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A Staging System for Congenital Cholesteatoma
William P. Potsic, MD, MMM;
Daniel S. Samadi, MD;
Roger R. Marsh, PhD;
Ralph F. Wetmore, MD
Arch Otolaryngol Head Neck Surg. 2002;128:1009-1012.
ABSTRACT
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Objective To develop a staging system for congenital cholesteatoma in predicting
the likelihood of residual disease.
Design Retrospective analysis of data from a case series, to identify predictors
of residual disease.
Setting Tertiary care pediatric hospital.
Participants Children undergoing surgical removal of congenital cholesteatoma. There
were 156 patients, with 160 cholesteatomas; 4 children had bilateral disease.
Interventions Each case was scored as to quadrants of the middle ear involved, ossicular
involvement, and mastoid extension.
Main Outcome Measure Surgically confirmed residual disease at any time after the initial
procedure.
Results Four stages were defined as follows: stage I, disease confined to a
single quadrant; stage II, cholesteatoma in multiple quadrants, but without
ossicular involvement or mastoid extension; stage III, ossicular involvement
without mastoid extension; and stage IV, mastoid disease. There was a strong
association between stage and residual disease, ranging from a 13% risk in
stage I to 67% in stage IV.
Conclusions This simple staging system may be particularly useful in standardizing
the reporting of congenital cholesteatoma and in adjusting for severity in
evaluating outcomes. It also provides information that is useful in counseling
parents.
INTRODUCTION
THE CLASSIC presentation of congenital cholesteatoma is as a pearl behind
an intact tympanic membrane in the anterior-superior quadrant, but congenital
cholesteatoma can present elsewhere in the middle ear, can erode ossicles,
and may extend to the mastoid. The extent of disease greatly affects the likelihood
that residual cholesteatoma will remain after surgery. If one is to make comparisons
among practices or to evaluate one's own experience, it is necessary to adjust
for severity of disease. Analyzing the case mix is essential to evaluating
outcomes.
To adjust for severity, it is necessary to evaluate a rather large series
in a consistent fashion, but no one hospital is likely to have enough cases
for this. Recent series typically report that congenital cholesteatomas account
for 10% to 28% of all pediatric cholesteatomas.1-2
As such, they are uncommon enough that few institutions have accumulated experience
with a large series. At the Sixth International Conference on Cholesteatoma
and Ear Surgery,3 8 series of cases were presented.
The median number of cases per report was only 40, and there was no consistency
among authors as to classification systems. Thus, comparisons among series
are difficult, and it is impossible to aggregate all the cases in any meaningful
way.
The solution is to adopt a standard classification system. The value
of such a system for combining data from many centers and risk adjustment
is obvious, but the system would have other value as well. A simple classification
system would be an aid to counseling families, allowing one to explain the
prospects of residual disease in a particular case.
Classification systems for congenital cholesteatoma have been proposed
before. We had previously used a staging system similar but not identical
to the one described herein.1 The previous
system did not adequately differentiate between disease confined to a single
quadrant and more extensive disease, however. Roger et al3
proposed a 4-category system, but it was not exhaustive in that it did not
accommodate all possible cases. Grundfast et al4
described a meticulous reporting system in which presence or absence of disease
is noted for each of 12 sites, but no simple staging system was proposed,
and few others could reconstruct their findings in such detail from existing
records.
METHODS
In a series of chart reviews that extended over 19 years, 160 cases
of congenital cholesteatoma were identified at The Children's Hospital of
Philadelphia, Philadelphia, Pa.1, 5
Approval of the Institutional Review Board at the hospital was obtained for
this retrospective review.
Cholesteatoma was considered to be congenital if the tympanic membrane
was intact and there was no history of otologic surgery (including myringotomy),
otorrhea, or perforation. To rule out previous surgery or perforation, the
hospital's surgical database, as well as office charts (including medical
history) and operative notes, was reviewed. Some early authors considered
any middle ear disease an exclusion criterion,6
but in the present study we used the criteria of Levenson et al,7
who do not exclude cases of otitis media. In addition to history and physical
examination, the findings at surgery were recorded. Presence or absence of
disease was noted for each quadrant of the tympanic membrane at the time of
surgery. Quadrants were defined as follows: The long process of the malleus
was taken as the vertical axis. The horizontal axis was a line perpendicular
to the vertical axis, passing through the umbo. Ossicular involvement was
noted. Cholesteatoma may erode the ossicles or be so adherent to the ossicles
that portions of the ossicular chain must be sacrificed to eradicate disease.
Also, on occasion, removal of ossicles may be required for access to the disease.
It is recognized that the decision to sacrifice ossicles may be subjective,
but this decision does reflect disease severity. For this review, destruction
of any part of the ossicular chain, whether due to disease or surgery, was
classified as ossicular involvement. This category does not include cases
in which cholesteatoma was dissected from the ossicles without compromise
of the ossicular chain. Finally, extension into the mastoid was recorded.
Findings at subsequent surgical procedures were recorded, both for planned
second looks or reconstruction and for surgery required by reappearance of
disease. Any surgically confirmed cholesteatoma behind the tympanic membrane
was presumed to be residual disease, regardless of location or size. Some
authors differentiate between residual and recurrent disease, but it is not
possible to determine whether subsequent disease arose from remnants of the
original cholesteatoma.
Certainly, extent of disease affects audiological findings, but we decided
not to consider the preoperative audiogram as a staging criterion. The reason
is that precise ear-specific thresholds cannot be consistently obtained from
younger patients. Audiometric data from a series that included the present
cases have been analyzed and presented separately.8
Several considerations guided development of the staging system:
- It should be simple. Surgeons are unlikely to complete
a complicated rating system at the time of surgery. Fewer still will have
recorded sufficient detail in their operative notes that fine details could
be reconstructed.
- The classification system should be exclusive:
there should be no ambiguity as to which category to use. It should also be
exhaustive: there should be no cases that cannot be assigned to a category.
- Categories should have good predictive value.
- It is often best to avoid a category that has few
cases, unless membership in that category has special significance. The reason
is that the probability of a particular outcome, such as residual disease,
cannot be estimated precisely with a small sample size.
RESULTS
Eighty-nine percent of the patients in this series were younger than
9 years at the time of surgery (mean age, 4.9 years). There was no significant
left-right difference; 4 patients had bilateral disease. Seventy-one percent
of the patients were male. For this study, follow-up only at our institution
was analyzed. Eighty-four percent of cases were followed up for at least 1
year, and the mean duration of follow-up was 2.7 years. There was a 35% overall
rate of residual disease.
The staging system was developed largely on the basis of clinical experience,
but was modified and refined based on the predictive value of various possible
definitions. As a first step, the predictive value of each dichotomous measure
was determined using a binomial-probability test for significance of the difference
between proportions.9 For example, there was
ossicular involvement in 69 cases, which was associated with a 0.59 chance
of residual disease (Table 1).
In the other 91 cases, there was a 0.16 chance of residual disease. With these
sample sizes, the difference between 0.59 and 0.16 is highly significant (z = 5.64; P<.001). One variable,
the number of quadrants, was not dichotomous. Therefore, dummy variables were
created: more than 1, more than 2, and more than 3. This univariate analysis,
which does not take into account the relationships among variables, showed
that mastoid extension, ossicular involvement, and disease in more than 1
quadrant were all risk factors for residual disease. As for the number of
quadrants, the risk level did not increase greatly if the criterion was more
than 2 or more than 3. For this reason, only the single-multiple dichotomy
was used in further analysis. The presence of disease in any quadrant other
than the anterior-superior quadrant was a predictor of residual cholesteatoma,
but there was a confounding variable: extensive disease was much more common
in these cases.
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Findings at Initial Surgery as Predictors of Residual Disease in 160
Cases
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The next step was to explore combinations of predictors. The best predictor
of good outcome (no residual disease) was disease confined to 1 quadrant of
the middle ear, without ossicular or mastoid involvement. This extent of disease
was defined as stage I. A preliminary version of the classification system
defined stage I as disease limited to the anterior-superior quadrant. In this
series, however, there were 10 cases of single-quadrant disease elsewhere
(9 posterior-superior, 1 posterior-inferior) without ossicular involvement
or mastoid extension. Combining these cases with the anterior-superior cases
increased the predictive power, using P level as
a criterion.
Mastoid extension carried the highest risk of residual disease. Consideration
was given to the predictive value of other factors within this category, to
determine whether mastoid extension should represent the most serious stage,
regardless of other findings. It was found that most of these cases—35
of 39—also had ossicular involvement. Although it was noted that only
1 of the remaining 4 cases had residual disease, the numbers were too small
for meaningful prediction, nor did the number of involved middle ear quadrants
predict which of the mastoid cases would have residual disease. Therefore,
the highest stage, stage IV, included all cases with mastoid extension, regardless
of other findings.
There remained the cases with ossicular involvement, more than 1 quadrant,
or both, but without mastoid extension. Within this group, ossicular involvement
was a strong predictor of severity, regardless of the number of quadrants,
and stage III was defined accordingly. Stage II included all cases with multiple
quadrants but without ossicular or mastoid involvement. Predictive value was
not increased by subdividing stage II according to the number of quadrants.
In summary, the stages are defined as follows:
- Stage I, single quadrant: no ossicular involvement or mastoid
extension.
- Stage II, multiple quadrants: no ossicular involvement or mastoid
extension.
- Stage III, ossicular involvement: includes erosion of ossicles
and surgical removal for eradication of disease; no mastoid extension.
- Stage IV, mastoid extension (regardless of findings elsewhere).
Figure 1 shows the percentage
of cases that fell within each of the 4 stages. Most cases were classified
as stage I, with the remainder rather evenly distributed among stages II,
III, and IV. In Figure 2, it can
be seen that there is a clear association between stage and likelihood of
residual disease, ranging from 13% at stage I to 67% at stage IV.
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Figure 1. Extent of disease. Thirty-nine
percent of ears had cholesteatoma confined to a single quadrant, without ossicular
involvement or mastoid extension. There were fewer cases in each of the other
stages.
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Figure 2. Prediction of residual disease.
Residual cholesteatoma was found in only 13% of stage I cases, but in 67%
of stage IV cases.
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COMMENT
This straightforward classification system is easy to use and has good
predictive value. We have found it to be quite simple to apply and will use
it prospectively as well as for analysis of past cases. Its potential will
not be fully realized, however, unless it is widely accepted and applied to
the reporting of experience from many centers. Will this happen? It is possible
that it will. The great majority of reports of experience with pediatric congenital
cholesteatoma are made by otologists or pediatric otolaryngologists. A good
start would require only the consensus of these 2 groups.
AUTHOR INFORMATION
Accepted for publication February 20, 2002.
This study was presented in part at the 16th Annual Meeting of the American
Society of Pediatric Otolaryngology, Scottsdale, Ariz, May 10, 2001.
Corresponding author: William P. Potsic, MD, MMM, Division of Pediatric
Otolaryngology, 1 Wood Bldg, The Children's Hospital of Philadelphia, 324
S 34th St, Philadelphia, PA 19104 (e-mail: potsic{at}email.chop.edu).
From the Division of Pediatric Otolaryngology, The Children's Hospital
of Philadelphia and University of Pennsylvania School of Medicine.
REFERENCES
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ABSTRACT
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PUBMED
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