Content uploaded by Klaus Earl Loft
Author content
All content in this area was uploaded by Klaus Earl Loft on Dec 27, 2024
Content may be subject to copyright.
https://doi.org/10.1177/1098612X211024498
Journal of Feline Medicine and Surgery
1 –8
© The Author(s) 2021
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/1098612X211024498
journals.sagepub.com/home/jfm
This paper was handled and processed
by the American Editorial Office (AAFP)
for publication in JFMS
Introduction
Cystadenomatosis involves the formation of multiple
cysts originating from the secretory portion of modified
apocrine sweat glands, leading to the development of
characteristic focal to coalescing bluish-black cystic skin
and ear nodules that range from 1 mm to several centi-
meters in diameter (Figure 1). The cysts are often located in
areas of the body where modified apocrine sweat glands
are known to be located.1–6 They have also been reported
to occur in dogs and humans.3,7 Cystadenomatosis has
been found to primarily affect the preauricular region,
concave pinna, concha, tragus and antitragus, and the
external ear canal of cats,8–12 while less commonly affected
areas include the periocular,8,10,13 perioral and perianal
regions (Figure 2).9
The nomenclature for this condition can be confusing,
and terms such as sebaceous or ceruminous cysts,5–7,14,15
Feline cystadenomatosis affecting the
ears and skin of 57 cats (2011–2019)
Klaus E Loft1, Julie Soohoo2, Brooke Simon1
and Christian E Lange3,4
Abstract
Objectives This study aimed to understand epidemiological factors associated with feline cystadenomatosis,
including signalment and papillomavirus PCR status. Cystadenomatosis is an uncommon condition primarily
involving the ceruminous and apocrine skin and ear glands.
Methods This was a retrospective case series. Clinical records from 2011 to 2019 from a tertiary referral hospital in
Boston, MA, USA were screened for cases, and case data were re-evaluated and analyzed. The total patient pool
contained 65,385 individual cats, of which 797 were referred to the dermatology service. Medical records and biopsy
specimens were reviewed; the information collected included signalment, clinical signs, physical examination and
diagnostic tests, comorbidities and histopathologic findings. PCR was performed on biopsy specimens to test for
papillomavirus DNA.
Results The cystadenomatosis population consisted of 57 cases (7.1% of total cases referred to the dermatology
service) with 105 affected ears. Twenty-seven cases (48 ears) were confirmed via histopathology; four cats (7%)
exhibited clinically cystic lesions on the periocular, periorbital and perianal regions; only one cat did not have
pinnal lesions. Domestic shorthair cats were most often affected. Relative risk for cystadenomatosis was 2.24 times
higher in male cats. In 48 cats (84.2%), ears were bilaterally affected. Seven cats (12.3%) had malignant neoplasia,
which included: inflamed adenocarcinoma (n = 5); mast cell tumor (n = 1); or squamous cell carcinoma (n = 1). PCR
testing on biopsy specimens from 24 cats revealed feline papillomavirus type 2 DNA in only four cats.
Conclusions and relevance Cystadenomatosis was more prevalent in senior non-purebred cats, over-represented
in male cats and did not appear to be associated with papillomavirus, feline infectious peritonitis, feline
immunodeficiency virus/feline leukemia virus status or other identifiable illnesses. Further studies are needed to
investigate the causes of cystadenomatosis.
Keywords: Otitis externa; periocular cysts; cysts; cystadenomatosis; apocrine glands; ceruminous glands
Accepted: 23 May 2021
1 Dermatology Service, Angell Animal Medical Center, Boston, MA,
USA
2 VCA Bay Area Veterinary Specialists & Emergency Hospital San
Leandro, CA, USA
3
Department of Immunology, Harvard Medical School, Boston,
MA, USA
4Metabiota Inc, Nanaimo, BC, Canada
Corresponding author:
Klaus E Loft DVM, Dermatology Service, Angell Animal Medical
Center, 350 S Huntington Avenue, Boston, MA 02130, USA
Email: klausloft@gmail.com
1024498JFM Journal of Feline Medicine and SurgeryLoft et al
Original Article
2 Journal of Feline Medicine and Surgery
apocrine cystadenoma, ceruminous cystadenoma,8 apo-
crine cysts, apocrine hidrocystomas,8,13,16 sweat gland
cysts of the skin,5,6,11,12 melanotic ceruminous cysts,17,18
ceruminous gland adenomas, ceruminous gland cysts,19
ceruminous gland hyperplasia,19,20 ceruminous cystoma-
tosis21,22 and epitrichial cystadenomas15 have all been
used. We have previously used the term ‘cystomatosis’
in abstracts.4,23
An adenoma is defined as a benign epithelial neo-
plasm of glandular origin; however, it is non-specific and
hence the microanatomical glandular tissue of origin is
often indicated (ie, apocrine gland) to further specify the
pathology.5,24,25 ‘Cystadenoma’ describes an adenoma in
which the glandular space is cystic.25 According to the
Merriam-Webster medical dictionary,25 the term ‘adeno-
matosis’ is defined as ‘a condition marked by growths
consisting of glandular tissue’. In our view, the term
‘cystadenomatosis’ is a more comprehensive term for the
description of this particular dermatosis. We therefore
propose that the term ‘feline cystadenomatosis’ be used
to describe this clinical syndrome.
Cystadenomatosis has been reported in Europe,7,26
North America,4,21,23 Asia2,27 and South America.16
The clinical sign associated with this benign cutane-
ous neoplasia is minimal inflammation in the sur-
rounding skin.5,6,28,29 However, it can cause obstructive
conformational changes in ear canals and enhance the
likelihood and severity of secondary infectious otitis
externa.11,20,21,30
The glands involved in cystadenomatosis are the modi-
fied sweat apocrine glands, which can be found in the skin
surrounding the eyelid margins (Moll’s glands), lip mar-
gins and perianal regions, but are most prevalent in and
around the ears.5–7,9,13,15,31 The external acoustic meatus of
cats contains ceruminous and sebaceous glands,9,11,12 with
mixed epitrichial and atrichial units,5,6,24,32 which produce
the waxy cerumen emulsion that coats the ear canal sur-
face.12,33 Cerumen is a mixture of desquamated flattened
keratinized squamous epithelial cells and the fatty secre-
tions from sebaceous and ceruminous glands, and helps
to maintain barrier function within the ear canal.1,12,33 In
cats, the ceruminous glands of the external acoustic mea-
tus are folded tubular glands with a wide tubular glandu-
lar architecture and are surrounded by a single or double
layer of myoepithelial cells (Figure 3). The secretory mate-
rial from these modified sweat glands in and around the
ears, eyes and lip margins can be both atrichial (away
from the follicular infundibulum) and epitrichial (termi-
nate in the follicular infundibulum).5,6,24,32
Human and canine ceruminous glands are located in
the deeper layers of the tissue, just beneath the deeper
aspects of the apocrine glands of the ear canal.3,6,7,34 To our
knowledge, this has not been shown in the feline litera-
ture and, according the authors of Skin Diseases of the Dog
and Cat, ‘Interestingly, cysts derived from eccrine sweat
glands have not been observed in dogs or cats’ (p 666).6
The proportion of the ceruminous to sebaceous glands
within the length of the ear canal appears to change as
one moves away from the tympanic membrane.12,35 This
ratio of mainly ceruminous glands is higher in the hori-
zontal meatus compared with the vertical meatus, where
there are more sebaceous and apocrine glands.6,12 The
thin, smooth, epidermally stratified squamous epithelial
Figure 1 Extensive classic bluish-black cystic lesions on the
entire concave pinna and into tragus folds
Figure 2 Open arrows indicate the apocrine cystic lesions
along the eyelids. The solid arrows indicate pre-aural cysts in
an Abyssinian cat. Courtesy of Dr M Coster
Loft et al 3
lining of the external ear canal is histologically similar to
that of the pinna and epidermis;12 however, in most dog
breeds, there are less simple single hair follicles within the
canal, and the hairs do not extend throughout the length
of the canal except in the Cocker Spaniel, which has
more compound hair follicles within the acoustic mea-
tus.2,12,33,36,37 Little has been published regarding this in
cats. According to Fernando’s 1965 paper, secretions from
the cells of the ceruminous glands do not stain histologi-
cally on Mallory’s triple staining, which differs from what
is reported in dogs.2,35 The modified apocrine glands in
cat’s external ears contain acidic mucous substances,
which are found in the apical parts of the glandular cells
and the lumen of these glands, and have properties simi-
lar to mucous glands.2,35The diastase-resistant periodic
acid–Schiff-positive granules of the apocrine glands
found in the external ear canal are located near the apical
borders of the glandular cells in cats.2,35
The bluish-black clinical appearance of the cystad-
enomatosis lesions are partially a reflection of the dis-
tended skin and partially attributed to the pigmentary
contributions from hemosiderin and ceroid of the thick
acellular or cell-poor fluid filling the cystic lumen.5,12,15
Histopathologically, these cysts have been theorized to
be caused by obstructed glandular ducts,13,16 or retention
cysts, based on the flattened appearance of epithelial cells
with dermal fibrosis or due to compression exerted from
benign adenomas process with papillary digital projec-
tions into the cystic cavities.15 No known etiology has
been identified as a potential cause for the cyst formation,
but some authors have theorized that a senile change may
play a role in cyst formation.5,6
Feline cystadenomatosis has been reported in the
literature to be a rare benign neoplasia, and has been
observed to occur most commonly in middle-aged to
older Abyssinian, Himalayan and Persian cats.6,9,12,13,15,24
Therapeutic approaches ranging from benign neglect to
various topical and systemic anti-inflammatory treat-
ments to draining of the cysts to chemical ablation,14,15,21
cauterization, cryosurgery,27,33 surgical excision15,31 or
laser surgery4,19,38 have been suggested; however, con-
tinued development of new lesions after removal is
common.4,15,21
In order to better understand this clinical syndrome,
a retrospective study was conducted to investigate any
potential association between cystadenomatosis and fac-
tors such as age, sex, breed, feline immunodeficiency
virus (FIV)/feline leukemia virus (FeLV) status and
comorbidities. We also decided to screen for the pres-
ence of papillomavirus (PV) DNA in tissue collected
from 24/44 cystadenomatosis cases, as PV is known to be
associated with the development of several types of cuta-
neous neoplasms.39–41 Only cases that were examined
and sampled in the period 2011–2015 were tested for PV.
Materials and methods
The medical records of 797 individual feline patients,
seen by the dermatology service at Angell Animal
Medical Center in Boston, MA, USA from January 2011
to December 2019 exclusively, were reviewed.
Signalment information and other data were included
in the study and reviewed. To determine prevalence, the
number of cases consistent with a clinical diagnosis of
cystadenomatosis was compared with the total referred
feline population seen by the dermatology service during
the same 84 months. The medical records of all patients
were reviewed. We used the first mention of otitis externa
or lesions consistent with a likely diagnosis of cystadeno-
matosis. The identification of cysts in medical records
was used as the best estimate for age of onset of cysta-
denomatosis in a given patient. Where such information
was missing from the records, we used the date of first
presentation to the dermatology service for referral as the
age of onset. Data regarding sex, breed (when provided
by owner) and FIV/FeLV status (when available) were
collected. The histopathologic findings from 27 cats (if
applicable; see Figure 3) and concurrent medical condi-
tions were also collected.
Biopsy specimens from 24 of these animals were sub-
mitted for PCR testing to evaluate for the presence of
PV. Either fresh frozen or paraffin-embedded tissue was
used, and DNA was extracted with a DNeasy extraction
kit (Qiagen) according to the manufacturer’s recommen-
dations. In order to detect PV DNA in the extracts, six
different PCR assays were employed. Two of the PCRs
used degenerate primers for conserved regions to detect
a broad spectrum of PV types, with the FAP59/FAP64
assay targeting the L1 gene and the CP4/CP5 assay tar-
geting the E1 gene.39,41 Additionally, four PCRs were used
to test specifically for feline PV2 (FcaPV) types 1–4. For
FcaPV2, the JMPF/JMPR primers were selected, while
Figure 3 Histopathology from a cystadenomatosis-affected
ear. Courtesy of Dr P Mouser
4 Journal of Feline Medicine and Surgery
new primers were designed for FcaPV1, FcaPV3 and
FcaPV4: FcaPV1_L1 f (5’-TTG GGA GAG GAC AAC CTT
TG-3’)/FcaPV1_L1 r (5’-GGC TTA CAG CCC ACC ATA
AA-3’), FcaPV3_L1 f (5’-GTT TGC TTT GGC AGA CCC
TA-3’)/FcaPV3_L1 r (5’-TGG ACA CAT TTT GCC TTT
CA-3’) and FcaPV4_L1 f (5’-TGG TGA TGA AAG GCA
AAA CA-3’)/FcaPV4_L1 r (5’-CAA AGC CCA CAT CAC
ACA TC-3’), respectively.42 The FAP59/FAP64, CP4/CP5
and JMPF/JMPR PCRs were performed as previously
published,39,41,42,43 while for the other three PCR assays
an initial denaturation of 94°C for 3 mins was used, fol-
lowed by 40 cycles of 94°C for 30 s, 55°C for 30 s and 72°C
for 30 s. PCR products were loaded and visualized on
an agarose gel, amplicons were cut out and DNA was
purified using a QIAquick DNA extraction kit (Qiagen).
Sequencing was performed in an ABI 3730 sequencer
(Applied Biosystems), and the results were compared
with the National Center for Biotechnology Information
(NCBI) database using the BLAST N algorithm. The PCR
protocols were performed as published and, in the case
of the novel PCR assays, an initial denaturation of 94°C
for 3 mins was used, followed by 40 cycles of 94°C for
30 s, 55°C for 30 s and 72°C for 30 s. PCR products were
loaded and visualized on an agarose gel, amplicons were
cut out and DNA was purified using a QIAquick DNA
extraction kit (Qiagen). Sequencing was performed in an
ABI 3730 sequencer (Applied Biosystems), and the results
were compared with the NCBI database using the BLAST
N algorithm.
Statistical analysis
Descriptive data were generated using www.medcalc.org
and Microsoft Excel; comparison of means and a χ2 test of
independence were performed.
Results
Cystadenomatosis was found in 7.1% (n = 57/797) of
referrals and in 0.1% of the total hospital feline popu-
lation seen (n = 57/65,385) during the study period. Of
the 57 cats that had lesions consistent with cystadeno-
matosis, 84.2% (n = 48/57) had both ears affected, and in
4/57 cats (7.0%), clinically similar cystic lesions were also
noted in other locations on the body (one in the periocu-
lar region, two in the periorbital region and one in the
perianal region). In 27 cats (48 ears) (47.4%, n = 27/57),
the diagnosis of cystadenomatosis was confirmed his-
topathologically and PCR testing for the presence of PV
was conducted on biopsy material from 24 of these cats.
FcaPV2 DNA was detected in 4/24 (16.7%) cats.
The mean ± SD age of onset among affected cats was
11 ± 3.0 years (range 3.5–17). The mean ± SD age of unaf-
fected cats seen by the dermatology service (n = 740) at
the time of referral was 7.31 ± 4.37 years (range 0.5–19.2)
(P <0.0001). Domestic shorthair cats were most com-
monly affected (57.9%, n = 33/57). Other breeds included
Table 1 Distribution of breeds seen by the dermatology
service, 2011–2019
Breed as reported
by owner
Referred patients
(n = 797)
Cystadenomatosis
cases (n = 57)
Abyssinian 5 1
DLH 87 7
DMH 71 13
DSH 491 33
Himalayan 8 2
Persian 13 1
25 other breeds
(at least one cat)
122 0
DLH = domestic longhair; DMH = domestic mediumhair;
DSH = domestic shor thair
Table 2 Sex distribution of all cats (n = 797) seen by the
dermatology service, 2011–2019
Sex Non-affected
(n = 740)
Affected
(n = 57)
Male intact 12 2
Male castrated 375 40
Female intact 9 1
Female spayed 401 14
domestic mediumhair (n = 13 [22.8%]), domestic long-
hair (n = 7 [14%]), Persian (n = 2 [3.5%]), Himalayan
(n = 1 [1.8%]) and Abyssinian (n = 1 [1.8%]) (Table 1).
There was no significant breed predisposition in the
overall population of cats referred to the dermatology
service (χ2 [degrees of freedom 6, n = 797] = 0.786275,
P = 0.992439, P <0.05).
Cystadenomatosis was found in one intact female
(1.8%), 14 spayed females (24.6%), two intact males (3.5 %)
and 40 castrated males (70.2%). Most of the cats in both the
affected and the total referred populations were spayed
or castrated (n = 54/57 [94.7%] and n = 776/797 [97.4%],
respectively) (Table 2). Of the 57 affected cats, there was
a male:female ratio of 2.8. The male (intact plus castrated,
n = 387) to female (intact and spayed, n = 410) ratio in the
referral population was 0.94. The male cats had a 2.24
higher relative risk of developing cystadenomatosis than
female cats (99% confidence interval 1.27–1.809).
Seven of the 57 cases (12.3%) were diagnosed with
malignant neoplasia in and around the ears and included
the following diagnoses: inflamed adenocarcinoma
(n = 5); mast cell tumor on pinna (n = 1); and squamous
cell carcinoma (n = 1). A range of concurrent clinical con-
ditions was reported in the 57 affected cats, with a range
of clinical signs and/or a medical history of dermato-
logic problems and treatments suggestive of some form
of allergic dermatosis (n = 3); chronic renal failure (n = 2);
Loft et al 5
pancreatitis (n = 1); chylothorax (n = 1); diabetes mellitus
(n = 1); hyperthyroidism (n = 2); atopic dermatitis (n = 1);
and lymphoma (n = 1). However, the majority of cases
(n = 48) had no known clinical disease requiring medi-
cal attention besides secondary otitis externa (bacterial,
yeast or mixed) owing to cystadenomatosis. No cats in
the study had required treatment for an ear infection
prior to developing cysts, other than a single cat that had
a history of ear mites (Otodectes species). A review of the
medical records showed that in 42 of the cases of cystad-
enomatosis, there had been clinical signs consistent with
secondary otitis externa unilaterally or bilaterally upon
or within the 6 months prior to referral.
Medical management of clinical signs in these 42 cats
ranged from maintenance cleaning with various clean-
ing solutions to prescription otic topical medications for
inflammatory and/or infectious otitis signs. No obvious
pattern was seen, and comparison of effect was not per-
formed on the different treatments, since patients were
presented at various times during their treatment and
disease progression.
Four cats (seven ears) needed to undergo total ear
canal ablation and bulla osteotomy (TECABO) owing to
progression of the cystadenomatosis and/or complica-
tions from chronic otitis externa and/or neoplasia in or
around the ears. Two of the cats that underwent TECABO
had initially had their diagnosis confirmed via histopa-
thology, and had failed to resolve with CO2 laser therapy
prior to needing more extensive surgery. A single case
had a unilateral TECABO and two had pinnectomy per-
formed prior to referral owing to a diagnosis of suspected
cystadenomatosis.
The FIV/FeLV status of 5/57 cats was unknown.
Fifty-one cats were either listed as negative for FIV and
FeLV by owners, or as current or up to date with vac-
cine protection for FeLV. One cat was FIV-positive and
was euthanized due to a brain tumor. One cat was con-
sidered positive for feline infectious peritonitis (FIP) but
remained non-clinical for FIP. None of the other cats with
unknown FIV/FeLV status had malignant neoplasia in
the ears. Only three (5.3%) of the 57 cats with cystad-
enomatosis had signs and/or medical history of der-
matologic problems and treatments suggestive of some
form of allergic dermatosis, prior to developing clinical
cystadenomatosis.
Discussion
In this retrospective study from a referral tertiary ani-
mal hospital population, we found that feline cysta-
denomatosis was not associated with certain breeds
such as Persians or Himalayans, as previously sugges-
ted,13,15,16,21,27,32,44 although in a 2005 textbook one author
noted that DSH cats were the most affected breed.6 In
this study, cystadenomatosis was over-represented in
non-purebred cats, though the association was not sta-
tistically significant. In the present study, male cats were
1.52 times more likely to develop ceruminous cysts than
female cats, and affected male cats were more likely to
be castrated than intact, consistent with previous stud-
ies and publications.7,22,44 This raises the question of
whether male sex hormones could potentially affect
glandular tissue and play some role in its progres-
sion into a cystic pathology, even with the majority of
patients being spayed or castrated. Similar to previous
studies, the condition appears to occur in cats as young
as 3.5 years of age but more commonly affects older cats,
as in our study population (mean of 11 years).7,15,24,44
Most cats had bilateral disease, with or without
lesions associated with the ears (n = 4/57). The perio-
cular zone appears to be the second most common area
to develop cystic lesions (n = 2/57), which is consistent
with the ophthalmology literature.13,16,27 The condition
has been recognized in almost all regions of the world
short of Oceania and Africa. In our view, this is more
likely to be due to a lack of publications on the topic,
rather a true reflection of the prevalence of disease. The
most common clinical presentation beside cysts was
the owner experiencing increasing difficulty with the
management of secondary bacterial and/or Malassezia
otitis externa. This was likely due to growth of the cystic
lesions in the tragus and meatic entrance, making topi-
cal treatments more difficult for owners.4,15,21,41
CO2 laser surgery using a model LX-20SP (www.aes
culight.com) was carried out by two of the authors (KEL
and BS) on a total of 34 ears and in three non-ear loca-
tions (chin, lip, perianal area) in 23 patients (three cats
had TECABO or pinnectomy prior to referral). In this
study, we found that CO2 laser surgery was, subjec-
tively, a good treatment option for patients where cysts
had reached a size or distribution that caused increased
risk of otitis externa owing to the obstructive nature of
the lesions, patient discomfort or increased difficulty
in resolving secondary infections. Post-laser complica-
tions were short term and only three cats required 14
days of treatment. Regarding secondary infections, the
most common clinical post-procedural observation by
owners and clinicians was, surprisingly, minimal local
discomfort for a few days after the procedure (Figure
4). However, a limitation of CO2 laser therapy is that it
is unable to treat cysts that extend deep into the hori-
zontal canal without causing damage to unaffected tis-
sues. Diode laser and holmium type lasers will likely
be advantageous in these cases, but the cost might be
a limiting factor. We have carried out ‘touch-up’ treat-
ment on four severely affected cases over the span of
the study, mainly when the cats where under general
anesthesia for other reasons such as for dental cleaning.
In two cats with malignant ear tumors, we performed
a second round of CO2 laser treatment in an attempt
to give those cats additional quality of life and allow-
ing for topical palliative care, without resolving the
malignancy.
6 Journal of Feline Medicine and Surgery
The nine cats with concurrent non-cystadenoma medi-
cal conditions were considered to be within the normal
occurrence in a population of senior cats, and we could
not establish any pattern between their conditions and
cystadenomatosis. No association with PV infection
was found with the PCR testing carried out in 24 cases.
Although FcaPV2, in particular, has been found to be
causally involved in the etiology of certain human and
feline cutaneous tumors,39,40,45,46 the virus may also be
found in or on the skin of cats without any associated
clinical signs.43 The detection of FcaPV2 DNA in 4/24
tested cats indicates no connection between cystomatosis
and PV infection. We also did not establish any associa-
tion between FIV/FeLV or FIP and cystadenomatosis in
our population. In a previous study, 1/4 cats with benign
ear tumors tested positive for FeLV and two and one of 56
cats with malignant ear tumors were FeLV positive and
FIV positive, respectively.
Based on the documented communication with the cli-
ent or owner, the cats in our study did not have a history
of aural clinical signs prior to the cysts being noted by the
owners and/or veterinarians. Only one of the affected cats
was confirmed to have had ear mites (Otodectes cynotis)
prior to the development of cystadenomatosis. However,
the lack of previous history of otitis externa suggests
that cystadenomatosis does not appear to be a reactive
hyperplastic change for the majority of cases or appear
to be over-represented among allergic or hypersensitive
cats since only 3/57 had signs of allergic skin disease.
Furthermore, the prevalence of ear mite infestations is
highest in young individuals owing to transmission from
the queen to the kitten.15,20,47,48 However, feline cystadeno-
matosis is more commonly found in cats that are middle-
aged and older and could support a possible senile or
degenerative change in the tissue or its associated struc-
tures, and be less supportive of a congenital etiology.22
The finding of neoplastic conditions in 17% of the cases
is in line with what has previously been reported in the
literature, where the mean age of onset for malignant
ear tumors (such as ceruminous adenocarcinoma and
squamous cell carcinoma) is 11 years.7,12,15,44 In the pre-
sent study, there was no significant association between
cystadenomatosis and malignant ear neoplasia.
Conclusions
Further investigation into the pathology of adenoma
formation, and particularly into the feline apocrine and
ceruminous glands, will be needed to identify specific
etiologic factors and subsequent potential effective strat-
egies for reducing the complications associated with
cystadenomatosis.
In our experience, CO2 laser therapy appears to be
a useful approach for ablating cysts in more mild cases
and minimizing the risk of obstruction in more severe
cases.19,21,38
It is possible that a similar effect could be achieved
with cryotherapy and/or electrocautery, but we have had
less success with this approach. In cases with moderate
obstructive changes of the upper sections of the acoustic
meatus, the reconstructive surgery proposed by Pavletic31
could be a viable consideration.
Acknowledgements We would like to thanks Drs Coster,
Ewing and Mouser (all from Angell AMC, Boston, MA, USA)
for their generous help in reviewing sections of the article, as
well as gathering images of feline patients and in providing
photomicrographs of the tissue.
Author note This study was presented, in part, at the North
American Veterinary Dermatology Forum (NAVDF) 2014 in
Phoenix, AZ, USA, and the NAVDF 2017 in Orlando, FL, USA.
These two initial presentations was approved by the Angell
Institutional Research Board.
Conict of interest The authors declared no potential
conflicts of interest with respect to the research, authorship,
and/or publication of this article.
Funding This study was self-funded.
Ethical approval This work involved the use of non-
experimental animals only (including owned or unowned
animals and data from prospective or retrospective studies).
Established internationally recognized high standards (‘best
practice’) of individual veterinary clinical patient care were
followed. Ethical approval from a committee was therefore not
specifically required for publication in JFMS.
Informed consent Informed consent (either verbal or writ-
ten) was obtained from the owner or legal custodian of all
animal(s) described in this work (either experimental or non-
experimental animals) for the procedure(s) undertaken (either
prospective or retrospective studies). No animals or humans
Figure 4 Post CO2 laser of same cat as in Figure 1. Courtesy
of Dr P Mouser
Loft et al 7
are identifiable within this publication, and therefore addi-
tional informed consent for publication was not required.
ORCID iD Klaus E Loft https://orcid.org/0000-0002-
5863-3631
References
1 Cole LK. Anatomy and physiology of the canine ear. Vet
Dermatol 2009; 20: 412–421.
2 Fernado L. Microscopic anatomy and histochemistry of
glands in the external auditory meatus of the cat (Felis
domesticus). Am J Vet Res 1965; 26: 1157–1162.
3 Freinkel RK, Woodley DT, Haake A, etal. The biology of
the skin. Boca Raton, FL: CRC Press, 2001.
4 Soohoo J, Lange CE and Loft KE. Feline ceruminous cysto-
matosis in the ears of 25 cats (2014–2016). Abstracts of the
North American Veterinary Dermatology Forum 26–29
April 2017 Orlando, FL, USA. Vet Dermatol 2017; 28: 426–455.
5 Gross T, Ihrke PJ and Walder EJ. Sweat gland tumors. In:
Gross T, Ihrke PJ and Walder EJ (eds). Veterinary derma-
topathology: a macroscopic and microscopic evaluation of
canine and feline skin disease. St Louis, MO: Mosby, 1992,
pp 386–392.
6 Gross T, Ihrke PJ and Walder EJ. Sweat gland tumors. In:
Gross T, Ihrke PJ and Walder EJ (eds). Skin diseases of the
dog and cat: clinical and histopathologic diagnosis. Oxford:
Blackwell Publishing, 2005, p 668.
7 van der Gaag I. The pathology of the external ear canal in
dogs and cats. Vet Q 1986; 8: 307–317.
8 Esson D. Apocrine hidrocystoma. In: Esson D (ed). Clini-
cal atlas of canine and feline ophthalmic disease. Ames, IA:
Wiley Blackwell, 2015, pp 58–59.
9 Chaitman J, Van Der Woerdt A and Bartick TE. Multiple eye-
lid cysts resembling apocrine hidrocystomas in three Per-
sian cats and one Himalayan cat. Vet Pathol 1999; 36: 474–476.
10 Kahane N, Ofri R, Prager O, etal. Apocrine hidrocystoma
in four Persian cats. Isr J Vet Med 2014; 69: 29–34.
11 Gotthelf L. Factors that predispose in the ear to otitis
externa. In: Gotthelf L (ed). Small animal ear diseases, an
illustrated guide. St Louis, MO: Saunders, 2001, pp 61–63.
12 Gotthelf L. Small animal ear diseases, an illustrated guide.
St Louis, MO: Saunders Elsevier, 2005.
13 Newkirk KM and Rohrbach BW. A retrospective study of
eyelid tumors from 43 cats. Vet Pathol 2009; 46: 916–927.
14 Campbell K. Non-neoplastic tumors. In: Campbell K (ed).
Secrets of dermatology. Philadelpha, PA: Hanley & Belfus,
2004, pp 386–410.
15 Miller W, Griffin C and Campbell K. Diseases of eyelids,
claws, anal sacs and ears. In: Miller W, Griffin C and Camp-
bell K (eds). Muller and Kirk’s small animal dermatology.
St Louis, MO: Elsevier, 2012, pp 724–773.
16 Brasil Tadeu Pigatto S, Antonio J, Albuquerque D, etal. Eye-
lid apocrine hidrocystomas in a cat. Acta Sci Vet 2016; 44: 1–4.
17 Harvey RG, Harari J and Delauche A. Etiopathogenesis
and classification of otitis externa. In: Harvey RG, Harari J
and Delauche A (eds). Ear disease of the dog and cat. Iowa
City, IA: Iowa State University Press, 2001, pp 107–108.
18 Harvey RG and ter Haar G. Anatomy and physiology of
the ear. In: Harvey RG and ter Haar G (eds). Ear, nose and
throat diseases of the dog and cat. Boca Raton, FL: CRC
Press, 2016, p 506.
19 Corriveau LA. Use of a carbon dioxide laser to treat ceru-
minous gland hyperplasia in a cat. J Feline Med Surg 2012;
14: 413–416.
20 Kennis RA. Feline otitis. Diagnosis and treatment. Vet Clin
North Am Small Anim Pract 2013; 43: 51–56.
21 Berger D. Feline ceruminous cystomatosis. Clin Brief 2015; 42.
22 Sula MJM. Tumors and tumorlike lesions of dog and
cat ears. Vet Clin North Am Small Anim Pract 2012; 42:
1161–1178.
23 Loft KE. Apocrine cysts in cat ears (cystomatosis): 12 cases
(2011–2013). Vet Dermatol 2014; 25: 145–162.
24 Moulton J. Tumor of domestic animals. In: Moulton J (ed).
Tumors in domestic animals. Ames, IA: Iowa State Press,
1990, pp 66–70.
25 Merriam-Webster. Merriam-Webster’s medical desk diction-
ary. Clifton Park, NY: CENGAGE Delmar Learning, 2005.
26 Topala˘ R, Burtan I, Fântânaru M, et al. Epidemiological
studies of otitis externa at carnivores. Lucr S¸tiinłifice Med
Vet 2007; XL: 647–651.
27 Yang S-H, Liu C-H, Hsu C-D, etal. Use of chemical ablation
with trichloroacetic acid to treat eyelid apocrine hidrocys-
tomas in a cat. J Am Vet Med Assoc 2007; 230: 1170–1173.
28 Kaddu S and Kerl H. Appendage tumors of the skin. In:
Freedberg IM, Eisen AZ, Wolff K, etal (eds). Fitzpatrick’s
dermatology in general medicine. New York: McGraw-Hill
Professional Publishing, 2003, pp 784–795.
29 Kiupel M, Capen C, Miller M, et al. Histological classi-
fication of tumors of the endocrine system of domestic
animals. In: Armed Forces Institute of Pathology (eds). Inter-
national histological classification of tumors of domestic
animals: second series. Washington, DC: Armed Forces Insti-
tute of Pathology, 1994.
30 London CA and Dubilzeig RR. Evaluation of dogs and cats
with tumors of the ear canal 145 cases (1978–1992). J Am
Vet Med Assoc 1996; 208: 1413–1418.
31 Pavletic MM. Partial vertical ear canal resection in two
cats. J Am Vet Med Assoc 2019; 255: 1365–1368.
32 Shofer FS and Goldschmidt M. Apocrine gland tumors. In:
Shofer FS and Goldschmidt M (eds). Skin tumors in cats
and dogs. Oxford: Pergamon Press, 1992, pp 84–89.
33 Njaa BL, Cole LK and Tabacca N. Practical otic anatomy
and physiology of the dog and cat. Vet Clin North Am Small
Anim Pract 2012; 42: 1109–1126.
34 McCalmont TC. Adnexal Neoplasms. In: Bolognia JL,
Jorizzo JL and Schaffer JV (eds). Dermatology 3rd ed. St
Louis, MO: Elsevier Inc, 2008, pp 1817–1844.
35 Özcan Z. Some histochemical properties of the cerumi-
nous glands in the meatus acusticus externus in cats and
dogs. Turkish J Vet Anim Sci 2005; 29: 917–921.
36 Njaa BL and Sula MJM. Collection and preparation of dog
and cat ears for histologic examination. Vet Clin North Am
Small Anim Pract 2012; 42: 1127–1135.
37 Vogelnest L. Comparative gross and microscopic anatomy
of the external, middle, and inner in health: dogs. Austra-
lian and New Zealand College of Veterinary Scientist, Dermatol-
ogy Chapter 2015; 3: 54–67.
38 Duclos D. Lasers in veterinary dermatology. Vet Clin North
Am Small Anim Pract 2006; 36: 15–37.
8 Journal of Feline Medicine and Surgery
39 Forslund O, Antonsson A, Nordin P, etal. A broad range of
human papillomavirus types detected with a general PCR
method suitable for analysis of cutaneous tumours and
normal skin. J Gen Virol 1999; 80: 2437–2443.
40 Munday JS, Kiupel M, French AF, etal. Detection of papil-
lomaviral sequences in feline Bowenoid in situ carcinoma
using consensus primers. Vet Dermatol 2007; 18: 241–245.
41 Iftner A, Klug SJ, Garbe C, etal. The prevalence of human
papillomavirus genotypes in nonmelanoma skin cancers
of nonimmunosuppressed individuals identifies high-
risk genital types as possible risk factors. Cancer Res 2003;
63: 7515–7519.
42 Munday JS, Kiupel M, French AF, etal. Amplification of
papillomaviral DNA sequences from a high proportion
of feline cutaneous in situ and invasive squamous cell
carcinomas using a nested polymerase chain reaction. Vet
Dermatol 2008; 19: 259–263.
43 Geisseler M, Lange CE, Favrot C, et al. Geno- and sero-
prevalence of Felis domesticus Papillomavirus type 2
(FdPV2) in dermatologically healthy cats. BMC Vet Res
2016; 12: 147. DOI: 10.1186/s12917-016-0776-7.
44 Miller MA, Nelson SL, Turk JR, etal. Cutaneous neoplasia
in 340 cats. Vet Pathol 1991; 28: 389–395.
45 Munday JS, Thomson NA, Henderson G, etal. Identifica-
tion of Felis catus papillomavirus 3 in skin neoplasms
from four cats. J Vet Diagn Invest 2018; 30: 324–328.
46 Munday JS, Thomson NA and Luff JA. Papillomaviruses
in dogs and cats. Vet J 2017; 225: 23–31.
47 Bowman DD. Arthropods. In: Bowman DD (ed) Georgis’
parasitology for veterinarians. St Louis, MO: Elsevier, 2003,
pp 5–83.
48 Lynn RC. Antiparasitic drugs. In: Bowman DD (ed) Geor-
gis’ parasitology for veterinarians. St Louis, MO: Elsevier,
2003, pp 254–294.
