. The disease was staged as T1 by radiography, but the final surgical
pathologic findings proved it to be T2 with bony erosion.
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All 15 patients underwent surgical resection with curative intent (Table 2). The surgical procedures included
local resections in 3 (20%) of the 15 patients, lateral temporal bone resection
in 8 (53%), and subtotal temporal bone resection in 4 (27%). The facial nerve
was resected in 6 (40%) of 15 procedures in an effort to achieve negative
margins. Eleven patients (73%) received either superficial or total parotidectomy.
Parotid spread was suspected in 1 patient on the basis of preoperative scan
but was found in 2 (18%) of 11 parotid specimens. Modified radical neck dissections
were performed in 6 (40%) cases with 2 (13%) specimens demonstrating lymphatic
spread. Preoperative radiography in both cases of cervical metastasis had
suggested neck disease. In 10 patients (67%), the surgical wound was closed
primarily, 2 (13%) underwent skin grafting, and 3 (20%) required either regional
or distal composite flaps to achieve wound closure. Two of these patients
had a local temporalis muscle flap, while 1 received a latissimus dorsi free
flap.
Surgical complications occurred in 3 patients (20%). One patient had
dehiscence of a regional muscle flap, which healed with local wound care alone.
One patient experienced severe trismus after resection of the mandibular condyle.
Permanent paralysis of the frontal and zygomatic branches of the facial nerve
occurred unexpectedly in 1 patient who had undergone total parotidectomy as
part of the primary resection.
Nine patients (60%) received postoperative radiation therapy, which
was given to patients with large tumors (T3/T4), close (<1 mm) or positive
margins, extensive soft tissue involvement, or regional lymph node involvement.
The mean radiation therapy dose was 6000 rads (60 Gy) to the primary site
and 4500 rads (45 Gy) to the ipsilateral neck.
A multifactorial comparison of potential prognostic factors was performed
on the 13 patients who had either died of disease or had no evidence of disease
after 24 months of follow-up (Table 4). Two patients were excluded from analysis because of insufficient follow-up.
Patient outcome was largely dependent on the extent of the local disease,
which is reflected in the severity of presenting symptoms, the stage of the
primary tumor, and the extent of the surgical resection.
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Table 4. Comparison of Prognostic Factors by Outcome Group*
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COMMENT
Primary squamous cell carcinoma of the temporal bone is an uncommon
malignancy without a universally accepted staging system.2
Arriaga et al3 attempted to address this problem
by introducing the University of Pittsburgh TNM staging system for squamous
cell carcinoma of the external auditory canal in 1990. The staging system
is limited to a single tumor type and anatomic location to avoid the confusion
that arises when tumors of various histopathologic characteristics and locations
are lumped together under a single staging scheme. When clinical outcomes
were compared with histopathologic findings in surgical specimens of 39 patients,
it was found that the extent of local disease closely correlated with patient
outcome. The TNM staging system that emerged from these observations reflects
a 100% 2-year survival for patients with T1 and T2 tumors, 50% in patients
with T3 tumors, and 15% in the T4 group.
The histopathologic-clinical correlation of the University of Pittsburgh
staging system has been supported in recent studies.4-6
In a study of 33 patients with squamous cell carcinoma of the temporal bone,
Zhang et al6 found a 5-year survival of 100%
in the T1/T2 group, a 69% survival in patients with T3 tumors, and 20% survival
in the T4 group. In our study, a group of patients with T1 and T2 tumors had
100% survival during the study period (mean follow-up 54 months), whereas
there was a 25% and 0% survival rate in patients with T3 and T4 tumors, respectively.
The University of Pittsburgh staging system is therefore consistent in its
prediction of survival rate among patients with a similar extent of disease.
An additional strength of the University of Pittsburgh staging system
is its ability to stage disease in patients prior to surgery using preoperative
CT of the temporal bone. High-resolution CT scans of the temporal bone can
readily detect erosion of the bony external canal, which is often the first
sign of local spread of disease.2-3
In a blinded study of 13 patients with squamous cell carcinoma of the external
auditory canal, Arriaga et al3 found that intrepretation
of a preoperative temporal bone CT correlated with surgical histopathologic
findings in 94 of the 96 anatomic sites compared, for an overall accuracy
of 98%. In one case, CT failed to detect the spread of tumor through the anterior
canal wall that occurred without bony erosion. In the other case, mucosal
inflammation of the middle ear was falsely interpreted as tumor. Arriaga et
al3 concluded that preoperative high-resolution
CT scans of the temporal bone accurately reflect the extent of disease and
can therefore be used for preoperative staging and planning for an en bloc resection of the temporal bone. It was also suggested that
MRI may be a helpful adjunct for determining the soft tissue extent of disease.3
The inability of CT scan findings to predict the anterior soft tissue
extent of the tumor has been noted in other studies.7-8
Tumor can spread anteriorly via the cartilaginous fissures of Santorini and
the bony foramen of Huschke without evidence of bony canal erosion.2 Leonetti et al5 reviewed
the accuracy of predicting tumor extent by radiographic means in 17 patients
with T3/T4 squamous cell carcinoma of the temporal bone who had undergone
both CT and MRI scanning. In a site-by-site comparison with intraoperative
findings, CT and MRI had an overall accuracy of 85%. Disease was most frequently
underestimated in the infratemporal fossa, the mastoid cavity, and the carotid
canal.5 Because of concern about anterior spread
of tumor via preformed pathways, Leonetti et al5
routinely perform superficial parotidectomy at the time of temporal bone resection
and total parotidectomy in cases in which the bony canal has been violated.
In the present study, 11 of the 15 patients were correctly staged by
preoperative radiography for an overall staging accuracy of 73%. This percentage
is lower than the previous studies because only the pathologic stage was considered,
and a site-by-site comparison between radiographic interpretation and intraoperative
or histopathologic findings was not undertaken. Using only temporal bone CT,
we underestimated the anterior extent of disease in one case and had difficulty
distinguishing tumor from inflammation in another. The radiographic staging
system seemed to be more accurate for larger (T3/T4) tumors than for smaller
(T1/T2) tumors (83% vs 67%) in which subtle bony changes may be misinterpreted.
En bloc surgical resection of the temporal
bone has remained the preferred treatment for carcinoma of the temporal bone
since subtotal resection was first reported by Parsons and Lewis9
and the laterotemporal bone resection by Conley and Novack.10
Complete tumor resection, the primary aim of these en bloc techniques, is a strong determinant of survival as demonstrated in
our patient series. In the present study, 78% of patients with negative margins
at the time of surgery were disease survivors compared with 0% of patients
with positive margins. Three of our patients with positive margins had dural
involvement that could not be fully resected by a subtotal temporal bone resection.
An additional patient underwent a limited debridement when carcinoma was found
on the carotid artery. When followed by postoperative irradiation, the piecemeal
resection of all visible tumor beyond the margins of a subtotal resection
is a viable alternative to total temporal bone removal and has shown some
benefit in advanced disease.6 Zhang et al6 found 69% and 20% 5-year survival for T3 and T4 disease,
respectively, in patients treated with the piecemeal technique. Total temporal
bone resection with carotid artery sacrifice is not routinely performed at
our institution because of the increased risk of morbidity and no proven survival
benefit. In a meta-analysis of 26 studies of patients with squamous cell carcinoma
of the temporal bone, Prasad and Janecka1 found
0% 1-year survival in 4 patients who had undergone total temporal bone resection.
When specific anatomic sites were considered, patients with dural involvement
had 11% 5-year survival, while those with petrous apex, brain, and carotid
artery involvement had 0% 2-year survival.1
It has also been noted that many patients with squamous cell carcinoma of
the temporal bone are elderly and at risk of dying of intercurrent disease.11
Recent studies, however, have demonstrated improved survival in patients
who have undergone total temporal bone resection.5, 12
In the series by Moffat et al12 7 (47%) of
15 patients with T3/T4 squamous cell carcinoma of the temporal bone survived
5 years following en bloc total temporal bone resection
with carotid artery preservation. Two of the 7 patients had brain involvement
at the time of surgery. Moffat et al12 argue
that improvements in skull base approaches, interventional radiology, and
flap reconstruction have led to improved survival with reduced morbidity.
In addition, they emphasize the palliative benefits of total temporal bone
resection, including decreased pain and improved hygiene.
The conclusions of the present study are limited by the small number
of patients involved. The study findings, however, agree with several recent
studies on the accuracy of the University of Pittsburgh staging system for
squamous cell carcinoma of the temporal bone.6, 13
A multi-institution study is needed to elucidate the optimum treatment for
patients with squamous cell carcinoma of the temporal bone.
CONCLUSIONS
The University of Pittsburgh staging system represents an acceptable
staging system for primary squamous cell carcinoma of the temporal bone, with
excellent correlation between pathologic stage and patient outcome. Although
preoperative radiographic staging is relatively insensitive, the extent of
tumor may be better determined when both CT and MRI of the temporal bone are
performed. The surgeon, however, must be familiar with the common pathways
of tumor spread, which may be missed on preoperative imaging.
AUTHOR INFORMATION
Accepted for publication March 17, 2001.
Presented at the annual meeting of the American Head and Neck Society,
Fifth International Conference on Head and Neck Cancer, San Francisco, Calif,
July 31, 2000.
Corresponding author and reprints: Howard W. Francis, MD, Department
of Otolaryngology–Head and Neck Surgery, The Johns Hopkins University
School of Medicine, 6th Floor JHOC, 601 N Caroline St, Baltimore, MD 21287
(e-mail: hfrancis{at}jhmi.edu).
From the Departments of Otolaryngology–Head and Neck Surgery,
The Medical University of South Carolina, Charleston (Dr Gillespie), and The
Johns Hopkins University School of Medicine, Baltimore, Md (Drs Francis, Chee,
and Eisele).
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