Journal of Feline Medicine and Surgery (2009) 11, 487e491doi:10.1016/j.jfms.2008.11.006

Eyelid multiple cysts of the apocrine gland ofMoll in Persian cats

Chiara Giudice DVM, PhD1*, Maria C Muscolo DVM

2, Marco Rondena DVM, PhD1,

Alberto Crotti DVM3, Valeria Grieco DVM, PhD

1

1Section of Veterinary Pathology,Department of VeterinaryPathology, Hygiene and PublicHealth, University of Milan, viaCeloria 10, 20133 Milan, Italy2Clinica Veterinaria Basiglio, p.zaMonsignor Rossi 14, 20080Basiglio, Milan, Italy3via P. Revelli Beaumont 43,16143 Genova, Italy

*Corresponding author. E-mail: chiara.g

1098-612X/09/060487+05 $34.00/0

Feline eyelid hidrocystoma is a rarely reported disease of the apocrine glands ofMoll that has been variably interpreted as proliferative/neoplastic lesion orretention cyst. The purpose of this paper was to investigate feline hidrocystomapathogenesis by means of a histological and immunohistochemical study.Nine paraffin embedded biopsies of eyelid hidrocystoma were retrieved fromour archives. Histological sections were immunostained with antibodiesanti-cytoskeletal proteins and Ki67 antigen. All hidrocystomas were observedin Persian cats, seven males/two females, mean age 9.6 years. Histologically,single or multiple, variably sized cysts expanded eyelid dermis. Cyst was linedby cuboidal epithelium, occasionally raising in papillary structures.Immunostaining was consistent with apocrine gland epithelium (cytokeratin 8/18;19 and 14 positive). Ki67 immunolabelled nuclei ranged from 5.3 to 20.83%.Although it was not possible to draw a definite conclusion concerninghidrocystoma aetiopathogenesis, the relatively high Ki67-proliferative indexobserved, suggested a proliferative nature of the lesion.

Date accepted: 1 November 2008 � 2008 ESFM and AAFP. Published by Elsevier Ltd. All rights reserved.

Moll’s glands are modified sweat glandslocated at the margin of the eyelids andin the overlying epidermis of the lid.1,2

The structure and location of the glands of Moll aresimilar in all domestic species.1 The histologicalfeatures of Moll’s glands are consistent with apocrineglands, however, their function is still unknown bothin humans and in animals.1,2 The presence of a varietyof antimicrobial proteins (eg, lysozyme, b-defensin-2,adrenomedullin, lactoferrin, and IgA) in Moll’s glandsecretions in primates has suggested their contribu-tion in ocular host defence.2 Similar studies have notbeen performed in domestic species.

Single or multiple benign cystic lesions of the eye-lid, originating from the glands of Moll are referred,in man, as apocrine hidrocystoma.3,4 The aetiopatho-genesis of apocrine hidrocystoma is currently un-known and the lesion has been variably interpretedeither as proliferative adenomatous tumour5e7 or asretention cyst caused by excretory duct obstruction.8

The veterinary literature reports only a few casesof multiple eyelid cystic lesions/hidrocystomasin cats.9e12 Most eyelid hidrocystomas have been re-ported in Persian cats, suggesting a possible breed

iudice@unimi.it

� 2008 ESFM a

predisposition.10 In most of reported cases, whenfollow-up data were available, additional cysts devel-oped 11 months to 5 years after surgical removal.

The aim of our study was to contribute to a betterunderstanding of the pathogenesis and the histologi-cal characterisation of eyelid apocrine hidrocystoma.To the authors’ best knowledge this study presentsthe largest collection of feline eyelid hidrocystomasreported so far.

Materials and methodsParaffin embedded excisional biopsies of feline eye-lids with a histopathological diagnosis of apocrinecystic lesion were retrieved from the archive of the Di-vision of Veterinary Pathology (2003e2007). Clinicalrecords and histological slides were reviewed. Ninecases of lesions consistent with a histological diagno-sis of hidrocystoma were selected.

Data concerning clinical presentation and follow-upwere obtained, for these nine cases, by contactingreferring ophthalmologists.

Five microns serial sections were obtained fromparaffin blocks, and stained with haematoxylin andeosin (HE) and Mallory. Additional serial sectionswere obtained from 8/9 specimens and

nd AAFP. Published by Elsevier Ltd. All rights reserved.

488 C Giudice et al

immunoassayed with the standard ABC method,13

with antibodies anti-a smooth muscle actin (SMA)(clone 1A4), cytokeratin 14 (clone LL002), cytokeratin8/18 (clone UCD/PR-10.11), cytokeratin 19 (cloneb170) and Ki67 (clone MIB1). Aminoethylcarbazole(AEC) was used as a chromogen. In one case embed-ded material was insufficient for further sections. An-tibody origin, dilution and antigen retrieval methodsare summarised in Table 1.

The extent of fibrosis in the dermis surroundingcystic lesions was semi-quantitatively evaluated onMallory stained sections and scored as absent (0),mild (þ) moderate (þþ) and severe (þþþ).

Expression of Ki67 (MIB1) was quantitatively as-sessed with a video camera (CoolSNAP-Pro cf, MediaCybernetics) linked to an automatic image analysissystem (Image Pro Plus 4.5, Media Cybernetics). In10 random high power fields (HPF, 400�), the numberof MIB1 positive stained nuclei and the total numberof cell nuclei were evaluated and the relative percent-age of stained nuclei was calculated and indicated asproliferative index (PI).

ResultsNine hidrocystomas were obtained from a total of1658 feline biopsies (of which 54 were eyelid lesions).All hidrocystomas were diagnosed in Persian cats,seven males, two females, aged, at the time of diagno-sis, 3e15 years old (mean 9.6; median 8.5). Clinicaldata and the main pathological results are summar-ised in Table 2.

Seven cases of hidrocystomas were referred, in clin-ical records, as variably sized dark coloured palpebralnodules (Fig 1); 2/9 cases were described as tense,dark reddish, cysts (Fig 2). The most common differ-ential diagnosis posed by clinicians was eyelid mela-noma. All cats were free from cutaneous lesions,other than on the eyelid skin.

Grossly, on cut section, 5/9 samples revealed a cys-tic lesion that leaked a small amount of reddish tobrownish fluid; in 4/9 samples eyelid dermis wasfocally expanded with a spongy appearance.

Histologically, in 3/9 cases eyelid superficialdermis was expanded by a single large unilocular ormultilocular well delimited, unencapsulated cyst(0.3e0.9 cm) (Fig 3); in 2/9 cases multiple small cysts

Table 1. Antibodies used, clone dilution and unmask

Antibody Clone Host Source

a SMA 1A4 Mouse Dako Cytomation DeKi-67 MIB1 Mouse Dako Cytomation De

CK 8/18 UCD/PR-10.11 Mouse Zymed Lab, CA, USCK 14 LL002 Mouse Neomarkers, CA, US

CK 19 b170 Mouse Novocastra Lab, UK

were present beside a single large (0.5� 0.5 cm) cysticformation. In 4/9 cases multiple, variable sized, small(55e200 mm) cysts were detectable. In all cases, thecystic wall was lined by cuboidal to flattened epithe-lial cells arranged in a single layer and only occasion-ally rising in short papillary projections sustained bya thin fibrovascular branching core. Multifocal epithe-lial erosions were also present.

Epithelial cells were characterised by poorlydefined cell borders, moderate to abundant finelyvacuolated eosinophilic cytoplasm, occasionally withapical bulbous expansion (decapitation secretion),and voluminous oval, basally located, nuclei witha single prominent nucleolus.

No cell atypia was observed, except for case 4where moderate anisokaryosis and anisocytosis werepresent. Mitoses were usually not detected, exceptfor cases 4 and 8 (0e2 mitoses�HPF) (Fig 4).

The epithelium of the cyst laid on a single row ofspindle cells with minimal amount of lightly eosino-philic cytoplasm and small, oval, dense nuclei (myoe-pithelial cells). The cystic lumen was filled witha variable amount of amorphous homogeneous eosin-ophilic proteinaceous material, containing scatteredred blood cells, foamy macrophages loaded with in-tracytoplasmic yellowish granular pigment (ceroid),non-degenerated neutrophils and, occasionally, largeneedle shaped crystals (cholesterol).

A mild, diffuse inflammatory cell infiltration,mostly composed by lymphocytes, plasma cells,macrophages, a lesser numbers of neutrophils anda few scattered mast cells, was present in surround-ing dermis. In two cases (5 and 8) a small dermalaggregate of foamy macrophages and fewer multi-nucleated giant cells containing abundant intracyto-plasmic ceroid pigment admixed with smallcholesterol crystals (lipophagic granuloma) waspresent.

Dermal fibrosis was scored as mild in 2/9 cases, mod-erate in 6/9 cases (Fig 5) and severe in one single case.

In one case (case 9) a small (0.4 cm) well-differenti-ated tubular adenocarcinoma of apocrine gland wasalso present in the eyelid dermis close to the cysticlesions.

In all cases, overlaying eyelid epidermis wasdiffusely, moderately hyperplastic, with focal mildspongiosis and orthokeratotic hyperkeratosis.

ing technique adopted

Dilution Retrival method

nmark A/S 1:2000 Nonenmark A/S 1:600 Pressure steamer, buffer

citrate (pH 6), 20 min1:200 Pepsin digestion (37 �C) 10 min1:2000 Pressure steamer, buffer citrate

(pH 6), 10 min1:200 Pepsin digestion (37 �C) 10 min

Table 2. Clinical data and the main pathological results

Case Sex Age Numberof cysts

Size of maincyst (cm)

Mitoses/HPF 400�

Cellatypia

Fibrosisscore

Ki67 Approximatedevelopmenttime (months)

Clinical diagnosis

1 F 8 1 0.3� 0.3 0 � 2 9, 66 nd Palpebral nodule2 M 8 2 0.5� 0.5 0 � 2 19, 03 2 Cyst3 M 8.5 2 0.5� 0.5 0 � 2 nd 36 Cyst4 F 12 1 0.9� 0.7 0e2 þ 1 19, 06 2 Palpebral nodule5 M 12 Multiple Small* 0 � 3 16, 67 nd Palpebral nodule6 M 13 Multiple 0.4� 0.3 0 � 1 nd 24 Multiple palpebral

nodules7 M 3 1 0.6� 0.3 0 � 2 5, 30 nd Palpebral nodule8 M 7 Multiple Small* Occasional � 2 12, 62 12 Pigmented nodule9 M 15 Multiple Small* 0 � 2 20, 83 nd Pigmented

nodules

Fibrosis score: 0¼ absent; 1¼mild, 2¼moderate; 3¼ severe; nd¼ not determined.*Multiple, variably sized cysts ranging in diameter form 55 to 200 mm.

489Apocrine gland of Moll cysts in cats

Immunohistochemically, in 7/8 cases tested a dif-fuse and intense intracytoplasmic staining with cyto-keratin 8/18 and 19 was observed in epithelial cellslining cystic wall. A small rim of flattened, a SMAand CK14 positive cells surrounded cyst epithelium(myoepithelial cells) in 7/8 cases. Ki67/MIB1 nuclearstaining was detected in 7/8 samples; PI ranged from5.3 to 20.83 in different cases (mean 14.74; median16.67; SD 5.73) (Fig 6). In normal Moll’s glands in-cluded in the specimens, only few, scattered nucleistained Ki67/MIB1 positive (mean PI 1.9).

One case (case 6) was poorly reactive to immuno-histochemical staining, probably due to prolongedformalin fixation.

At the time of this paper, none of the hidrocystomashad recurred.

Fig 1. Male, Persian cat, 8.5 years old. A single, large, tense,smooth, dark brownish cyst is visible on the medial canthusat the eyelid margin. The lesion has been present for 3 years,with minimal size variations.

DiscussionHidrocystoma are benign cystic lesions of sweatapocrine glands that, in man, can originate bothfrom eccrine and apocrine glands. Apocrine hidrocys-toma usually appear as a single cystic nodule on theface, occasionally on ears and scalp.14e16

In the eyelids, hidrocystomas originate from apo-crine sweat gland of Moll and usually present as mul-tiple lesions on the lid margins.14,17 Moll glandhidrocystomas have been described, in man, as spo-radic findings or along with a constellation of othersigns, ie, hypodontia, hypotrichosis, palmoplantar hy-perkeratosis and onychodystrophy, as part of a rareautosomal recessive ectodermal dysplasia syndrome,the SchopfeSchulzePassarge syndrome.18,19

In the feline species, a few cases of multiple eyelidapocrine cysts, resembling Moll apocrine hidrocys-toma of human beings, have been described.9e12

None of the cats in previous reports, as well as those

Fig 2. Male, Persian cat, 15 years old. Multiple, small,smooth, pigmented nodules are present on upper eyelidmargins.

Fig 3. A single cyst expands the superficial eyelid dermis.Conglomerates of ceroid-loaded macrophages, admixedwith fewer lymphocytes, are present within cystic lumen.Haematoxylin and eosin, 12.5�.

Fig 5. Multiple, irregularly shaped, variably sized cysts arevisible in eyelid dermis, surrounded by moderate dermalfibrosis (blue stained collagen). Mallory staining, 40�.

490 C Giudice et al

examined in this series, had clinical signs consistentwith ectodermal dysplasia (as described in man), andfor all of them multiple eyelid cysts were the onlycomplaint.

Most cases of feline eyelid hidrocystomas reported sofar have been observedin Persian cats, suggesting a breed

Fig 4. Epithelial cells lining cystic wall form short papillaryprojection protruding within lumen. Cells are characterisedby moderate amount of eosinophilic, finely vacuolated cyto-plasm and large vesicular nuclei, with single prominent nu-cleolus. A mitotic figure is present (arrow). Haematoxylinand eosin, 400�.

predisposition.9e12 Our data seem to confirm this hy-pothesis, as all cats in our caseload were of Persian breed.

No sex predisposition has been reported for eyelidhidrocystomas in humans or cats, and an equal num-ber of female and male cats have been reported to beaffected. In our series of cases male cats were overrep-resented (seven males vs two females), however, thisfinding could reflect the distribution of the feline pop-ulation and not related to an actual sex predisposition.

Consistently with previous reports in the feline spe-cies,9,10 hidrocystomas in our caseload were mostlyobserved in older cats, with a median age of 8 years.

Clinical, gross and histological features of our caseswere consistent with previous reports of human andfeline hidrocystomas. The dark colour of the lesionscould be ascribed to the presence of blood, haemosi-derin and ceroid pigments within cyst lumen. Thesefindings in turn being related to focal epithelial ulcer-ation and secondary haemorrhages.

Fig 6. Multiple, scattered nuclei are intensely and diffuselyimmunolabelled with MIB1 antibody. MIB1/Ki67 immunos-taining, chromogen AEC (intense red-brown staining), 200�.

491Apocrine gland of Moll cysts in cats

The immunophenotype of epithelial cells lining cys-tic lesions (CK8/18 and CK19 positive) and of underly-ing myoepithelial cells (a SMA and CK14 positive) wasmost consistent with apocrine gland features.20

The aetiopathogenesis of hidrocystoma, both in hu-man and feline species, is debated and hidrocystomashave been variably interpreted as apocrine gland re-tention cysts or as benign neoplasms.4,8,10,15 Epithe-lium flattening and dermal fibrosis around cysticstructures apparently support the hypothesis of a re-tention cyst.8 On the other hand, high proliferative in-dices and epithelial papillary projections have beenconsidered features of neoplastic transformation.5,10

Based on our data, no definite conclusion concern-ing hidrocystoma aetiopathogenesis was possible, al-though, according to previous authors,10 the PI (Ki67immunostaining) observed, relatively high when com-pared with normal Moll’s gland epithelium, sug-gested a proliferative nature of these cystic lesions.

The presence of the relevant amount of dermal fi-brosis in all samples tested could be interpreted asplaying a role in cyst formation, but also as a lesionsecondary to compression exerted by hidrocystomaon surrounding dermis.

Further studies on a larger number of specimensare needed to confirm the proliferative nature of thisrare condition.

AcknowledgementsThe authors are grateful to all those colleagues thatprovided cases for this study, specifically: Dr AdolfoGuandalini, Dr Damiano Stefanello, Dr Re Calegari,Dr Anna Refatti and Dr Fumagalli.

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