Ординатура / Офтальмология / Английские материалы / Veterinary Ocular Pathology A Comparative Review_Dubielzig, Ketring, McLellan_2010

■It is not clear in which gland, or glands, the tumor originates, as the tumors can be seen in multiple locations within the orbit

•Morphologic features of diagnostic value include:

■The tissue submitted for evaluation may consist of only multiple translucent lobules, with no other tissue sampled

■The neoplastic cells are fully differentiated glandular secretory cells with abundant clear, vacuolated or granular cytoplasm

■A PAS stain highlights the mucinous nature of the cytoplasmic contents helping to demonstrate the secretory features of the cell cytoplasm

■Acini may or may not be present, but differentiated ducts are never seen

–The absence of ducts is a useful feature in distinguishing these tumor nodules from normal glandular tissue

–In some tumors a few non-neoplastic glandular lobules may be intermingled with several neoplastic lobules further confusing the picture regarding what glandular tissue of the origin of these tumors.

Secondary, metastatic neoplasms (Fig. 6.27)

•Nasal adenocarcinoma

■Adenocarcinomas often infiltrate into the orbit from the nasal cavity or paranasal sinuses of both cats and dogs

•Metastatic epithelial tumors to the orbit in cats (Fig. 6.27)

■In cats, but seldom in dogs, hematogenous metastasis may lead to orbital neoplasia

■These tumors may also invade the globe

■Likely primary sites include lung, nasal cavity, middle ear, oral cavity, conjunctiva, and mammary gland.

Comparative Comments

In terms of neoplastic diseases of the orbit, similarities exist between those found in the COPLOW collection and those received in human eye pathology laboratories. Lymphoproliferative lesions and leukemia commonly involve the orbit, as do metastatic lesions. The most common epithelial tumors of the lacrimal gland are pleomorphic adenoma, adenoid cystic carcinoma, and malignant mixed tumors. Lymphomas of the lacrimal gland are also common. As is the case in other species, the human orbit contains a variety of structures that give rise to tumors with neurogenic and neural crest differentiation, mesenchymal differentiation, as well as neoplasms arising in bone. Tumors may also involve the orbit by direct extension into the orbit from the sinuses, eyelids, skin, conjunctiva, the eye itself, the optic nerve, the intracranial cavity, and the lacrimal sac.

138

A

B

*

Figure 6.27  Feline orbital metastatic carcinoma. (A) Persian, 12 years old: the tumor resulted in exophthalmia and lagophthalmos. FNA of the superior nasal mass confirmed the diagnosis of squamous cell carcinoma.

(B) Low magnification photomicrograph of a feline globe showing metastatic carcinoma in blood vessels adjacent to the optic nerve. (C) High magnification photomicrograph showing neoplastic epithelial cells in vascular structures (arrows) and a desmoplastic stroma (*). The inset is higher magnification.

General orbital pathology

Yanoff, M., Fine, B.S., 2002. Ocular pathology, 5th edn. Mosby, St Louis, pp. 518–520.

Koch, S.A., 1969. The differential diagnosis of exophthalmos in the dog. J. Am. Anim. Hosp. Assoc. 5, 229–237.

McCalla, T.L., Moore, C.P., 1989. Exophthalmos in dogs and cats. Part II. Compend. Contin. Educ. Pract. Vet. 11, 911–926.

Calia, C.M., Kirschner, S.E., Baer, K.E., et al., 1994. The use of computed tomography scan for the evaluation of orbital disease in cats and dogs. Vet. Comp. Ophthalmol. 4, 24–30.

Rebhun, W.C., 1998. Exophthalmos in horses. Equine Vet. Edu. 10, 63–65.

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Orbital complications of dental disease

Ramsey, D.T., Marretta, S.M., Hamor, R.E.,

et al., 1996. Ophthalmic manifestations and complications of dental disease in dogs and cats. J. Am. Anim. Hosp. Assoc. 32, 215–224.

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Exot. Anim. Pract. 9, 657–665.

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Smith, M.M., Smith, E.M., La Croix, N., et al., 2003. Orbital penetration associated with tooth extraction. J. Vet. Dent. 20, 8–17.

Penetrating injuries and foreign bodies

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Grahn, B.H., Szentimrey, D., Pharr, J.W., et al., 1995. Ocular and orbital porcupine quills in the dog: a review and case series. Can. Vet. J. 36, 488–493.

Fungal infections of orbital tissues

Buyukmihci, N., 1982. Ocular lesions of blastomycosis in the dog. J. Am. Vet. Med. Assoc. 180, 426–431.

Albert, R.A., Whitley, R.D., Crawley, R.R., 1981. Ocular blastomycosis in the dog. Comp. Cont. Edu. Pract. Vet. 3, 303–311.

Gerds-Grogan, S., Dayrell-Hart, B., 1997. Feline cryptococcosis: a retrospective evaluation. J. Am. Anim. Hosp. Assoc. 33, 118–122.

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Willis, A.M., Martin, C.L., Stiles, J., 1999. Sino-orbital aspergillosis in a dog. J. Am. Vet. Med. Assoc. 214, 1644–1647, 1639.

Halenda, R.M., Reed, A.L., 1997. Ultrasound/ computed tomography diagnosis – fungal sinusitis and retrobulbar myofascitis in a cat. Vet. Radiol. Ultrasound. 38, 208–210.

Hamilton, H.L., Whitley, R.D., McLaughlin, S.A., 2000. Exophthalmos secondary to aspergillosis in a cat. J. Am. Anim. Hosp. Assoc. 36, 343–347.

Wilkinson, G.T., Sutton, R.H., Grono, L.R., 1982. Aspergillus spp infection associated with orbital cellulitis and sinusitis in a cat. J. Small Anim. Pract. 23, 127–131.

McLellan, G.J., Aquino, S.M., Mason, D.R., et al., 2006. Use of posaconazole in the

management of invasive orbital aspergillosis in a cat. J. Am. Anim. Hosp. Assoc. 42, 302–307.

Bacterial infection in the orbit

Collins, B.K., Moore, C.P., Dubielzig, R.R., et al., 1991. Anaerobic orbital cellulitis and septicemia in a dog. Can. Vet. J. 32, 683–685.

Grahn, B.H., Szentimrey, D., Battison, A., et al., 1995. Exophthalmos associated with frontal sinus osteomyelitis in a puppy. J. Am. Anim. Hosp. Assoc. 31, 397–401.

Homma, K., Schoster, J.V., 2000. Anaerobic orbital abscess/cellulitis in a Yorkshire Terrier dog. J. Vet. Med. Sci. 62, 1105–1107.

Canine ocular onchocerciasis

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Komnenou, A., Eberhard, M.L., Kaldrymidou, E., et al., 2002. Subconjunctival filariasis due to Onchocerca sp. in dogs: report of 23 cases in Greece. Vet. Ophthalmol. 5, 119–126.

Komnenou, A., Egyed, Z., Sréter, T., et al., 2003. Canine onchocercosis in Greece: report of further 20 cases and molecular characterization of the parasite and its Wolbachia endosymbiont. Vet. Parasitol. 118, 151–155.

Zarfoss, M.K., Dubielzig, R.R., Eberhard, M.L., et al., 2005. Canine ocular onchocerciasis in the United States: two new cases and a review of the literature. Vet. Ophthalmol. 8, 51–57.

Hermosilla, C., Hetzel, U., Bausch, M., et al., 2005. First autochthonous case of canine ocular onchocercosis in Germany. Vet. Rec. 156, 450–451.

Sreter, T., Szell, Z., 2008. Onchocercosis:

A newly recognized disease in dogs. Vet. Parasitol. 151, 1–13.

Extraocular polymyositis

Carpenter, J.L., Schmidt, G.M., Moore, F.M., et al., 1989. Canine bilateral extraocular polymyositis. Vet. Pathol. 26, 510–512.

Ramsey, D.T., Hamor, R.E., Gerding, P.A., et al., 1995. Clinical and immunohistochemical characteristics of bilateral extraocular polymyositis of dogs. In: 26th Annual Meeting of the American College of Veterinary Ophthalmologists, Newport, RI, pp. 130–132.

Allgoewer, I., Blair, M., Basher, T., et al., 2000. Extraocular muscle myositis and restrictive strabismus in 10 dogs. Vet. Ophthalmol. 3, 21–26.

Masticatory myositis

Shelton, G.D., Cardinet 3rd., G.H., Bandman, E., 1987. Canine masticatory muscle disorders: a study of 29 cases. Muscle Nerve 10, 753–766.

Gilmour, M.A., Morgan, R.V., Moore, F.M., 1992. Masticatory myopathy in the dog: a retrospective study of 18 cases. J. Am. Anim. Hosp. Assoc. 28, 300–306.

Vamvakidis, C.D., Koutinas, A.F., Kanakoudis, G., et al., 2000. Masticatory and skeletal muscle myositis in canine leishmaniasis (Leishmania infantum). Vet. Rec. 146, 698–703.

Evans, J., Levesque, D., Shelton, G.D., 2004. Canine inflammatory myopathies: a clinicopathologic review of 200 cases.

J. Vet. Intern. Med. 18, 679–691.

Feline restrictive orbital sarcoma, ‘pseudotumor’

Miller S A, van der Woerdt, A., Bartick, T.E., 2000. Retrobulbar pseudotumor of the orbit in a cat. J. Am. Vet. Med. Assoc. 216, 356–358, 345.

Billson, F.M., Miller-Michau, T., Mould, J.R., et al., 2006. Idiopathic sclerosing orbital

pseudotumor in seven cats. Vet. Ophthalmol. 9, 45–51.

van der Woerdt, A., 2008. Orbital inflammatory disease and pseudotumor in dogs and cats. Vet. Clin. North Am. Small Anim. Pract. 38, 389–401, vii–viii.

Dubielizig, R.R., Bell, C.M., Schobert, C.S., 2008. Feline orbital pseudotumor: a morphologic review of 14 cases. Proceedings of the American College of Veterinary Ophthalmologists 39th Annual Conference, Boston, MA, p 108.

Hsuan, J.D., Selva, D., McNab, A.A., et al., 2006. Idiopathic Sclerosing Orbital Inflammation. Arch. Ophthalmol. 124, 1244–1250.

Canine systemic histiocytosis

Paterson, S., Boydell, P., Pike, R., 1995. Systemic histiocytosis in the Bernese mountain dog. J. Small Anim. Pract. 36, 233–236.

Scherlie Jr., P.H., Smedes, S.L., Feltz, T., et al., 1992. Ocular manifestation of systemic histiocytosis in a dog. J. Am. Vet. Med. Assoc. 201, 1229–1232.

Cystic lesions

Martin, C.L., Kaswan, R.L., Doran, C.C., 1987. Cystic lesions of the periorbital region. Comp. Cont. Edu. Pract. Vet. 9, 1022–1030.

Davidson, H.J., Blanchard, G.L., 1991. Periorbital epidermoid cyst in the medial canthus of three dogs. J. Am. Vet. Med. Assoc. 198, 271–272.

Lane, C.M., Ehrlich, W.W., Wright, J.E., 1987. Orbital dermoid cyst. Eye 1 (Pt 4), 504–511.

Walde, I., Hittmair, K., Henninger, W., et al., 1997. Retrobulbar dermoid cyst in a dachshund. Vet. Comp. Ophthalmol. 7, 239–244.

Munoz, E., Leiva, M., Naranjo, C., et al., 2007. Retrobulbar dermoid cyst in a horse: a case report. Vet. Ophthalmol. 10, 394–397.

Speakman, A.J., Baines, S.J., Williams, J.M., et al., 1997. Zygomatic salivary cyst with

mucocele formation in a cat. J. Small Anim. Pract. 38, 468–470.

Grahn, B.H., Mason, R.A., 1995. Epiphora associated with dacryops in a dog. J. Am. Anim. Hosp. Assoc. 31, 15–19.

Zygomatic salivary mucocele

Knecht, C.D., 1970. Treatment of diseases of the zygomatic salivary gland. J. Am. Anim. Hosp. Assoc. 6, 13–19.

Schmidt, G.M., Betts, C.W., 1978. Zygomatic salivary mucoceles in the dog. J. Am. Vet. Med. Assoc. 172, 940–942.

Miller, P.E., Pickett, J.P., 1989. Zygomatic salivary gland mucocele in a ferret. J. Am. Vet. Med. Assoc. 194, 1437–1438.

Bartoe, J.T., Brightman, A.H., Davidson, H.J., 2007. Modified lateral orbitotomy for vision-sparing excision of a zygomatic mucocele in a dog. Vet. Ophthalmol. 10, 127–131.

Allgoewer, I., Jurina, K., Stockhaus, C., 2004. Canine zygomatic adenitis. Proceedings of the European College of Veterinary Ophthalmologists Annual Meeting, Berlin, p 40.

Orbital vascular malformations

Rubin, L.F., Patterson, D.F., 1965. Arteriovenous fistula of the orbit in a dog. Cornell Vet. 55, 471–481.

Millichamp, N.J., Spencer, C.P., 1991. Orbital varix in a dog. J. Am. Anim. Hosp. Assoc. 27, 56–60.

Tidwell, A.S., Ross, L.A., Kleine, L.J., 1997. Computed tomography and magnetic resonance imaging of cavernous sinus enlargement in a dog with unilateral exophthalmos. Vet. Radiol. Ultrasound. 38, 363–370.

Adkins, E.A., Ward, D.A., Daniel, G.B., et al., 2005. Coil embolization of a congenital orbital varix in a dog. J. Am. Vet. Med. Assoc. 227, 1928–1929, 1952–1954.

Orbital fat prolapse

Bedford, P.G., Barnett, K.C., Boydell, P., et al., Partial prolapse of the antero-medial corpus adiposum in the horse. Equine Vet. J. Suppl. 1990, 2–4.

Boydell, P., Schrammer, A., Pike, R., 1994. Corpus adiposum prolapse in the horse: 6 cases. Equine Vet. Edu. 6, 128–129.

Boydell, P., Paterson, S., Pike, R., 1996. Orbital fat prolapse in the dog. J. Small Anim. Pract. 37, 61–63.

Williams, D.L., Haggett, E., 2006. Surgical removal of a canine orbital lipoma. J. Small Anim. Pract. 47, 35–37.

Orbital neoplasia

LeCouteur, R.A., Fike, J.R., Scagliotti, R.H., et al., 1982. Computed tomography of orbital tumors in the dog. J. Am. Vet. Med. Assoc. 180, 910–913.

Kern, T.J., 1985. Orbital neoplasia in 23 dogs. J. Am. Vet. Med. Assoc. 186, 489–491.

Gilger, B.C., McLaughlin, S.A., Whitley, R.D., et al., 1992. Orbital neoplasms in cats: 21 cases (1974–1990). J. Am. Vet. Med. Assoc. 201, 1083–1086.

Gilger, B.C., Whitley, R.D., McLaughlin, S.A., 1994. Modified lateral orbitotomy for removal of orbital neoplasms in two dogs. Vet. Surg. 23, 53–58.

O’Brien, M.G., Withrow, S.J., Straw, R.C., et al., 1996. Total and partial orbitectomy for the treatment of periorbital tumors in 24 dogs and 6 cats: a retrospective study. Vet Surg 25, 471–479.

Baptiste, K.E., Grahn, B.H., 2000. Equine orbital neoplasia: a review of 10 cases (1983–1998). Can. Vet. J. 41, 291–295.

Hendrix, D.V., Gelatt, K.N., 2000. Diagnosis, treatment and outcome of orbital neoplasia in dogs: a retrospective study of 44 cases. J. Small Anim. Pract. 41, 105–108.

Attali-Soussay, K., Jegou J-P., Clerc, B., 2001. Retrobulbar tumors in dogs and cats: 25 cases. Vet. Ophthalmol. 4, 19–27.

Mason, D.R., Lamb, C.R., McLellan, G.J., 2001. Ultrasonographic findings in 50 dogs with retrobulbar disease. J. Am. Anim. Hosp.

Assoc. 37, 557–562.

Peiffer Jr., R.L., Simons, K.B., 2002. Orbital tumors. In: Peiffer Jr, R.L., Simons, K.B. (Eds.), Ocular tumors in animals and humans, 1st edn. Iowa State Press, Ames, IA, pp. 3–23.

Rebhun, W.C., 1982. Orbital lymphosarcoma in cattle. J. Am. Vet. Med. Assoc. 180, 149–152.

Court, E.A., Watson, A.D., Peaston, A.E., 1997. Retrospective study of 60 cases of feline lymphosarcoma. Austr. Vet. J. 75, 424– 427.

Rebhun, W.C., Del Piero, F., 1998. Ocular lesions in horses with lymphosarcoma: 21 cases (1977–1997). J. Am. Vet. Med. Assoc. 212, 852–854.

Aquino, S.M., Hamor, R.E., Valli, V.E., et al., 2000. Progression of an orbital T-cell rich B-cell lymphoma to a B-cell lymphoma in a dog. Vet. Pathol. 37, 465–469.

Ciekot, P.A., Powers, B.E., Withrow, S.J., et al., 1994. Histologically low-grade, yet biologically high-grade, fibrosarcomas of the mandible and maxilla in dogs: 25 cases (1982–1991). J. Am. Vet. Med. Assoc. 204, 610–615.

Costas, A., Castro, P., Muñoz, J.M., 2001. Primary orbital liposarcoma: case report and review of the literature. Int. J. Oral Maxillofac. Surg. 30, 170–172.

Multilobular tumors and hyperostotic syndromes affecting the calvarium

Pletcher, J.M., Koch, S.A., Stedham, M.A., 1979. Orbital chondroma rodens in a dog. J. Am. Vet. Med. Assoc. 175, 187–190.

Straw, R.C., LeCouteur, R.A., Powers, B.E., et al., 1989. Multilobular osteochondrosarcoma of the canine skull: 16 cases (1978–1988). J.

Am. Vet. Med. Assoc. 195, 1764–1769.

McCalla, T.L., Moore, C.P., Turk, J., et al., 1989. Multilobular osteosarcoma of the

mandible and orbit in a dog. Vet. Pathol. 26, 92–94.

Groff, J.M., Murphy, C.J., Pool, R.R., et al., 1992. Orbital multilobular tumour of bone in a dog. J. Small Anim. Pract. 33, 597–600.

Jones, J.C., Smith, M.M., Sponenberg, D.P.,

et al., 1997. Orbital multilobular tumor of bone in a Basset Hound. Vet. Comp. Ophthalmol. 7, 111–116.

Dernell, W., Straw, R., Cooper, M., et al., 1998. Multilobular osteochondrosarcoma in 39 dogs: 1979–1993. J. Am. Anim. Hosp. Assoc. 34, 11–18.

Thompson, K.G., Pool, R.R., 2002. Feline Osteochondromatosis. In: Meuten, D.J. (Ed.), Tumours in domestic animals, 4th edn. Iowa State Press, Ames, IA, pp. 258–259.

Dennis, R., Barnett, K.C., Sansom, J., 1993. Unilateral exophthalmos and strabismus due to craniomandibular osteopathy. J. Small Anim. Pract. 34, 457–461.

Pastor, K.F., Boulay, J.P., Schelling, S.H., et al., 2000. Idiopathic hyperostosis of the calvaria in five young bullmastiffs. J. Am. Anim. Hosp. Assoc. 36, 439–445.

Canine orbital meningioma

Barnett, K.C., Singleton, W.B., 1967. Retrobulbar and chiasmal meningioma in a dog. J. Small Anim. Pract. 8, 391–394.

Perez, V., Vidal, E., Gonzalez, N., et al., 2005. Orbital meningioma with a granular cell component in a dog, with extracranial

metastasis. J. Comp. Pathol. 133, 212– 217.

Mauldin, E.A., Deehr, A.J., Hertzke, D., et al., 2000. Canine orbital meningiomas: a review of 22 cases. Vet. Ophthalmol. 3, 11–16.

Buyukmihci, N., 1977. Orbital meningioma with intraocular invasion in a dog. Histology and ultrastructure. Vet. Pathol. 14, 521–523.

Dugan, S.J., Schwarz, P.D., Roberts, S.M., et al., 1993. Primary optic nerve meningioma and pulmonary metastasis in a dog. J. Am. Anim. Hosp. Assoc. 29, 11–16.

Adenocarcinoma and multilobular adenoma

Rebhun, W.C., Edwards, N.J., 1977. Two cases of orbital adenocarcinoma of probable

lacrimal gland origin. J. Am. Anim. Hosp. Assoc. 13, 691–694.

Buyukmihci, N., Rubin, L.F., Harvey, C.E., 1975. Exophthalmos secondary to zygomatic adenocarcinoma in a dog. J. Am. Vet. Med. Assoc. 167, 162–165.

Hirayama, K., Kagawa, Y., Tsuzuki, K., et al., 2000. A pleomorphic adenoma of the lacrimal gland in a dog. Vet. Pathol. 37, 353–356.

Wilcock, B., Peiffer Jr., R., 1988. Adenocarcinoma of the gland of the third eyelid in seven dogs. J. Am. Vet. Med. Assoc. 193, 1549–1550.

Carberry, C.A., Flanders, J.A., Harvey, H.J.,

et al., 1988. Salivary gland tumors in dogs and cats: a literature and case review.

J. Am. Anim. Hosp. Assoc. 24, 561–567.

Headrick, J.F., Bentley, E., Dubielzig, R.R., 2004. Canine lobular orbital adenoma: a report of 15 cases with distinctive features. Vet.

Ophthalmol. 7, 47–51.

Secondary and metastatic neoplasia

Gelatt, K.N., Ladds, P.W., Guffy, M.M., 1970. Nasal adenocarcinoma with orbital extension and ocular metastasis in a dog. J. Am. Anim. Hosp. Assoc. 6, 132–142.

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Veterinary Ocular Pathology

Feline conjunctival mucoepidermoid carcinoma

Canine conjunctival melanoma and melanocytoma

Feline conjunctival melanoma

Canine conjunctival hemangioma, hemangiosarcoma

Feline conjunctival hemangioma, hemangiosarcoma

Equine hemangioma, hemangiosarcoma, angiosarcoma

Canine conjunctival mast cell tumor Feline conjunctival mast cell tumor Canine conjunctival lymphoma Feline conjunctival lymphoma

Tumors of the canine third eyelid gland (nictitans gland)

Tumors of the feline third eyelid gland (nictitans gland)

Canine viral papilloma Cysts of the conjunctiva

Conjunctival squamous papilloma and reactive papilloma

A B

C D

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187CONJUNCTIVA (Fig. 7.1)

188Eyelid agenesis, hypoplasia, coloboma

Figure 7.1  Eyelid agenesis with posterior segment coloboma. (A) DLH, 10 months old: agenesis of the superior and lateral lid caused trichiasis and corneal irritation.

(B) Fundus of the cat in (A) showing a large temporal coloboma (arrow) of the posterior segment extending to the margin of the optic disc. (C) DSH, 6 months old: the lid defect resulted in trichiasis and a mild corneal irritation. (D) Fundus of the cat in (C) with a peripapillary coloboma of the posterior segment, which affects the optic disc (arrow).

Distichiasis, ectopic cilia and trichiasis

These conditions are common in purebred dogs, and are seldom encountered in other species

•Distichiasis is a condition characterized by abnormally positioned eye lashes/cilia, and is very commonly encountered in dogs

■The abnormal cilia emerge from the meibomian (tarsal) gland openings on the eyelid margins and make contact with the conjunctival and/or corneal surface causing variable irritation. Distichiasis seldom results in significant corneal disease

•The follicles of ectopic cilia may arise within the meibomian glands, but these cilia emerge on the bulbar surface of the eyelid, through the palpebral conjunctiva

■Ectopic cilia typically emerge through the central upper eyelid at the 12 o’clock position

■Unlike distichiasis, ectopic cilia are almost always associated with significant ocular surface irritation. Signs of ocular pain may be of sudden onset, related to the emergence of an ectopic cilia through the palpebral conjunctiva. Significant keratitis, often with ulceration, is a frequent secondary complication of ectopic cilia

•Trichiasis defines a condition in which hairs arising in a normal location are misdirected to contact the ocular surface, e.g. by an abnormality of facial conformation such as prominent nasal folds in the brachycephalic breeds of dog

•Eyes with these diagnoses in the COPLOW collection have been removed because of their secondary complications including severe keratitis, not because of the abnormal cilia or abnormal hair shafts per se.

Entropion and ectropion

•Entropion and ectropion are complex conformational defects resulting from:

■Congenital malformation of the eyelid margins (anatomic) such as excessive eyelid length or laxity or insufficient palpebral fissure length, relative to globe size

■Acquired disease secondary to neuromuscular dysfunction (atonic) or response to severe ocular pain (spastic)

■Scar tissue (cicatricial)

•Although very common in certain purebred dogs, these conditions are not described in detail in this text because the eyelid tissue is seldom submitted for evaluation, just the globe which is affected secondarily

•Entropion is defined as an inversion of the eyelid margin

■Entropion results in trichiasis and corneal disease that is often severe

•Ectropion is defined as an eversion of the eyelid margin

■Ectropion may lead to exposure of conjunctival surfaces, with secondary conjunctivitis but is rarely a factor in corneal disease. There are no globes in the COPLOW collection where a direct relationship between this eyelid disease and enucleation was expressed on the submission form.

Symblepharon syndrome (Fig. 7.2)

•Symblepharon refers to adhesion or fusion of conjunctival surfaces of the eyelids or third eyelid, to adjacent conjunctival

surfaces, or to the cornea. This may lead to obliteration of the conjunctival fornix

•This is usually an acquired condition secondary to severe inflammation that results in loss of integrity of the conjunctival and corneal epithelia

•Symblepharon is most commonly encountered in young cats, in which the cause is usually infection with feline herpesvirus-1 (FHV-1) early in life

•Eyes are most often submitted to the COPLOW collection because of severe corneal involvement, with associated corneal opacity or perforation

•Surgical correction of symblepharon is possible, but prevention of recurrent symblepharon can be a major postoperative challenge.

Conjunctival or corneal dermoid (Fig. 7.3)

•A dermoid is a form of choristoma, a congenital disease characterized by the focal occurrence of fully-differentiated, non-neoplastic tissue in an abnormal location. In this case, skin on the conjunctiva or cornea

•The disorder occurs sporadically in all species. In dogs, the temporal limbus is most commonly affected

•Dermoids are frequently a source of irritation, because of the presence of hair, leading to trichiasis, or they may act as a mass lesion that impacts ocular or eyelid function

•Surgical excision is curative, provided that care is taken to include the deepest margin of the dermoid.

Comparative Comments

Many of the basic differences in the pathology of the human eyelid, as compared with other species, stem from the difference in anatomy. Humans lack a nictitating membrane and do not

have a nictitans gland or Harderian gland component to their tears.

Human congenital anomalies of the eyelid, however, do parallel those seen in other species.

•Distichiasis, abnormally positioned eyelashes, is occasionally encountered in man

•Trichiasis, in which cilia in a normal location become misdirected, occurs, most often, as a result of disease rather than breed conformation

–An example is in the end stages of trachoma, a conjunctival infection by Chlamydia trachomatis. The resulting trichiasis, as in animals, abrades the corneal surface, leading to ulceration and scarring and is ultimately a major cause of blindness

–Another major cause of trichiasis in humans is ocular cicatricial pemphigoid, a chronic disorder that is characterized by recurrent conjunctival surface bullae, which may ultimately result in corneal scarring

•Entropion is distinguished from other disorders that result in lashes misdirected toward the globe by abnormal rotation of the eyelid margin toward the cornea and bulbar conjunctiva. Similar to other species, in humans the underlying cause of the malposition may be congenital, spastic, involutional, or due to scarring

•Ectropion, the turning outward of the eyelid margin away from the globe, in humans may be mechanical, cicatricial, paralytic, or involutional

•For both entropion and ectropion, successful treatment depends on recognition of the underlying pathophysiology.

145

INFLAMMATORY LESIONS OF

THE EYELID SKIN

Parasitic dermatitis in horses, cutaneous and ocular habronemiasis, ‘summer sores’ (Fig. 7.4)

•Nodular cutaneous or conjunctival lesions associated with the larval stage of the nematode parasites Draschia megastoma, Habronema majus, or H. muscae

■Adult nematodes infest the gastric glandular mucosa and their larvae are transmitted by flies, e.g. the housefly and stablefly, which serve as intermediate hosts. Larvae in feces are ingested by fly maggots and subsequently deposited on the horse skin, open wounds and mucous membranes from the mouthparts of the feeding adult fly

■Periocular lesions most frequently involve the medial canthus region

•Histologically, the lesions are characterized by a cavitated lesion containing a predominantly eosinophilic infiltrate, including aggregates of eosinophilic protein around collagen bundles or fragments of parasite larvae.

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Demodicosis (Fig. 7.5)

•Cutaneous demodicosis is a cutaneous acariasis caused by Demodex species mites. Demodicosis, predominantly due to Demodex canis infection, is most often seen as a clinical disease entity in dogs

•Small numbers of mites can be seen in normal skin but clinically affected individuals have large numbers of the parasites

•Mites inhabit the hair follicles, causing excessive keratin secretion and ultimately, a destructive, granulomatous dermatitis

•Localized demodicosis is a relatively common cause of periocular alopecia, erythema and hyperpigmentation in young dogs

•Most cases resolve spontaneously but a small proportion of cases progress to a generalized form of disease, which is frequently complicated by secondary pyoderma

•Clinical demodicosis in adults is most frequently encountered in immune suppressed individuals

•These mites are species-specific and D. cati or D. gatoi, D. caballi and D. folliculorum may affect cats, horses or humans, respectively.

Dermatophytosis (‘Ringworm’) (Fig. 7.6)

•The dermatophyte fungi Microsporum canis, Microsporum gypseum, or Trichophyton mentagrophytes may colonize hair follicles resulting in focal dermatitis. Clinical disease is frequently seen in cats, but is also a relatively common problem in dogs, horses and cattle

•Regional foci of crusting, alopecia or pustular inflammatory reaction are typically seen

•Histologically, fungal elements are seen within or adjacent to the hair shaft and are often associated with furunculosis.

Canine cutaneous histiocytosis, sterile cutaneous granuloma

•This idiopathic granulomatous disease of the canine skin may involve the periocular skin or eyelid margin. The disease is characterized by focal, or multi-focal, nodular lesions. Histologically, granulomatous inflammation is seen, with features of classical granuloma, i.e. a pyogranulomatous center surrounded by epithelioid macrophage cells

•This is considered by some to be the least aggressive condition in a spectrum of histiocytic mass lesions which also includes systemic histiocytosis and malignant histiocytosis

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