Vet Patho129:552-553 (1992)

Mammary Carcinoma with Peritoneal Metastasis in a Cow M.

B.

PETRITES-MURPHY

Key words: Carcinoma; cattle; mammary gland.

In contrast to the dog and cat, mammary neoplasia is rare in the cow. A review of the literature by Ford et al.' revealed only 41 cows with primary mammary gland neoplasia since 1902. Ten of those cases involved mammary carcinomas. This report is of an additional case of mammary carcinoma with an unusual pattern of metastasis. An 8-year-old Simmental cow was recumbent for a day before dying. The carcass was submitted for necropsy 12 hours after death. The left front quarter of the mammary gland was uniformly firm and pink on incision, but was not enlarged. The other three-quarters were soft and tan. The peritoneal cavity contained approximately 4 liters of light yellow, clear fluid. Numerous white nodules, approximately 2 ern in diameter, were distributed throughout the mesentery and adhered to the serosal surfaces of the liver, spleen, and diaphragm (Fig. I). Aspirated plant material was seen in the bronchi. There was no evidence of neoplasia in the thoracic cavity, the reproductive tract, or the gastrointestinal tract. Microscopically, approximately one-halfof the mass of the mammary gland was neoplastic. The neoplasm was a welldifferentiated ductular and acinar carcinoma (Fig. 2). Clusters of neoplastic acini were interspersed with normal-appearing acini, and a transition from normal to neoplastic epithelium was evident in many acini (Fig. 3). Acini were lined by a single layer of cuboidal or flattened cells that often formed papillary projections that filled the lumen. Cells had round to oval vesicular nuclei, variable nuclear size, and approximately one mitotic figure per high-powered field (0.45 mm in diameter). The peritoneal nodules were composed of tubules with only slight invasion of the organs to which the tumors were attached. The tubules were filled with macrophages and degenerated cells and were embedded in a fibrous stroma. They were lined by a single layer of columnar to

cuboidal epithelial cells with well-developed apical microvilli and oval vesicular nuclei. The cytoplasm and tubular lumens of both the primary tumor and the metastatic nodules contained periodic acid-Schiff-positive material, which was resistant to diastase digestion. This was more pronounced in the metastatic tumor than in the primary tumor. Metastasis of mammary tumors is not common, even in the dog. In a study of424 canine mammary tumors, Cotchindiagnosed 187 malignant tumors, of which only 41 metastasized. A review of the literature of canine mammary carcinomas found that of those that had proven metastases, the percentage of involvement of different organs was as follows: lymph nodes 64%, lungs 53%, liver 13%, kidney II %, heart II %, and bone 10%.6 There are too few cases of bovine mammary carcinoma to determine the expected pattern of metastasis. Of the ten cases of bovine mammary carcinoma reported in the literature, six metastasized to the lymph nodes. L7 Of these six cases, one had metastasis to the lungs, a second case had metastasis to the lungs, liver, and diaphragm, and a third case spread to the lungs, pleura, pericardium, and kidney. Peritoneal metastasis was not mentioned in any of the bovine cases. Implantation of tumors on serosal surfaces is more common in cases of cholangiocellular carcinoma, ovarian carcinoma, bovine and ovine intestinal carcinoma, and equine gastric squamous cell carcinoma.' Because of the extensive serosal implantation of the tumor, in this case a differential diagnosis considered was peritoneal mesothelioma with concomitant mammary carcinoma. This possibility was ruled out by the histologic similarity of the tumors in both the mammary gland and the peritoneal cavity, and the presence of periodic acid-Schiff-positive diastase-resistant material within the tubular lumens of the peritoneal tumor.' Due to the rare occurrence of mammary tumors in cows, the risk factors and the biological behavior of bovine mammary carcinoma are virtually unknown. This is in sharp contrast to the high rate of human mammary carcinoma (any carcinoma arising in the glandular and ductular structures of the breast). Epidemiological data support a role for hyperestrinism in the genesis of human breast cancer. 8 Pregnancy shortens such exposure to estrogen. The low rate of mammary carcinoma in cattle may be partially due to the high rate of pregnancy in this species. Estrogen levels were not determined in this cow, so that theory cannot be addressed in this case. However, this case description augments the few cases ofbovine mammary carcinoma that have been reported and assists in the future discernment of the biological behavior of this rare neoplasm.

Acknowledgement Fig. 1. Diaphragm; cow. A metastatic tumor is evident on the peritoneal surface. HE. Bar = I mm.

The investigation reported in this paper (No. 91-4-108) was done in connection with a project of the Kentucky Ag-

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Brief Communications and Case Reports

Vet Pathol 29:6, 1992

Fig. 2. Bar = 50 Fig. 3. Bar = 25

Mammary gland, carcinoma; cow. Neoplastic cells form aberrant acini surrounded by mature fibrous tissue. HE. }.Lm.

Mammary gland, carcinoma; cow. Both normal and neoplastic epithelial cells are evident in the acini. HE. }.Lm.

ricultural Experiment Station and is published with the approval of the Director.

References

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Beamer PD, Simon J: Mammary carcinoma in a cow. Vet PathoI20:509-510, 1983 Cotchin E: Mammary neoplasms of the bitch. J Comp Pathol 68: 1-22, 1958 Ford TS, Ross MW, Acland HM, Madison JB: Primary teat neoplasia in two yearling heifers. J Am Vet Med Assoc 195:238-239, 1989 Julian RJ: The peritoneum, retroperitoneum, and mesentery.In: Pathology of Domestic Animals, ed. Jubb KVF, Kennedy PC, and Palmer N, 3rd ed., pp. 329-342. Academic Press, Orlando, FL, 1985 McCaughey WTE, Kannerstein M, Churg J: Diffuse ma-

lignant mesothelioma. In: Tumors and Pseudotumors of the Serous Membranes, ed. Hartmann WH, pp. 20-72. Armed Forces Institute of Pathology, Washington, DC, 1985 6 Moulton JE: Tumors of the mammary gland. In: Tumors in Domestic Animals, ed. Moulton JE, 3rd ed., pp. 518552. University of California Press, Berkeley, CA, 1990 7 Povey RC, Osborne AD: Mammary gland neoplasia in the cow. Vet PathoI6:502-512, 1969 8 Robbins SL, Cotran RS: The breast. I n: Pathological Basis of Disease, 2nd ed., pp. 1305-1335. WB Saunders, Philadelphia, PA, 1979 Request reprints from Dr. M. B. Petrites-Murphy, Livestock Disease Diagnostic Center, University of Kentucky, 1429 Newtown Pike, Lexington, KY 40511 (USA).

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Mammary carcinoma with peritoneal metastasis in a cow.

Vet Patho129:552-553 (1992) Mammary Carcinoma with Peritoneal Metastasis in a Cow M. B. PETRITES-MURPHY Key words: Carcinoma; cattle; mammary glan...
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