Tumours of the eye and adnexa

Bull. Org. mond. Sante 1974, 50, 135-142 Bull. Wld Hlth Org. } X: Tumours ofthe eye and adnexa C. H. KIRCHER,' F. M. GARNER,2 & F. R. ROBINSON 3 Most types of epithelial tumour of the eyelids, conjunctiva, and cornea occur in all species; the most common type occurring in any species is bovine squamous cell carcinoma. Iridociliary epithelial tumours and malignant melanomas are the most important intra- ocular tumours. The histological features of the tumours are described under the following main headings: epithelial tumours of the eyelids, conjunctiva, and cornea; mesenchymal tumours (extraocular, optic nerve and nerve sheath, and uveal tract); neuroectodermal tumours; and melanogenic tumours of the eyelids and conjunctiva and of the uveal tract. This classification is based on the study of approxi- mately 300 cases of ocular tumours in domestic animals, on file at the Armed Forces Institute of Pathology (AFIP), Washington, D.C. Most types of epithelial tumour and tumour-like conditions of the eyelids, conjunctiva, and cornea occur in all species of domestic animal. The basal cell tumours, sebaceous gland tumours, and papil- lomas in the AFIP collection were all from dogs and cattle, but basal cell tumours have been reported to occur also in cats, and papillomas have been found in horses. Squamous cell carcinomas were found in cattle, horses, sheep, and dogs, but have been reported to occur also in swine and cats. Epidermal plaques were seen only in cattle. Ocular dermoids were found in cattle and dogs, but they have been reported to occur also in sheep and horses. Bovine squamous cell carcinoma, epidermal plaque, and papilloma are the most common ocular tumours of domestic animals and the most important from the economic point of view. In the USA they occur mainly in the Hereford breed and are seldom seen in other breeds, but in Africa, Asia, and Europe breeds other than the Hereford are often 1 Department of Pathobiology, University of Connecticut, Storrs, Connecticut, USA. 'Life Sciences Research Branch, Scientific Director, Bionectics Research Laboratory, Kensington, Md., USA. ' Head, WHO International Reference Center for Com- parative Oncology, Armed Forces Institute of Pathology, Washington, D.C., USA. The views expressed herein are those of the authors and do not necessarily reflect the views of the Departments of the Air Force, of the Army, or of Defense. affected. The incidence of these tumours has been related to the degree of pigmentation of periorbital skin and to long exposure to intense sunlight. There is evidence for a genetic basis of susceptibility. Reports indicate that the majority of these tumours arise from the medial or lateral limbus of the eye, the remainder arising from the palpebral conjunc- tiva, membrana nictitans, and skin of the eyelids. There is a much lower incidence of these tumours in other species. In the AFIP collection, extraocular mesenchymal tumours were found in the dog and horse. Tumours of fibrous tissue and peripheral nerves were more frequent in the horse. Histiocytomas and tumours of muscle and blood vessels were found only in the dog. Mast cell tumours were found in the dog and have been reported to occur in the horse. Only a few cases of meningioma and reticulosis were found and they occurred in the dog. Intra- ocular haemangioma and leiomyoma were found as single cases in the dog. Melanomas of the eyelids and conjunctiva were found in the dog and horse. Iridociliaryepithelialtumoursandmalignantmelan- omas are the most important intraocular tumours in animals. The former were studied only in the dog, whereas the latter were studied in the dog and cat. These tumours are rare in other species. Substantiated cases of retinoblastoma, medullo- epithelioma (diktyoma), and teratoid medulloepithe- lioma have not been reported in domestic animals. The Armed Forces Institute of Pathology kindly supplied Fig. 1, 2, and 4-10. 3172 - 135- C. H. KIRCHER ET AL. HISTOLOGICAL CLASSIFiCATION AND NOMENCLATURE OF TUMOURS OF THE EYE AND ADNEXA I. EPITHELIAL TUMOURS AND TUMOUR-LIKE LESIONS OF THE EYELIDS, CONJUNCTIVA, AND CORNEA A. BASAL CELL TUMOUR B. SQUAMOUS CELL CARCINOMA C. SEBACEOUS GLAND TUMOUR D. PAPILLOMA E. EPIDERMAL PLAQUE F. OCULAR DERMOID G. EPIDERMOIXD AND DERMOID CYSTS II. MESENCHYMAL TUMOURS A. ExTRAOCULAR 1. Tumours of fibrous tissue (a) Fibroma (b) Fibrosarcoma (c) " Equine sarcoid" 2. Tumours of muscle (a) Rhabdomyosarcoma 3. Tumours of blood vessels (a) Haemangioma (b) Haemangiosarcoma 4. Mesenchymal tumours of peripheral nerves (a) Perineural fibroblastoma (b) Neurofibrosarcoma 5. Mast cell tumour 6. Canine histiocytoma DESCRIPTION ( I. EPITHELIAL TUMOURS AND TUMOUR-LIKE LESIONS OF THE EYELIDS, CONJUNCTIVA, AND CORNEA Basal cell tumours (A), sebaceous gland tumours (C), and epidermoid and dermoid cysts (G) have the same morphological features as those of the skin generally. Therefore they are not described here, but in Part VII. Tumours of the skin. B. OPTIC NERVE AND NERVE SHEATH 1. Meningioma 2. Reticulosis C. UVEAL TRACT 1. Haemangioma 2. Leiomyoma III. NEUROECTODERMAL TUMOURS A. IRIDOCILIARY EPITHELIUM 1. Adenoma 2. Adenocarcinoma B. OTHER 1. ASTROCYTOMA IV. MELANOGENIC TUMOURS A. EYELID ANI) CONJUNCTIVA 1. Benign melanoma 2. Malignant melanoma B. UVEAL TRACT 1. Benign melanoma 2. Malignant melanoma (a) Spindle cell type (b) Epithelioid cell type (c) Mixed-cell type V. SECONDARY TUMOURS VI. UNCLASSIFIED TUMOURS )F TUMOURS B. Squamous cell carcinoma (Fig. 1) Squamous cell carcinomas of the eye or eyelids are similar to those of the skin and are morpho- logically similar in the different species. Thesetumours may be either well or poorly differentiated or they may contain areas of varying differentiation. Well- differentiated tumours have large polyhedral cells 136 Fig. 1. Squamous cell carcinoma, cornea (ox). AFIP neg. No. 74-3988. Fig. 3. Ocular dermoid(dog). University-of Connecticut. Fig. 2. Epidermal plaque, conjunctiva (ox). AFIP neg. No. 72-6037. Fig. 4. Adenoma, papillary (dog). AFIP neg. No. 72- 5753. Fig. 5. Adenoma, tubular (dog). AFIP neg. No. 72- 5740. Fig. 6. Adenoma, solid (dog). AFIP neg. No. 72-5759. Fig. 7. Adenocarcinoma (dog). AFIP neg. No. 72-3806. Fig. 8. Adenocarcinoma (dog). AFIP neg. No. 72-5974. Fg9.Mlgat melaoma spidl B S(dg)AI neg. No. 551541 -s v 4.?^s -> * ;!.)x* 'W'~~~% ' '>"4't h Fig. 9. Malignant melanoma, spindle B (dog). AFIP neg. No. 55-16541. Fig. 10. Malignant melanoma, epithelioid (cat). AFIP neg. No. 73-8108. Fig 11. Malignant melanoma, mixed, predominantly spindle cell (dog). University of Connecticut. Fig. 12. Malignant melanoma, mixed, predominantly epithelioid cell (dog). University of Connecticut. EYE AND ADNEXA similar to cells of the stratum spinosum, with inter- cellular bridges, and they often contain concentric laminations of keratin (" epithelial pearls "). Poorly differentiated tumours are highly anaplastic and have small, hyperchromatic cells with no keratinization. Squamous cell carcinomas involving the cornea or bulbar conjunctiva may invade the eye. Distant metastases develop late via the lymphatics and usu- ally arise from tumours involving the palpebral con- junctiva, skin of the eyelid, or membrana nictitans. D. Papilloma This tumour has multiple papillary projections with central connective tissue cores and a prolifera- tive epithelial covering. The epithelium may be hyperkeratotic. E. Epidermal plaque (Fig. 2) This consists in a thickening of the epithelium, characterized by acanthosis and hyperkeratosis. The surface is not papillary but pseudoepitheliomatous hyperplasia and subepithelial inflammation may occur. In cattle, early squamous cell carcinoma may arise at the base of papillomas and epidermal plaques. Nests of cells, usually in the basilar layer, have hyperchromatic nuclei, increased numbers of mitoses, pleomorphism, and loss of polarity. There is inva- sion of immediate subepithelial tissue by tumour cells. F. Ocular dermoid (Fig. 3) This is a noncystic developmental malformation arising from the conjunctiva at the limbus. It resem- bles skin with stratified squamous keratinized epi- thelium, hair follicles, and adnexal glands in a dense collagenous connective tissue. II. MESENCHYMAL TUMOURS A. Extraocular Extraocular mesenchymal tumours are morpho- logically the same as those described and illustrated in Part VIII. Tumours of soft tissues. B. Optic nerve and nerve sheath Meningioma and reticulosis are described and illustrated in Part V. Tumours of the nervous system. C. Uveal tract 1. Haemangioma. This consists of a mass of vas- cular spaces lined with mature endothelial cells separated by a loose collagenous stroma. 2. Leiomyoma. ln this tumour, densely packed spindle-shaped cells are arranged in long streams and whorls. The nuclei are elongated, with parallel sides, rounded ends, and finely stippled chromatin. In the single report in a dog, mitotic figures and necrosis suggested malignancy. III. NEUROECTODERMAL TUMOURS A. Iridociliary epithelium 1. Adenoma (Fig. 4-6). This tumour is derived from mature, differentiated ciliary or iris epithelium. The tumour cells are well differentiated and are cuboidal, columnar, or slightly spindle-shaped. The round nuclei are small to moderate in size, with granular chromatin and a nucleolus. Mitotic fig- ures are infrequent. Pigmentation, with large mel- anin granules, varies and some tumours are non- pigmented. The stroma may contain normal, heavily pigmented melanocytes or melanophages. Extension into the stroma of the iris or ciliary body or into the filtration angle may occur and does not neces- sarily indicate malignant change. This tumour may form papillary or tubular structures, which may be compact, with little stroma, or it may form a loose network with an abundant mucoid stroma. Portions of the tumour may form solid sheets of cells with minimal stroma. 2. Adenocarcinoma (Fig. 7, 8). This tumour arises from mature, differentiated iridociliary epithelium. It has pronounced cytological variation, more numer- ous mitotic figures, and definite invasiveness. Tumour cells are pleomorphic and may be spindle-shaped, polyhedral, or columnar. Tumours may form solid sheets of cells, gland-like structures, and papillary structures. Pigmentation of tumour cells is variable. The stroma is usually delicate and may contain nor- mal pigmented cells. Areas of haemorrhage and necrosis may occur in large tumours. This tumour is locally destructive but has little tendency to meta- stasize. B. Others Astrocytomas are rare. They are morphologically the same as those of the central nervous system and are described and illustrated in Part V. Tumours of the nervous system. 11 141 C. H. KIRCHER ET AL. IV. MELANOGENIC TUMOURS A. Eyelids and conjunctiva Benign and malignant melanomas of the eyelids and conjunctiva do not differ morphologically from those of the skin. They are described in Part VII. Tumours of the skin. B. Uveal tract 1. Benign melanoma. Benign melanomas of the uveal tract have not been found in animals, although they occur in man. However, several normal accu- mulations of melanocytes may be mistaken for tumours. Numerous melanocytes are normally found in the lamina cribosa of the eye in many species. Corpora nigra-accumulations of pigmented iris epithelial cells-are prominent on the dorsal margins of the pupil in horses and less prominent in ruminant animals. 2. Malignant melanoma. This is a group of malig- nant melanocytic tumours exhibiting a marked varia- tion in both cytological composition and degrees of pigmentation. There is a spectrum of cell types rang- ing from spindle A and B types to the epithelioid type. Most tumours contain some admixture of these cell types. Spindle cell melanomas containing both A and B cell types are classified as spindle B. Tumours containing both prominent spindle cells and epithe- lioid cells are classified as mixed-cell type. In animals, this mixed-cell type is most frequent. In man, the cell type of malignant melanomas has prognostic value: spindle cell tumours have a favourable prog- nosis, whereas epithelioid cell tumours have a poor prognosis and mixed-cell types have an intermediate prognosis. However, a correlation between cell types and prognosis has not been established for animal tumours. (a) Spindle cell type (Fig. 9). The tumour cells may be either slender, spindle-shaped cells with flattened, ovoid nuclei without nucleoli (spindle A) or more plump with larger, more ovoid nuclei with prominent nucleoli (spindle B). Spindle B type tumours are much more common. Mitotic figures are usually low in number and pigmenta- tion is variable. The tumour cells have a compact, cohesive pattern of growth. In a fascicular type of spindle cell tumour the cells and nuclei are in a palisade arrangement resembling patterns observed in perineural fibro- blastomas. (b) Epithelioid cell type (Fig. 10). The tumour cells are much larger than spindle cells and are polyhedral or slightly spindle-shaped with moder- ate to abundant acidophilic cytoplasm and some- times indistinct cytoplasmic membranes. Nuclei are large and round or irregular with more pro- minent nucleoli and there is a higher mitotic activity than in spindle cell types. The tumour cells appear to be less cohesive than in spindle cell tumours. A few epithelioid cell type tumours have smaller, more uniform cells with scanty cytoplasm and small round nuclei with inconspicuous nucleoli. Mitotic figures are rare. (c) Mixed-cell type (Fig. 11, 12). These tumours are composed of varying proportions of spindle and epithelioid cells. V. SECONDARY TUMOURS Lymphosarcoma is the most important metastatic tumour of the eye and orbit. Other tumours meta- static to the eye have been reported as rare or single cases. 142