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Surgical removal of a canine orbital lipoma

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					CASE REPORT

Surgical removal of a canine
orbital lipoma
A 10-year-old, female, neutered Cairn terrier was presented with                                                  CASE HISTORY
a progressively enlarging, cream-white fluctuant subconjunctival                                                   A 10-year-old, neutered, female Cairn ter-
swelling in the right eye. A fine-needle aspirate performed under                                                  rier weighing 14 kg was presented with
                                                                                                                  a history of a slowly enlarging, painless,
topical anaesthesia showed that the mass contained lipomatous                                                     white mass in the dorsal conjunctival for-
tissue. Orbital ultrasonography showed the mass to have a distinct                                                nix. The dog had been managed for obe-
                                                                                                                  sity from the age of two years, with a
border and to extend into the posterior orbit. The mass was removed
                                                                                                                  commercial calorie-control diet and
via a conjunctival incision. It had a distinct capsule anteriorly, while                                          had previously had lipomatous inguinal
                                                                                                                  masses removed surgically. At the age of
the border of the mass was less readily identified in the posterior
                                                                                                                  eight years, she had been presented with
orbit. Histopathological examination showed the mass to be a                                                      a white mass evident under the conjunc-
                                                                                                                  tiva in the right eye. After referral to vet-
lipoma. The dog recovered uneventfully from surgery, and no
                                                                                                                  erinary ophthalmologists at a specialist
recurrence has been noted after 12 months.                                                                        centre, the differential diagnosis of lym-
                                                                                                                  phoma or prolapse of the orbital corpus
                                                                                                                  adiposum was suggested. A fine-needle
D. L. WILLIAMS        AND   E. HAGGETT*                       INTRODUCTION                                        aspirate biopsy was performed demon-
                                                                                                                  strating lipomatous tissue with a very
Journal of Small Animal Practice (2006)                                                                           low cell harvest, and the latter diagnosis
47, 35–37                                                    Orbital neoplasms are seen rarely in the
                                                             dog, almost always present as slowly                 was considered as being confirmed.
                                                             progressing, painless exophthalmos in                    Two years later, the white swelling had
                                                             older dogs, and are often malignant.                 enlarged to the point that conjunctivitis
                                                             A wide variety of tumour types can                   was evident with engorged conjunctival
                                                             occur in the orbit, with fibroma, menin-              vessels (Fig 1). The dog was represented
                                                             gioma, oseteosarcoma, and lymphosarcoma              with ocular irritation as corneal ulceration
                                                             being reported (Kern 1985, Hendrix                   had occurred. The dog was treated with
                                                             and Gelatt 2000). Orbital neoplasms                  topical fusidic acid (Fucithalmic Vet;
                                                             can be primary, arising in the orbit,                Leo Laboratories) and referred for assess-
                                                             or, less commonly, secondary, invading               ment to the primary author (D. L. W.).
                                                             from adjacent structures. The majority                   More detailed ophthalmic examination
                                                             of primary orbital neoplasms in the                  showed no degree of third eyelid pro-
                                                             dog are malignant, with regional infiltra-            trusion or any exophthalmos but a 4 mm
                                                             tion or distant metastasis being common.             ventral deviation of the globe and a large
                                                             Most orbital neoplasms are extraconal                fluctuant white mass protruding from
                                                             and thus result in exophthalmos, often               the dorsal conjunctival sac was obvious
                                                             with lagophthalmos and protrusion of                 (Fig 1). A degree of lagophthalmos was
                                                             the nictitating membrane. An intraconal              noted, which was caused by the size of
                                                             mass such as a meningioma may present                the palpebral lesion with ocular surface
                                                             as exophthalmos without third eyelid                 exposure, and is presumed to have led
                                                             protrusion, and a small number of                    to the corneal ulceration previously diag-
                                                             orbital tumours do present with subcon-              nosed. The epithelial erosion had healed,
                                                             junctival swelling; of 15 cases of lobular           with a small area of subepithelial fibrosis
                                                             orbital adenoma in a recent study, five               evident, together with ocular surface pig-
                                                             presented with subconjunctival masses                mentation, again presumed to be a manifes-
                                                             and two with retrobulbar space-occupy-               tation of exposure keratitis. Schirmer tear
                                                             ing lesions (Headrick and others                     tests were 17 mm/minute in the right eye
Department of Clinical Veterinary Medicine,                  2004). Here, we present a benign, orbital            and 14 mm/minute in the left. Intraocular
University of Cambridge, Madingley Road,                     space-occupying lesion with an unusual               pressure, as measured by applanation
Cambridge CB3 OES
                                                             presentation and with a lipomatous                   tonometry (Tonopen XL; Veterinary Spe-
*House and Jackson Veterinary Surgeons, Chevers
Pawn, Rookery Road, Blackmore, Ingatestone,                  pathology as yet unreported in the                   ciality Products), was 16 mmHg in the
Essex CM4 0LE                                                canine orbit.                                        right eye compared with 14 mmHg in

Journal of Small Animal Practice   Á Vol 47 Á January 2006 Á ª 2006 British Small Animal Veterinary Association                                             35
                                                          David L. Williams & Emily Haggett




FIG 1. Subconjunctival mass in upper eyelid      FIG 3. Conjunctiva incised (arrows define
                                                 retracted conjunctival edges) to reveal anterior
                                                 extent of orbital mass
                                                                                                             FIG 5. Mass after removal from orbit
the left. Ultrasonography identified a well-
demarcated lesion hyperechogenic when
compared with the surrounding orbit con-
                                                                                                             or of a lipoma. Prolapse of the corpus adi-
tents (Fig 2) and extending from the pos-
                                                                                                             posum is widely recognised in human
terior limit of the orbit to the conjunctival
                                                                                                             beings (Monner and others 1998) and
fornix, which was markedly displaced ante-
                                                                                                             has previously been reported in horses
riorly. A provisional diagnosis of orbital
                                                                                                             (Bedford and others 1990) and in dogs
lipoma was made, and the dog was prepared
                                                                                                             (Boydell and others 1996). The pathology
for transconjunctival surgery to remove the
                                                                                                             in these cases is then a malpositioning of
mass.
                                                                                                             normal orbital fat because of breakdown
   The tumour was resected under general
                                                                                                             of connective tissue normally holding
anaesthesia; a conjunctival incision was
                                                                                                             the tissue in the orbit. In the present case,
made over the mass (Fig 3) and blunt dis-
                                                                                                             although this diagnosis had been sug-
section was used to separate the mass from
                                                                                                             gested on examination at another specialist
surrounding orbital tissues (Fig 4). Very
                                                 FIG 4. After blunt dissection the mass is                   centre, the progression in size of the lesion
limited haemorrhage was encountered,             removed through the dorsal conjunctival                     and its ultrasonographic appearance sug-
and dissection of the mass was simple until      incision
                                                                                                             gested a neoplastic process rather than
the posterior limit of the mass was reached
when tumour margins became somewhat
                                                 Leo Laboratories) and analgesia provided
indistinct. Following excision of the mass,
                                                 with 2 mg/kg oral carprofen (Rimadyl;
the conjunctiva was closed with 0Á8 metric
                                                 Pfizer) for five days.
coated polyglactin 910 (Vicryl; Ethicon)
                                                     The mass measuring 4x2x1 cm (Fig 5)
and the dog was discharged with topical
                                                 floated upon fixation in 10 per cent formol
fusidic acid antibiosis (Fucithalmic Vet;
                                                 saline, suggesting a lipomatous origin. His-
                                                 topathology confirmed the mass to be pre-
                                                 dominantly composed of adipocytes with
                                                 some inflammatory cell infiltrate and a
                                                 thin, fibrous capsule at the periphery of
                                                 the lesion (Fig 6). No recurrence was noted
                                                 over 12 months of follow-up.


                                                 DISCUSSION

                                                 The presentation of this case, with a pre-
                                                 vious demonstration of lipid material
                                                                                                             FIG 6. Histopathology of the mass haematoxylin
FIG 2. Ultrasonogram showing extent of mass in   subconjunctivally, suggests a diagnosis of                  and eosin x200. Note adipocytes and capsule
orbit (arrows) bar 1 cm                          either a prolapsed orbital corpus adiposum                  (arrows)


36                                                   Journal of Small Animal Practice   Á Vol 47 Á January 2006 Á ª 2006 British Small Animal Veterinary Association
                                                                     Surgical removal of a canine orbital lipoma




merely an aberrant anatomical positioning                    tumours in 1990 reported only 0Á3 per                  CONCLUSION
of normal orbital fat.                                       cent to be lipomas. The question has to
   Orbital neoplasia has been widely                         be asked in Forrest’s series, then, as in             Here we present what is apparently the
reported in the dog as noted above (Kern                     the present case, whether the lesions                 first reported case of canine orbital lipoma,
1985, Hendrix and Gelatt 2000) but                           reported to be lipomas actually repre-                with an unusual presentation as a slowly
normally as an extraconal space-occupying                    sented normal orbital fat. What differen-             enlarging cream-white dorsal conjunctival
orbital lesion with exophthalmos and pro-                    tiates a low-grade lipoma from normal                 mass. Resection with a transconjunctival
trusion of the nictitating membrane. The                     orbital fat and thus leads us to suggest that         approach was successful in resolving the
dorsal position of the lesion here might sug-                the lesion presented here is a lipoma rather          condition.
gest a neoplasm of the lacrimal gland, as has                than another case of orbital fat prolapse?
been previously reported in the dog (Wang                        Lipoma suggests not the abnormal
and others 2001). The finding of fat on                       position of normal orbital fat but rather             References
fine-needle aspirate biopsy strongly sug-                     a neoplastic increase in the size of the              BEDFORD, P. G., BARNETT, K. C., BOYDELL, P. & HAIZELDEN,
gested a diagnosis of orbital lipoma or lipo-                orbital adipose tissue. Lipoma is benign                N. (1990) Partial prolapse of the antero-medial
                                                                                                                     corpus adiposum in the horse. Equine Veter-
matous haemangiopericytoma. The latter                       in appearance both grossly and on histo-
                                                                                                                     inary Journal Ophthalmology Supplement 2 10,
neoplasm has been reported in the orbit                      pathology, so mere observation of the                   2-4
in human beings and in dogs (Goldsmith                       mass at the time of resection cannot easily           BELTRAN, W. A., COLLE, M. A., BOULOUHA, L., DAUDE-
                                                                                                                     LAGRAVE, A., MOISSONNIER, P., CLERC, B. (2001) A
and others 2001, Beltran and others                          be used to differentiate orbital fat prolapse
                                                                                                                     case of orbital hemangiopericytoma in a dog. Vet-
2001) and may have lipomatous elements                       from lipoma. It is the behaviour of the                 erinary Ophthalmology 4, 255-259
(Davies and others 2002). Haemangioper-                      mass over time which differentiates orbital           BOYDELL, P., PATERSON, S. & PIKE, R. (1996) Orbital fat
icytoma, as a relatively aggressive vascular                 fat prolapse (essentially a non-progressive             prolapse in the dog. Journal of Small Animal Prac-
                                                                                                                     tice 37, 61-63
tumour is, however, to be differentiated                     lesion) from lipoma (a slowly enlarging               DAVIES, P. E., DAVIS, G. J., DODD, T., SELVA, D. (2002)
from lipoma on histopathological and                         space-occupying mass). The ultrasono-                   Orbital lipomatous haemangiopericytoma: an
behavioural grounds.                                         graphic appearance of the lesion in this                unusual variant. Clinical and Experimental Oph-
                                                                                                                     thalmology 30, 281-283
   To our knowledge, orbital lipoma,                         dog suggests a marked increase in size of             GOLDSMITH, J. D., VAN DE RIJN, M., SYED, N. (2001) Orbital
a widely recognised tumour in human                          the corpus adiposum enlarging over time.                hemangiopericytoma and solitary fibrous tumor:
beings, has not been reported in dogs.                       It is normally difficult to demarcate such               a morphologic continuum. International Journal
                                                                                                                     of Surgical Pathology 9, 295-302
The orbit contains the globe, the optic                      a corpus adiposum in the dog on orbital               HEADRICK, J. F., BENTLEY, E. & DUBIELZIG, R. R. (2004)
nerve, the extraocular muscles, the con-                     ultrasonography, and Boydell’s case series              Canine lobular orbital adenoma: a report of 15
nective tissue, and the neurovascular struc-                 found no abnormality in appearance in                   cases with distinctive features. Veterinary Oph-
                                                                                                                     thalmology 7, 47-51
tures, all of which are surrounded by                        the dogs in which orbital ultrasonography             HENDRIX, D. V., GELATT, K. N. (2000) Diagnosis, treat-
adipose tissue. Any of these tissues can                     was undertaken. Here, preoperative                      ment and outcome of orbital neoplasia in dogs:
undergo neoplastic change, but it is con-                    orbital ultrasonography demonstrated that               a retrospective study of 44 cases. Journal of Small
                                                                                                                     Animal Practice 41, 105-108
sidered that fat is the tissue which is least                the majority of the hyperechoic lesion was            KERN, T. J. (1985) Orbital neoplasia in 23 dogs. Jour-
likely to develop neoplastic change. In                      located in the posterior orbit and extended             nal of American Veterinary Medical Association
human beings, the prevalence of orbital                      posteriorly almost to the posterior wall of             186, 489-491
                                                                                                                   MONNER, J., BENITO, J. R., ZAYUELAS, J., PALOMA, V.,
lipomas in published series of orbital                       the orbit, a finding confirmed at surgery.                CASTRO, V. & SERRA, J. M. (1998) Transconjunctival
tumours ranges from 0 to 11 per cent.                        While ventral deviation of the globe was                herniation of orbital fat. Annals of Plastic Surgery
In two large series of orbital tumours,                      evident, it was the mass that protruded                 41, 658-661
                                                                                                                   WANG, F. I., TING, C. T., LIU, Y. S. (2001) Orbital ad-
Forrest’s study of 222 cases from 1949                       both subconjunctivally and thus extraorbi-
                                                                                                                     enocarcinoma of lacrimal gland origin in a dog.
reported 19 (8Á6 per cent) to be lipomas,                    tally rather than the globe being displaced             Journal of Veterinary Diagnostic Investigation
while Henderson’s review of 764 orbital                      forward.                                                13, 159-161




Journal of Small Animal Practice   Á Vol 47 Á January 2006 Á ª 2006 British Small Animal Veterinary Association                                                          37

				
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