OSSIFYING AMELOBLASTOMA IN A HORSE
P.M. SUMMERS*§, K. E. WELLst and K . F. ADKINSS SUMMARY: The features of an ossifying ameloblastoma in a 5-year-old gelding are described. The tumour developed in the angle of the right mandible and microscopically consisted of multiole follicles and islands of eDithelial tissue adjacent to which were trabeculae of bone, osteoid and compact collagenous h u e .
Introduction
Tumours of odontogenic origin are uncommon in man and the domesticated animals (Moulton 1961; Gorlin et a1 1963). The ameloblastoma is the more common of the epithelial odontogenic tumours and is believed t o arise either from epithelial remnants of the embryonic tooth or, less frequently, from the basal layer of the oral mucous membrane (Gorlin et a1 1963). Cases of ameloblastomas in the horse have been reported by Gorlin et a1 (1963), Vaughan and Bartels (1968), and Hanselka eta1 (1974). This report describes an ameloblastoma in a horse with the unusual feature of extensive ossification of the mesenchymal tissues. History and Clinical Examination
A 5-year-old trotter gelding was presented for clinical examination because of progressive loss of weight and development of a swelling on the right mandible over a period of 3 months. There was a firm non-painful swelling approximately lOcm in diameter at the angle of the right mandible and marked atrophy of the right masseter muscle and tissues above and below the zygomatic arch. The animal had difficulty in mastication and oral examination showed a soft swelling of tissue posterior to the lower right 6th molar. The lesion increased in size over the subsequent 3 weeks and the horse was killed and an autopsy conducted. Autopsy Findings
At autopsy, a tumour approximately lOcm in diameter was present in the angle of the right mandible partly surrounding the root of the 6th molar tooth. The right masseter muscle and tissues above and below the right zygQmatic arch were atrophied. 'Queensland Department of Primary Industries, Animal Research Institute, 665 Fairfield Rd. Yeerongpilly, Queensland 4105 6Prerenr Addrear: Department o f Immunoloev. J o h n Curtin School of hledical Research, Auslralian National University, P.O. Box 334, Canberra, Australian Capital Territory, 2601 t 6 5 Grafton Sr., W a w i c k , Queensland 4370 *Department of Oral Biology. University of Queensland. St Lucia. Queensland 4067
498
The tumour was a discrete, soft and gelatinous lesion and was pale green to light yellow in colour on a cut surface. Multiple calcified foci were detected on cutting the tumour. There was a marked resorption of the medial and lateral aspects of the mandibular bone surrounding the tumour but the tumour had not perforated the bone. Seven small blocks of tissue from the tumour were fixed in 10% formalin, paraffin-embedded and sectioned at 6 um for histological examination. Some blocks were decalcified using the formic acidlsodium citrate technique. The following stains were applied to sections of decalcified and undecalcified tissue: Harris's haematoxylin and eosin, Masson's trichrome, Alcian blue for acidic mucopolysaccharides, von Kossa and Alizarin red S for calcium, periodic acid-Schiff reaction and Mallory's phosphotungstic acid haematoxylin. Histopathology
Epithelial tissue was prominent throughout the tumour and ranged from small islands, cords and anastomosing strands interspersed by loose, well vascularised connective tissue to larger follicles and masses of epithelial cells. The periphery of the follicles was formed by a layer of columnar cells resembling ameloblasts arranged uniformly and perpendicular to the basement membrane with distinct polarisation of nuclei away from the basement membrane (Figure 1). Towards the centre of the follicles, the cells were loosely connected and had a stellate appearance often with microcyst formation (Figure 2). Occasional larger cysts were lined partially or completely by a narrow zone of epithelial cells. Scattered foci of epithelial cells displayed an acanthomatous appearance, often associated with formation of keratin and in some areas of the tumour, there was extensive necrosis of the epithelial follicles. Mitotic figures were rarely detected. Widely distributed throughout the tumour and immediately adjacent to the epithelial tissue were trabeculae of heavily calcified tissue morphologically resembling bone, osteoid and nonAustralian Veterinary Journal, Vol. 55, October, 1979
calcified compact collagenous tissue (Figures 1 and 2). In most trabeculae there was a sharp line of demarcation between calcified and noncalcified tissue. Calcification occurred centrally in the trabeculae and lagged considerably behind the rate of formation of bone matrix. Individual cells in lacunae were present throughout the calcified and non-calcified areas of the trabeculae, and at the end of the trabeculae there were accumulations of mesenchymal cells with oval or spherical nuclei and pale indistinct cytoplasm (Figure I), small groups of which were sometimes enveloped by the compact collagenous tissue. Discussion
The most striking and unusual. feature of this odontogenic tumour was the presence of bone and bone matrix immediately adjacent to the epithelial tissues. Otherwise, the tumour had all the characteristics of an ameloblastoma (Pindborg and Kramer 1971).We have been unable to find a specific report of an ossifying ameloblastoma occurring in man or animals although the reports of ameloblastomas in horses by Vaughan and Bartels (1968) and Hanselka et a1 (1974) suggest that there may have been some bone formation in those cases. It is also of note that Jubb and Kennedy (1970) refer to osteoid formation occurring in some ameloblastomas in animals. The formation of bone and bone matrix was interpreted as indicating inductive influences of epithelium over the connective tissue elements as the inductive effect of one type of odontogenic tissue upon another is well known (Gorlin 1970). In normal tooth development, ameloblasts in the enamel organ enduce undifferentiated mesenchymal cells immediately adjacent to them to dif-
ferentiate into odontoblasts. The odontoblasts then begin to form dentin which reciprocally induces ameloblasts to form enamel. The length of the ameloblast-like cells and polarisation of their nuclei to the extent seen in this tumour is unusual in ameloblastomas. In normal odontogenic tissues, polarisation of nuclei is a prominent feature of ameloblasts with the nuclei being situated o n the basal end of the cells. The apex of the ameloblast is associated with the inductive effects on the mesenchymal tissues in particular enamel matrix formation. Ameloblastomas are benign but locally aggressive tumours and in man, the majority are found in the molar region of the mandible during the third and fourth decade of life (Shafer et a1 1974). Similar observations have been made in domesticated animals (Moulton 1961). The case described by Vaughan and Bartels (1968) involved the mandibular symphysis of a 14-year-old stallion and that by Hanselka et a1 (1974) occurred in the mandible of an 11-year-old mare. Clinical details of the cases described by Gorlin et a1 (1963) were not reported. The only other odontogenic tumour which has been described in the horse is the ameloblastic odontoma, a tumour composed of epithelial tissues and dentin, cementum and enamel. Cases have been reported by Gorlin et af (1963), Peter er al(1968) and Lingard and Crawford (1970). Acknowledgments
tumour and offered advice regarding its classification. Technical assistance was provided by K . Schultz. References Gorlin, R. J. (1970) - In Tboma’s Oral Pathology, p 481, 6th edn., The C. V. Mosby Company, St Louis. Gorlin, R. J., Meskin, L. H. and Brodey, R. (1963) -Ann. N . Y . Acad. Sci. 108: 723. Hanselka, D. V., Roberts, R. E. and Thompson, R. B. (1974) - Vet. Med. small Anim. Clin. 69: 157. Jubb, K. V. F. and Kennedy, P . C. (1970) - In Pathology of Domestic Animals, Vol. 11, p 40. Academic Press, New York and London. Lingard, D. R. and Crawford, T. B. (1970) - Am. J. vet. Res. 31: 801.
Moulton, J . E. (1961) - In Tumours of Domestic Animals, p 127. University of California Press, Berkeley and Los Angeles. Peter, C. P. Myers, V. S. and Ramsey, F. K . (1968) - Am. J . vet. Res. 29: 1495. Pindborg, J. J. and Kramer, K. R. H . (1971) - Histological Typing of Odontogenic Tumours, Jaw Cysts and Allied Lesions. International Histological Classification of Tumours no. 5. Wld Hlth Org., Geneva. Shafer, W. G., Hine, M. K . and Levy, B. M. (1974) - In A Textbook of Oral Pathology, p 254, 3rd edn. W. B. Saunders Comoanv. Philadelohia. Vaughan, J. T. and Bartels, J.’E. (1968) - J. Am. vet. med. Ass. 153: 454. (Accepted for publication 6 May 1979)
OBITUARY WILLIAM PETER CLIFFORD RICHARDS Peter Richards die1 iuddenly on 25 June at his home in Werribee, Victoria. The profession has lost one of its most outstanding veterinary pathologists and teachers. Many around the’ world will be deeply saddened by his death. Peter was born in Burwood, New South Wales, in 1931, and received his high school education at Newington College, Stanmore. In 1952 he graduated B.Sc. with honours from the University of Sydney, majoring in geology and agricultural chemistry. He resisted strong persuasion to pursue a career in geology to enrol in veterinary science. After a brilliant undergraduate career he graduated as a Bachelor of Veterinary Science with first class honours in 1957 and was awarded a University Medal. After working for a year at the Veterinary Research Station, Glenfield, New South Wales, Peter went to Canada to pursue postgraduate studies at the Ontario Veterinary College, Guelph. He was awarded the degree M.V.Sc. in 1960 for a thesis entitled Studies on a new encephaloniyelitis of swine in Ontario. From 1960 to 1967 Peter was a lecturer and later Assistant Professor of Veterinary Pathology, School of Veterinary Medicine, University of California at Davis. There he was also enrolled as a graduate student in the program o f Comparative Pathology. With rare brilliance he filled his teaching duties and for a thesis titled Pathologic responses of the mature a n d developing nervous system to bluetongue virus he was awarded the degree Ph.D. Peter returned to Australia in 1970 to take u p the position of Senior Lecturer in Veterinary Pathology in the University of Melbourne. He was a member of the Australian College of Veterinary Scientists and by examination of a member of the American College of Veterinary Pathologists. He was an enthusiastic supporter of the Australian Association of Vererinary Pathologists, being a regular contributor to annual pathology training courses and an executive member since the
500
foundation of the Association. He was also elected to membership of Sigma Xi, Phi Zeta and Phi Kappa Phi. He was the author of more than 20 original publications, many concerned with neuropathology. Several of his publications, namely those concerned with viral encephalomyelitis of pigs and the pathology of abortion caused by bovine herpesvirus type 1, are standard reference works. No formal listing of Peter Richards’ curriculum vitae could possibly do justice to the total contributions ‘that he made. He was an outstanding teacher and lecturer of both undergraduate and postgraduate students. His ability to read slides for diagnostic veterinary pathology was unsurpassed. He gave of his time and wisdom in uncountable hours particularly to postgraduate students. His forte was perhaps the pathology seminars at Davis or the ‘5.15. sessions’ at Werribee where the air sparkled with his definitive, clear statements; the arguments were always good - he seldom lost any - and everyone learned. In similar vein Peter also convened periodically the ‘Saturday afternoon slide seminars’ that were much valued by his professional colleagues. There was never a silence when Peter was around. He had a fondness for a deep sense of feeling for his fellow man, irrespective of their walk in life and all derived a deeper understanding of themselves and a warm affection for Peter by knowing him. Peter’s feelings and understanding of people were perhaps outshone by the rapport between him and those animals he chose as his most constant companions. Diabetes, which he developed about 1973, increasingly troubled his life. He is survived by his sister, Betty, and a beloved Aunt Nance. (M.J.S. & K . L . H . )
Australian Veterinary Journal, Vol. 55, October, 1979
P.M. SUMMERS*§, K. E. WELLst and K . F. ADKINSS SUMMARY: The features of an ossifying ameloblastoma in a 5-year-old gelding are described. The tumour developed in the angle of the right mandible and microscopically consisted of multiole follicles and islands of eDithelial tissue adjacent to which were trabeculae of bone, osteoid and compact collagenous h u e .
Introduction
Tumours of odontogenic origin are uncommon in man and the domesticated animals (Moulton 1961; Gorlin et a1 1963). The ameloblastoma is the more common of the epithelial odontogenic tumours and is believed t o arise either from epithelial remnants of the embryonic tooth or, less frequently, from the basal layer of the oral mucous membrane (Gorlin et a1 1963). Cases of ameloblastomas in the horse have been reported by Gorlin et a1 (1963), Vaughan and Bartels (1968), and Hanselka eta1 (1974). This report describes an ameloblastoma in a horse with the unusual feature of extensive ossification of the mesenchymal tissues. History and Clinical Examination
A 5-year-old trotter gelding was presented for clinical examination because of progressive loss of weight and development of a swelling on the right mandible over a period of 3 months. There was a firm non-painful swelling approximately lOcm in diameter at the angle of the right mandible and marked atrophy of the right masseter muscle and tissues above and below the zygomatic arch. The animal had difficulty in mastication and oral examination showed a soft swelling of tissue posterior to the lower right 6th molar. The lesion increased in size over the subsequent 3 weeks and the horse was killed and an autopsy conducted. Autopsy Findings
At autopsy, a tumour approximately lOcm in diameter was present in the angle of the right mandible partly surrounding the root of the 6th molar tooth. The right masseter muscle and tissues above and below the right zygQmatic arch were atrophied. 'Queensland Department of Primary Industries, Animal Research Institute, 665 Fairfield Rd. Yeerongpilly, Queensland 4105 6Prerenr Addrear: Department o f Immunoloev. J o h n Curtin School of hledical Research, Auslralian National University, P.O. Box 334, Canberra, Australian Capital Territory, 2601 t 6 5 Grafton Sr., W a w i c k , Queensland 4370 *Department of Oral Biology. University of Queensland. St Lucia. Queensland 4067
498
The tumour was a discrete, soft and gelatinous lesion and was pale green to light yellow in colour on a cut surface. Multiple calcified foci were detected on cutting the tumour. There was a marked resorption of the medial and lateral aspects of the mandibular bone surrounding the tumour but the tumour had not perforated the bone. Seven small blocks of tissue from the tumour were fixed in 10% formalin, paraffin-embedded and sectioned at 6 um for histological examination. Some blocks were decalcified using the formic acidlsodium citrate technique. The following stains were applied to sections of decalcified and undecalcified tissue: Harris's haematoxylin and eosin, Masson's trichrome, Alcian blue for acidic mucopolysaccharides, von Kossa and Alizarin red S for calcium, periodic acid-Schiff reaction and Mallory's phosphotungstic acid haematoxylin. Histopathology
Epithelial tissue was prominent throughout the tumour and ranged from small islands, cords and anastomosing strands interspersed by loose, well vascularised connective tissue to larger follicles and masses of epithelial cells. The periphery of the follicles was formed by a layer of columnar cells resembling ameloblasts arranged uniformly and perpendicular to the basement membrane with distinct polarisation of nuclei away from the basement membrane (Figure 1). Towards the centre of the follicles, the cells were loosely connected and had a stellate appearance often with microcyst formation (Figure 2). Occasional larger cysts were lined partially or completely by a narrow zone of epithelial cells. Scattered foci of epithelial cells displayed an acanthomatous appearance, often associated with formation of keratin and in some areas of the tumour, there was extensive necrosis of the epithelial follicles. Mitotic figures were rarely detected. Widely distributed throughout the tumour and immediately adjacent to the epithelial tissue were trabeculae of heavily calcified tissue morphologically resembling bone, osteoid and nonAustralian Veterinary Journal, Vol. 55, October, 1979
calcified compact collagenous tissue (Figures 1 and 2). In most trabeculae there was a sharp line of demarcation between calcified and noncalcified tissue. Calcification occurred centrally in the trabeculae and lagged considerably behind the rate of formation of bone matrix. Individual cells in lacunae were present throughout the calcified and non-calcified areas of the trabeculae, and at the end of the trabeculae there were accumulations of mesenchymal cells with oval or spherical nuclei and pale indistinct cytoplasm (Figure I), small groups of which were sometimes enveloped by the compact collagenous tissue. Discussion
The most striking and unusual. feature of this odontogenic tumour was the presence of bone and bone matrix immediately adjacent to the epithelial tissues. Otherwise, the tumour had all the characteristics of an ameloblastoma (Pindborg and Kramer 1971).We have been unable to find a specific report of an ossifying ameloblastoma occurring in man or animals although the reports of ameloblastomas in horses by Vaughan and Bartels (1968) and Hanselka et a1 (1974) suggest that there may have been some bone formation in those cases. It is also of note that Jubb and Kennedy (1970) refer to osteoid formation occurring in some ameloblastomas in animals. The formation of bone and bone matrix was interpreted as indicating inductive influences of epithelium over the connective tissue elements as the inductive effect of one type of odontogenic tissue upon another is well known (Gorlin 1970). In normal tooth development, ameloblasts in the enamel organ enduce undifferentiated mesenchymal cells immediately adjacent to them to dif-
ferentiate into odontoblasts. The odontoblasts then begin to form dentin which reciprocally induces ameloblasts to form enamel. The length of the ameloblast-like cells and polarisation of their nuclei to the extent seen in this tumour is unusual in ameloblastomas. In normal odontogenic tissues, polarisation of nuclei is a prominent feature of ameloblasts with the nuclei being situated o n the basal end of the cells. The apex of the ameloblast is associated with the inductive effects on the mesenchymal tissues in particular enamel matrix formation. Ameloblastomas are benign but locally aggressive tumours and in man, the majority are found in the molar region of the mandible during the third and fourth decade of life (Shafer et a1 1974). Similar observations have been made in domesticated animals (Moulton 1961). The case described by Vaughan and Bartels (1968) involved the mandibular symphysis of a 14-year-old stallion and that by Hanselka et a1 (1974) occurred in the mandible of an 11-year-old mare. Clinical details of the cases described by Gorlin et a1 (1963) were not reported. The only other odontogenic tumour which has been described in the horse is the ameloblastic odontoma, a tumour composed of epithelial tissues and dentin, cementum and enamel. Cases have been reported by Gorlin et af (1963), Peter er al(1968) and Lingard and Crawford (1970). Acknowledgments
tumour and offered advice regarding its classification. Technical assistance was provided by K . Schultz. References Gorlin, R. J. (1970) - In Tboma’s Oral Pathology, p 481, 6th edn., The C. V. Mosby Company, St Louis. Gorlin, R. J., Meskin, L. H. and Brodey, R. (1963) -Ann. N . Y . Acad. Sci. 108: 723. Hanselka, D. V., Roberts, R. E. and Thompson, R. B. (1974) - Vet. Med. small Anim. Clin. 69: 157. Jubb, K. V. F. and Kennedy, P . C. (1970) - In Pathology of Domestic Animals, Vol. 11, p 40. Academic Press, New York and London. Lingard, D. R. and Crawford, T. B. (1970) - Am. J. vet. Res. 31: 801.
Moulton, J . E. (1961) - In Tumours of Domestic Animals, p 127. University of California Press, Berkeley and Los Angeles. Peter, C. P. Myers, V. S. and Ramsey, F. K . (1968) - Am. J . vet. Res. 29: 1495. Pindborg, J. J. and Kramer, K. R. H . (1971) - Histological Typing of Odontogenic Tumours, Jaw Cysts and Allied Lesions. International Histological Classification of Tumours no. 5. Wld Hlth Org., Geneva. Shafer, W. G., Hine, M. K . and Levy, B. M. (1974) - In A Textbook of Oral Pathology, p 254, 3rd edn. W. B. Saunders Comoanv. Philadelohia. Vaughan, J. T. and Bartels, J.’E. (1968) - J. Am. vet. med. Ass. 153: 454. (Accepted for publication 6 May 1979)
OBITUARY WILLIAM PETER CLIFFORD RICHARDS Peter Richards die1 iuddenly on 25 June at his home in Werribee, Victoria. The profession has lost one of its most outstanding veterinary pathologists and teachers. Many around the’ world will be deeply saddened by his death. Peter was born in Burwood, New South Wales, in 1931, and received his high school education at Newington College, Stanmore. In 1952 he graduated B.Sc. with honours from the University of Sydney, majoring in geology and agricultural chemistry. He resisted strong persuasion to pursue a career in geology to enrol in veterinary science. After a brilliant undergraduate career he graduated as a Bachelor of Veterinary Science with first class honours in 1957 and was awarded a University Medal. After working for a year at the Veterinary Research Station, Glenfield, New South Wales, Peter went to Canada to pursue postgraduate studies at the Ontario Veterinary College, Guelph. He was awarded the degree M.V.Sc. in 1960 for a thesis entitled Studies on a new encephaloniyelitis of swine in Ontario. From 1960 to 1967 Peter was a lecturer and later Assistant Professor of Veterinary Pathology, School of Veterinary Medicine, University of California at Davis. There he was also enrolled as a graduate student in the program o f Comparative Pathology. With rare brilliance he filled his teaching duties and for a thesis titled Pathologic responses of the mature a n d developing nervous system to bluetongue virus he was awarded the degree Ph.D. Peter returned to Australia in 1970 to take u p the position of Senior Lecturer in Veterinary Pathology in the University of Melbourne. He was a member of the Australian College of Veterinary Scientists and by examination of a member of the American College of Veterinary Pathologists. He was an enthusiastic supporter of the Australian Association of Vererinary Pathologists, being a regular contributor to annual pathology training courses and an executive member since the
500
foundation of the Association. He was also elected to membership of Sigma Xi, Phi Zeta and Phi Kappa Phi. He was the author of more than 20 original publications, many concerned with neuropathology. Several of his publications, namely those concerned with viral encephalomyelitis of pigs and the pathology of abortion caused by bovine herpesvirus type 1, are standard reference works. No formal listing of Peter Richards’ curriculum vitae could possibly do justice to the total contributions ‘that he made. He was an outstanding teacher and lecturer of both undergraduate and postgraduate students. His ability to read slides for diagnostic veterinary pathology was unsurpassed. He gave of his time and wisdom in uncountable hours particularly to postgraduate students. His forte was perhaps the pathology seminars at Davis or the ‘5.15. sessions’ at Werribee where the air sparkled with his definitive, clear statements; the arguments were always good - he seldom lost any - and everyone learned. In similar vein Peter also convened periodically the ‘Saturday afternoon slide seminars’ that were much valued by his professional colleagues. There was never a silence when Peter was around. He had a fondness for a deep sense of feeling for his fellow man, irrespective of their walk in life and all derived a deeper understanding of themselves and a warm affection for Peter by knowing him. Peter’s feelings and understanding of people were perhaps outshone by the rapport between him and those animals he chose as his most constant companions. Diabetes, which he developed about 1973, increasingly troubled his life. He is survived by his sister, Betty, and a beloved Aunt Nance. (M.J.S. & K . L . H . )
Australian Veterinary Journal, Vol. 55, October, 1979
