Auris Nasus Larynx 44 (2017) 135–140
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Auris Nasus Larynx
journal homepage: www.elsevier.com/locate/anlStaging and classification criteria for middle ear cholesteatoma
proposed by the Japan Otological Society§Tetsuya Tono a,*, Masafumi Sakagami b, Hiromi Kojima c, Yutaka Yamamoto c,
Keiji Matsuda a, Manabu Komori d, Naohito Hato e, Yuka Morita f, Sho Hashimoto gaDepartment of Otolaryngology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
Department of Otolaryngology, Hyogo College of Medicine, Kobe, Japanc
Department of Otolaryngology, Jikei University School of Medicine, Tokyo, Japand
Department of Otolaryngology, National Center for Child Health and Development, Tokyo, Japane
Department of Otolaryngology, Ehime University School of Medicine, Ehime, Japanf
Department of Otolaryngology, Faculty of Medicine, Niigata University, Niigata, Japang
Department of Otolaryngology, National Sendai Medical Center, Sendai, Japanb

A R T I C L E I N F O

A B S T R A C T

Article history:
Received 27 May 2016
Accepted 28 June 2016
Available online 9 September 2016

In order to provide a basis for meaningful exchange of information among those treating
cholesteatoma, the Committee on Nomenclature of the Japan Otological Society (JOS) was
appointed in 2004 to create a cholesteatoma staging system as simple as possible to use in clinicalpractice in Japan. Following the announcement of preliminary criteria for the staging of parsflaccida (attic) cholesteatoma in 2008, we proposed the 2010 JOS staging system for two major
types of retraction pocket cholesteatoma, pars flaccida and pars tensa cholesteatoma. Since then,the JOS staging system has been widely used in clinical studies of cholesteatoma in Japan, allowing
standardization in reporting of surgical outcomes based on the respective stages of cholesteatoma.
We have recently expanded the range of cholesteatoma by adding cholesteatoma secondary to atensa perforation and congenital cholesteatoma as the 2015 JOS staging system for middle earcholesteatoma. Although further revisions may be required for universal acceptance of thesecriteria, we hope our staging system will open the way for international consensus on staging andclassification of middle ear cholesteatoma in the near future.
ß 2016 Elsevier Ireland Ltd. All rights reserved.

Keywords:
Middle ear cholesteatoma
Classification
Staging

1. Introduction
Middle ear cholesteatoma is characterized by a mass lesion
formed by keratinizing squamous epithelium, keratin debris andvarying thickness of perimatrix, with or without surrounding
inflammatory reaction. Because of the multifactorial and§All authors belong to the Committee on Nomenclature of the Japan
Otological Society (JOS). The criteria set has been approved by the JOS Boardof Directors.
* Corresponding author.
E-mail address: tono@med.miyazaki-u.ac.jp (T. Tono).

http://dx.doi.org/10.1016/j.anl.2016.06.012
0385-8146/ß 2016 Elsevier Ireland Ltd. All rights reserved.

progressive nature of the disease process, pathophysiologicalconditions vary considerably from case to case. Hence, theoperating surgeon is required to make a subjective decision
regarding the most appropriate surgical technique for theindividual situation, to achieve optimal surgical goals,
including disease eradiation and subsequent functional
and anatomical stabilization. Classification and staging ofcholesteatoma would provide a standardized assembly of a
relatively homogenous group of patients, allowing rational
interpretation of surgical results based on respective pathophysiological conditions of the disease process. Needlessto say, proper classification criteria can only be created136

T. Tono et al. / Auris Nasus Larynx 44 (2017) 135–140

by a consensus-based approach, preferably with the supportof an academic society, and should undergo revision overtime.
2. Impact of the previous proposal of criteria(the 2010 JOS staging system) on clinical studies ofcholesteatoma in JapanThe Committee on Nomenclature of the Japan OtologicalSociety (JOS) was appointed in 2004 to create a cholesteatoma
staging system as simple as possible to use in clinical practice,in order to provide a basis for meaningful exchange of
information among those treating cholesteatoma. Althoughseveral criteria for cholesteatoma classification/staging havebeen proposed worldwide [1–5], none of them are simple
enough nor are they authorized by an academic society.
Assuming that the tympanomastoid surgery based on the typeof cholesteatoma has been discussed and cultivated differently
in each country, it was hoped that a consensus-based staging
system primarily for Japanese otolaryngologists could be
developed to start with.
Following the announcement of preliminary criteria forthe staging of pars flaccida (attic) cholesteatoma in 2008 [6],we proposed the 2010 JOS staging system [7] for two major
types of retraction pocket cholesteatoma, pars flaccida andpars tensa cholesteatoma. The basic concept of this system
was twofold: (1) The middle ear space was divided into foursites: protympanum (P), tympanic cavity (T), attic (A) andmastoid (M); (2) Three stages were defined: in stage I, thelesion is confined to the attic or the tympanic cavity; in stage
II, the lesion extends beyond the attic or the tympanic cavity;
in stage III, intratemporal and/or intracranial complications
are observed. Stages II and III can be further sub-classified
according to the extension of the cholesteatoma using the
PTAM system. For example, if the matrix has invaded the
protympanum, the attic and the mastoid antrum withoutcausing any complications, it is described as ‘‘stage II
PAM’’.
Since then, the 2010 JOS staging system has been widelyused in clinical studies of cholesteatoma in Japan, allowing
standardization not only in reporting of surgical outcomes but
also in clinical communications between physicians andpatients based on the respective stage of cholesteatoma. The
number of medical articles referring to the JOS system has
gradually increased in Japanese literature during the past
7 years. A search of the key words of ‘‘cholesteatoma’’ AND‘‘staging’’ in the Japan Medical Abstracts Society web site,
produced 46 original papers and 60 conference abstracts
between 2008 and 2015 [8].
3. Background of the current revision of the previous
criteria
In 2012, we were given the opportunity to present the JOS
staging system during the 9th International Conference oncholesteatoma and ear surgery in Nagasaki, Japan (Chairman of
the meeting, Prof. Haruo Takahashi) [9]. In one of the panel
discussions entitled ‘‘Panel with response analyzer to build up

international consensus on classification and staging of middle
ear cholesteatoma (modulators: Prof. Nuri Ozgirgin and Prof.
Naoaki Yanagihara)’’, this system gained favourable responses
from the international audience as judged by the results of the
response analyzer. However, one point to be considered in orderto make this staging system internationally acceptable was asuggestion to separate the intracranial complications from thestage III elements because intracranial complications are lifethreatening complications which are of great concern
worldwide.
Although the 2010 JOS staging system was designed
exclusively for pars flaccida and pars tensa cholesteatomas,
at least two entities unrelated to a retraction pocket in origin
are fairly well recognized in Japan: cholesteatoma secondary
to a chronic tensa perforation and congenital cholesteatoma.
The former is cholesteatoma that develops secondary to
ingrowth of squamous epithelium through a pre-existingtensa perforation (so-called secondary acquired cholesteatoma). Careful observation using a microscope or an
endoscope is essential to discriminate a continuous epithelial
invasion from the perforation edge to the underside of thepars tensa with no direct adhesive lesion to the promontrial
mucosa [10]. Although a clear distinction between this typeof cholesteatoma and pars tensa cholesteatoma may bedifficult in some cases, the specific staging criteria described
below would help better understanding of the characteristic
process of this disease entity. The latter is congenitalcholesteatoma that develops behind an intact tympanic
membrane. Although academic studies abroad showed thatthe typical location of congenital cholesteatoma is in theanterior superior quadrant of the tympanic cavity [11,12],
this is not necessarily true in Japan, where the posterior
superior quadrant is reportedly the most common site
[13,14]. Therefore, it would be worthwhile to survey clinicaldata of congenital cholesteatoma nationwide using the samestaging criteria, specific for this project.
The current committee to improve the criteria wasconvened under the Japan Otological Society in 2014 toaddress these issues. The original Japanese version has
already been published as the 2015 JOS staging system [15]and its English version is reported here following a publiccomment period of 2 months. The cholesteatoma classification has been slightly modified from the Japanese version
through a collaborative dialogue with members of thecholesteatoma guidelines group of the European Academy of
Otology and Neurotology.
4. Proposed new set of criteria: the 2015 JOS staging
system for middle ear cholesteatoma
4.1. Classification of cholesteatoma
I. Acquired cholesteatoma
1) Retraction pocket cholesteatoma (so-called primaryacquired cholesteatoma)a) Pars flaccida cholesteatoma (Attic cholesteatoma):
Cholesteatoma originating in a pars flaccida retraction pocket.

T. Tono et al. / Auris Nasus Larynx 44 (2017) 135–140b) Pars tensa cholesteatoma: Cholesteatoma originating
in a pars tensa retraction pocket. The range ofretraction varies from a postero-superior quadrant(sinus cholesteatoma) to a partial or an entire parstensa adhesion.
c) Combination of pars flaccida and pars tensacholesteatoma: Cholesteatoma involving both theattic and pars tensa. They may develop as separate
retraction pockets or as an indivisible collapse with
substantial attic and posterior canal wall defects.
2) Nonretraction pocket cholesteatomaa) Cholesteatoma secondary to a chronic tensa perforation (so-called secondary acquired cholesteatoma): Cholesteatoma that develops secondary to
ingrowth of squamous epithelium along the perforation edge to the underside of the pars tensa and themalleus handle without forming a well-defined
retraction pocket.
b) Transplanted cholesteatoma following trauma or
otologic procedures: Cholesteatoma that usuallydevelops as a cyst resulting from the transplantationof squamous epithelial cells into the middle ear
during traumatic or iatrogenic injuries to the
tympanic membrane.
II. Congenital cholesteatoma
Cholesteatoma that develops behind an intact tympanic
membrane. History of otitis media does not necessarily
exclude congenital cholesteatoma but cases having previous otologic procedures should be excluded.
III. Unclassifiable cholesteatoma
Cholesteatoma is not applicable to any of the above
categories. The otoscopic characteristics of cholesteatoma
may be modified if the tympanic membrane undergoes
secondary pathological changes following infections or
otologic procedures.
4.2. Staging of cholesteatoma
4.2.1. Divisions of the middle ear space: PTAM system (Fig. 1)
In order to simplify the extent of cholesteatoma, thetympanomastoid space is divided into four sections: the137

protympanum (P), the tympanic cavity (T), the attic (A) andthe mastoid (M). The protympanum includes the bony
Eustachian tube and the supratubal recess. The tympanic
cavity consists of the mesotympanum, hypotympanum andthe retrotympanum including the tympanic sinus. The
posterior border of the attic is the posterior end of theincus short process or the fossa incudis. The mastoid includes
the antrum and the mastoid cells.
4.2.2. Staging system applicable to the following four types ofcholesteatoma
Stage I: cholesteatoma localized in the primary site**The site of cholesteatoma origin, i.e. the attic (A) for a parsflaccida cholesteatoma and the tympanic cavity (T) for parstensa colesteatoma, congenital cholesteatoma and cholesteatoma secondary to a tensa perforation.
Stage II: Cholesteatoma involving two or more sites
Stage III: Cholesteatoma with extracranial complications
and/or intratemporal pathologic conditions:
Facial palsy (FP), labyrinthine fistula (LF): with conditions
at risk for membranous labyrinth, labyrinthine disturbance(LD): scale out BC values for more than two speechfrequencies (0.5, 1, and 2 kHz), canal wall destruction(CW): more than half the length of the bony ear canal,adhesive otitis (AO): total adhesion of the pars tensa, petrous
bone or skull base destruction (PB), neck abscess (NA).
Stage IV: Cholesteatoma with intracranial complications:
Purulent meningitis, epidural abscess, subdural abscess,brain abscess, sinus thrombosis, etc.

4.3. Staging system for respective cholesteatoma types
4.3.1. Pars flaccida cholesteatoma (attic cholesteatoma)
Stage I: Cholesteatoma localized in the attic
Stage Ia: A retraction pocket with epithelial self-cleaning
function
Stage Ib: A retraction pocket with persistent accumulation of
keratin-debris
Stage II: Cholesteatoma involving two or more sites
Stage III: Cholesteatoma with intratemporal complications
and/or pathologic conditions
Stage IV: Cholesteatoma with intracranial complications

4.3.2. Pars tensa cholesteatoma

Fig. 1. Schematic drawing of divisions of the tympanomastoid space. The
tympanomastoid space is divided into four sections: the protympanum (P), thetympanic cavity (T), the attic (A) and the mastoid (M) in order to represent theextent of cholesteatoma.

Stage I: Cholesteatoma localized in the tympanic cavity
Stage Ia: A retraction pocket with epithelial self-cleaning
function
Stage Ib: A retraction pocket with persistent accumulation of
keratin-debris
Stage II: Cholesteatoma involving two or more sites
Stage III: Cholesteatoma with intratemporal complications
and/or pathologic conditions
Stage IV: Cholesteatoma with intracranial complications

T. Tono et al. / Auris Nasus Larynx 44 (2017) 135–140

138

4.3.3. Cholesteatoma secondary to a tensa perforation
Stage I: Cholesteatoma localized in the tympanic cavity
Stage Ia: Epithelial invasion confined to the underside of thepars tensa
Stage Ib: Epithelial invasion extending to the tensor tympani
tendon and the promontrial wall
Stage II: Cholesteatoma involving two or more sites
Stage III: Cholesteatoma with intratemporal complications
and/or pathologic conditions
Stage IV: Cholesteatoma with intracranial complications

cell development and the pathological status of the stapes.
Both factors are considered to exert characteristic influenceson surgical procedures and long-term outcomes. Computed
tomography (CT), which is a routine preoperative examination before any tympanomastoid surgery in Japan, is used toassess the degree of mastoid cell development. The
pathological status of the stapes can also be judged fromhigh resolution CT but an accurate assessment at surgery isnecessary.
4.4.1. Development of mastoid cells (Fig. 2)

4.3.4. Congenital cholesteatoma
Stage I: Cholesteatoma localized in the tympanic cavity
Stage Ia: Cholesteatoma confined to the anterior half of the
tympanic cavity
Stage Ib: Cholesteatoma confined to the posterior half of the
tympanic cavity
Stage Ic: Cholesteatoma involving both of sides of the
tympanic cavity
Stage II: Cholesteatoma involving two or more sites
Stage III: Cholesteatoma with intratemporal complications
and pathologic conditions
Stage IV: Cholesteatoma with intracranial complications

4.4. Additional criteria for the evaluation of the degree ofmastoid cell development and the pathological status of stapes
Two optional criteria were added to the 2010 JOS system
to meet the demand of JOS members: the degree of mastoid

MC0: almost no cell growth
MC1: cellular structures only around the mastoid antrum
MC2: well developed cellular structures
MC3: cellular structures extending to the peri-labyrinthinearea
The superscript ‘‘a’’ is appended to indicate aeration in
the mastoid (confirmed with preoperative CT or intraoperatively) as‘‘MC2a’’ if the well-developed mastoid cells areaerated.

4.4.2. Pathological status of the stapes (Fig. 3)
S0: no stapes involvement
S1: the superstructure is surrounded by cholesteatoma andgranulation
S2: the superstructure is missing but the footplate remains
intact
S3: the footplate is involved and indistinguishable
SN: the stapes is not observed at surgery.

Fig. 2. Axial CT images representing degrees of mastoid cell development (MC0–3).

T. Tono et al. / Auris Nasus Larynx 44 (2017) 135–140

139

Fig. 3. Schematic drawing of criteria for pathological status of the stapes (S0–S3).

5. Conclusions

Acknowledgements

The 2015 JOS staging system for middle ear cholesteatoma has been developed over the past 7 years through aconsensus-based process and in a step-by-step manner, led by
the Committee on Nomenclature of the JOS. The original
version of the criteria was prepared for pars flaccida
cholesteatoma in 2008. The concept of the criteria fitted
naturally into pars tensa cholesteatoma, leading us to proposethe 2010 JOS staging system as a set of criteria for both typesof retraction pocket cholesteatoma. Successful promotion of
the use of this system has had a significant effect instandardizing reporting of surgical outcomes based on therespective stages of cholesteatoma. We have expanded therange of cholesteatoma by adding cholesteatoma secondary
to a tensa perforation and congenital cholesteatoma as
described in this article. Although further revisions may berequired for universal acceptance of these criteria, we hope
our staging system will open the way for international
consensus on staging and classification of middle earcholesteatoma in the near future.

The authors acknowledge the contribution of JOS members
to the vigorous cultivation of the JOS staging system over the
past 7 years, and the contribution of the members of theCholesteatoma Guidelines Group of EAONO, Nuri Özgirgin,
Ewa Olszewska, Matthew Jung, Armagan Incesulu, Jeff Mulder
and Holger Sudhoff for the collaborative dialogue towards
future consensus between the EAONO and the JOS on thisproject. They would like to thank former committee members,
Makito Okamaoto, Masaru Aoyagi, Tsukasa Ito, Hiroshi Hosoi,
Takashi Nakagawa, Taeko Okuno, Yasuyuki Hinohira andYasuo Mishiro, for their contributions to the development of the2008 and the 2010 versions of the JOS staging system.

Conflict of interest
The authors have no conflict of interest to declare.

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