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Multiple gastric adenomatous polyps in a dog
J. COMP.PATH. 196% VOL.B.
MULTIPLE
465
GASTRIC IN
ADENOMATOUS A DOG
POLYPS
BY
J. D. CONROY Dtportment of Vtitnhary Pathology and Hygim,
Uniwbity
of Illinois,
Urbana,
U.S.A.
INTRODUCTION
While carcinoma of the stomach has been reported in dogs, benign gastric neoplasms are thought to be very rare (Jubb and Kennedy, 1963). Brodey and Cohen (1964) reported one adenoma among 24 gastric neoplasms of dogs studied at the University of Pennsylvania, Philadelphia. One adenoma was observed among 20 gastric neoplasms out of a total of 5,854 canine neoplasms reported by Smith and Jones (1966). This case of multiple gastric adenomatous polyps in a dog is reported because of : (1) the paucity of information on benign gastric neoplasms, (2) the relatively young age of the affected dog, and (3) the observation of focal changes within the growth which suggested malignant transformation. The latter finding may bear on the pathogenesis of canine gastric carcindmas. RESULTS
Clinical Features A mongrel bitch, 1 to 14 years of age was presented in a debilitated condition, with vomiting, abdominal distention and diarrhota. Death occurred 2 days later. Pathological Findings A necmpsy was performed by the veterinary practioner, who reported that the stomach wall was firm and consisted of thi&ned folds and multiple solitary tumours of the mucous membrane involving almost the whole stomach. An undetermined quantity of ascitic fluid also was observed. Representative material fmm the stomach was submitted to the laboratory for microscopical diagnosis. The fixed specimens were firm polypoid or sessile growths which averaged 2 x 2.5 x 2.5 cm. and were yellowish-white on their cut surface (Fig. 1). The mucosa of the rugae was thickened. Microscopical examination of the gastric masses indicated that they were from the fundic region as shown by the comparatively short length of the gastric pits and the abundance of par&al cells. The mucous membrane was greatly thickened due to the adenomatous hyperplasia (Fig. 2). Many of the glandular elements were dilated. A thick connective tissue s&.lk which gave rise to secondary branches was observed beneath the epithelial ielements and lamina prop& Limited numbers of lymphocytes admixed with Iplasma cells were found in the lamina propria. Several foci of epithelial cells had limited atypical changes and
466
GASTRIC
ADENOMATOLJS
POLYPS
IN
A DOG
one adenoid focus (Figs. 3 and 4) had features suggestive of malignant transformation. These consisted of hyperchromasia of cells, papillary formations, “piling-up” and loss of polarity of cell layers, and a greater incidence of mitotic figures than in other areas of the neoplasm. The microscopical diagnosis was multiple gastric adenomatous polyps with focal atypical changes, suggesting malignant transformation. DISCUSSION
In man, carcinoma is the most common epithelial tumour of the stomach, benign epithelial tumours being relatively infrequent (Willis, 1960). Although epithelial neoplasms of the stomach occur much less frequently in dogs, nearly all reports published have been of carcinomas, indicating that, as in man, this is the most common type. The occurrence of adenomatous polyps in a young dog stimulates comparison with the age prevalence of adenomatous polyps in man. Stout (1953) reported on 32 adenomatous polyps of man. The ages of the patients ranged from 22 years to 75 years and all but 2 patients were over 45 years of age. The dog was considerably younger, after conversion to a comparable human age, than the youngest human with adenomatous polyps reported by Stout. The areas of malignant transformation in the canine gastric polyp suggested that some gastric carcinomas of dogs may be derived from benign adenomatous polyps. The malignant potential of these neoplasms in man is generally accepted, and is supported not only by the fact that microscopical study disclosed carcinomatous changes in about 25 per cent. of them, but also by the occurrence of carcinomas together with benign epithelial neoplasms (Willis, 1960). Since only a few representative tumours were submitted for histopathological examination from the stomach of the dog, the presence of unequivocal carcinoma in an area of the stomach not examined cannot be ruled out. Hypertrophic gastritis (gastritis polyposa) was considered in the differential diagnosis. However, the microscopical features of hypertrophic gastritis described by Stout (1953), namely, normal or slightly thickened mucosa, oedema of the mucosa and submucosa, and elongation of mucus pits, were not observed in the canine lesion, It is not certain whether hypertrophic gastritis of man is precancerous. SUMMARY
A case of multiple gastric adenomatous polyps is described in a female dog aged 1 to 14 years. One polyp had focal atypical changes suggesting malignant transformation. The infrequent occurrence of epithelial neoplasms, especially benign ones, in the stomachs of dogs is emphasized, as well as the significantly higher incidence of both benign and malignant epithelial tumours in man than in domesticated animals. ACKNOWLEDGMENT
I am grateful to Dr. F. E. Husmann for providing tion and for submitting the tissue for microscopical
the history and clinical informaexamination.
J. D. CONROY
Fig. Fig.
1. Cut surface of a sessile adenomatous polyp from the fundic region (right). Encephaloid appearance of gastric mucosa adjacent to polyps -(left). 2. Adenomatous polyp. Hyperplasia of the mucosa with cystic gastric glands. Connective tissue H. & E. x 13. core (c) .
To face Page 466
GASTRIC
Gg. 3. Gg. 4.
ADENOMATOUS
POLYPS
IN A DOG
Adenoid focus with features suggestive of malignant transformation. H.&E. 160. Higher magnification of Fig. 3 showing papillary formation and “piling-up” of cellular lay H. & E. x 4
J.
D.
467
CONROY
REFERENCES
Brodey, H. S., and Cohen, D. (1964). Scient. Proc. 1OIst Annual Meeting Amer. vet. med. Ass., p. 171. Jubb, K. V. F., and Kennedy, P. C. (1963). Pathology of Domestic Animals, 2, 74, Academic Press; New York and London. Smith, H. A., and Jones, T. C. (1966). Veterinary Pathology, 3rd Ed., p. 270, Lea and Feblger; Philadelphia. Stout, A. P. (1953). Atlas of Tumor Pathology, Tumors of the Stomach, pp. 21-22, Armed Forces Institute of Pathology; Washington, D.C. Willis, R. A. (1960). Pathology of Tumors, pp. 393, 398, Butterworth; London. [Received
for
publication,
March
24th,
19691
MULTIPLE
465
GASTRIC IN
ADENOMATOUS A DOG
POLYPS
BY
J. D. CONROY Dtportment of Vtitnhary Pathology and Hygim,
Uniwbity
of Illinois,
Urbana,
U.S.A.
INTRODUCTION
While carcinoma of the stomach has been reported in dogs, benign gastric neoplasms are thought to be very rare (Jubb and Kennedy, 1963). Brodey and Cohen (1964) reported one adenoma among 24 gastric neoplasms of dogs studied at the University of Pennsylvania, Philadelphia. One adenoma was observed among 20 gastric neoplasms out of a total of 5,854 canine neoplasms reported by Smith and Jones (1966). This case of multiple gastric adenomatous polyps in a dog is reported because of : (1) the paucity of information on benign gastric neoplasms, (2) the relatively young age of the affected dog, and (3) the observation of focal changes within the growth which suggested malignant transformation. The latter finding may bear on the pathogenesis of canine gastric carcindmas. RESULTS
Clinical Features A mongrel bitch, 1 to 14 years of age was presented in a debilitated condition, with vomiting, abdominal distention and diarrhota. Death occurred 2 days later. Pathological Findings A necmpsy was performed by the veterinary practioner, who reported that the stomach wall was firm and consisted of thi&ned folds and multiple solitary tumours of the mucous membrane involving almost the whole stomach. An undetermined quantity of ascitic fluid also was observed. Representative material fmm the stomach was submitted to the laboratory for microscopical diagnosis. The fixed specimens were firm polypoid or sessile growths which averaged 2 x 2.5 x 2.5 cm. and were yellowish-white on their cut surface (Fig. 1). The mucosa of the rugae was thickened. Microscopical examination of the gastric masses indicated that they were from the fundic region as shown by the comparatively short length of the gastric pits and the abundance of par&al cells. The mucous membrane was greatly thickened due to the adenomatous hyperplasia (Fig. 2). Many of the glandular elements were dilated. A thick connective tissue s&.lk which gave rise to secondary branches was observed beneath the epithelial ielements and lamina prop& Limited numbers of lymphocytes admixed with Iplasma cells were found in the lamina propria. Several foci of epithelial cells had limited atypical changes and
466
GASTRIC
ADENOMATOLJS
POLYPS
IN
A DOG
one adenoid focus (Figs. 3 and 4) had features suggestive of malignant transformation. These consisted of hyperchromasia of cells, papillary formations, “piling-up” and loss of polarity of cell layers, and a greater incidence of mitotic figures than in other areas of the neoplasm. The microscopical diagnosis was multiple gastric adenomatous polyps with focal atypical changes, suggesting malignant transformation. DISCUSSION
In man, carcinoma is the most common epithelial tumour of the stomach, benign epithelial tumours being relatively infrequent (Willis, 1960). Although epithelial neoplasms of the stomach occur much less frequently in dogs, nearly all reports published have been of carcinomas, indicating that, as in man, this is the most common type. The occurrence of adenomatous polyps in a young dog stimulates comparison with the age prevalence of adenomatous polyps in man. Stout (1953) reported on 32 adenomatous polyps of man. The ages of the patients ranged from 22 years to 75 years and all but 2 patients were over 45 years of age. The dog was considerably younger, after conversion to a comparable human age, than the youngest human with adenomatous polyps reported by Stout. The areas of malignant transformation in the canine gastric polyp suggested that some gastric carcinomas of dogs may be derived from benign adenomatous polyps. The malignant potential of these neoplasms in man is generally accepted, and is supported not only by the fact that microscopical study disclosed carcinomatous changes in about 25 per cent. of them, but also by the occurrence of carcinomas together with benign epithelial neoplasms (Willis, 1960). Since only a few representative tumours were submitted for histopathological examination from the stomach of the dog, the presence of unequivocal carcinoma in an area of the stomach not examined cannot be ruled out. Hypertrophic gastritis (gastritis polyposa) was considered in the differential diagnosis. However, the microscopical features of hypertrophic gastritis described by Stout (1953), namely, normal or slightly thickened mucosa, oedema of the mucosa and submucosa, and elongation of mucus pits, were not observed in the canine lesion, It is not certain whether hypertrophic gastritis of man is precancerous. SUMMARY
A case of multiple gastric adenomatous polyps is described in a female dog aged 1 to 14 years. One polyp had focal atypical changes suggesting malignant transformation. The infrequent occurrence of epithelial neoplasms, especially benign ones, in the stomachs of dogs is emphasized, as well as the significantly higher incidence of both benign and malignant epithelial tumours in man than in domesticated animals. ACKNOWLEDGMENT
I am grateful to Dr. F. E. Husmann for providing tion and for submitting the tissue for microscopical
the history and clinical informaexamination.
J. D. CONROY
Fig. Fig.
1. Cut surface of a sessile adenomatous polyp from the fundic region (right). Encephaloid appearance of gastric mucosa adjacent to polyps -(left). 2. Adenomatous polyp. Hyperplasia of the mucosa with cystic gastric glands. Connective tissue H. & E. x 13. core (c) .
To face Page 466
GASTRIC
Gg. 3. Gg. 4.
ADENOMATOUS
POLYPS
IN A DOG
Adenoid focus with features suggestive of malignant transformation. H.&E. 160. Higher magnification of Fig. 3 showing papillary formation and “piling-up” of cellular lay H. & E. x 4
J.
D.
467
CONROY
REFERENCES
Brodey, H. S., and Cohen, D. (1964). Scient. Proc. 1OIst Annual Meeting Amer. vet. med. Ass., p. 171. Jubb, K. V. F., and Kennedy, P. C. (1963). Pathology of Domestic Animals, 2, 74, Academic Press; New York and London. Smith, H. A., and Jones, T. C. (1966). Veterinary Pathology, 3rd Ed., p. 270, Lea and Feblger; Philadelphia. Stout, A. P. (1953). Atlas of Tumor Pathology, Tumors of the Stomach, pp. 21-22, Armed Forces Institute of Pathology; Washington, D.C. Willis, R. A. (1960). Pathology of Tumors, pp. 393, 398, Butterworth; London. [Received
for
publication,
March
24th,
19691