Mammary Carcinoma in a Mare

Abstract

Mammary tumors are rare in the horse. A 0.11% incidence was quoted among over 40,000 horses from a Paris slaughterhouse [2]. The only case described in detail in the last 50 years was a solid mammary carcinoma that apparently spread hematogenously to produce pulmonary metastases [3].A 19-year-old thoroughbred brood mare recently had an early abortion. The right mammary gland had enlarged over the last four months and was 25 cm long, 10 crn wide and 15 cm thick, 1.5 times as wide and 2.5 times as thick as the left. Overlying skin was intact, with the median raphe deviated to the left anteriorly by part of the right gland that formed a central conical protruberance 6 cm in diameter and 2 cm high. Many clearly demarcated, 2-to 6-cm nodules of firm cream-pink or cream tissue that bulged when clit ( fig. 1) were scattered in the pink parenchyma of the right gland. The median suspensory ligament disappeared into the central protruding nodule. The left gland was pink-brown and finely nodular.The left supramammary and external iliac lymph nodes were slightly enlarged and edematous. The right supramammary group was approximately twice the size of the left, while the right external iliac group was approximately nine times the size of the left. Both these groups on the right side were edematous and each had individual nodes that were firm and creampink. No metastases were seen elsewhere in the abdomen or in the thorax. Cervical vertebrae were cut longitudinally, and no metastases were seen.Histologically, the tumor was a solid carcinoma composed of cells with a round vesicular nucleus and one or two nucleoli. The nuclei varied somewhat in size. Cytoplasm was moderate in amount and vacuolated to various degrees, and cell membranes were poorly defined. There were approximately five mitotic figures per high power field. A large amount of fibrous tissue arranged in trabeculae divided the tumor into large lobules, solid tubules or small groups of epithelial cells. Often these epithelial units had central necrosis and caseation ( fig. 2). Sometimes the epithelium adjacent to this central caseated area was flattened, and suggested lumen formation. The fibrous tissue was heavily infiltrated by plasma cells and fewer lymphocytes and macrophages. In some areas many multinucleate giant cells were associated with the fibrous tissue ( fig. 3). Tumor cells were seen in a few lymphatic vessels. Metastases in the right supramammary and right external iliac lymph nodes resembled the primary tumor. The corresponding nodes on the left were edematous and reactive. No metastases were found at histological examination of large intestine, kidney, adrenal, ovary, heart, lung, liver or inguinal, internal iliac, sublumbar, and mediastinal lymph nodes. The left mammary gland was normal.This tumor has similarities to the only other equine mammary tumor described in detail recently [3]. Both were solid carcinomas, and both had extensive fibrosis with lymphocytic infiltrates. The other tumor, however, apparently metastasized hematogenously and extensiv...

Invasive micropapillary carcinoma of the mammary glands in a mare

“…This report described the clinical, pathological, and immunophenotypical characteristics of invasive micropapillary carcinoma of the mammary glands of an intact mare. Equine mammary carcinomas consist of solid carcinomas (Schmahl 1972;Acland and Gillette 1982;Munson 1987), papillary ductal adenocarcinomas (Foreman 1990;Reppas et al 1996;Prendergast et al 1999), and ductal carcinomas (Hirayama et al 2003). Histopathological findings in this report correspond to the IMC in humans, dogs, and cats.…”

“…Neoplasms of the mammary glands are common in carnivores but are very uncommon in herbivores (Moulton 1990). In horses, there are only a few reports of mammary neoplasms in the last 30 years (Schmahl 1972;Acland and Gillette 1982;Munson 1987;Foreman et al 1990;Seahorn 1992;Reppas et al 1996;Kato et al 1998;Prendergast et al 1999;Hirayama et al 2003;Brito et al 2008). Invasive micropapillary carcinoma (IMC) of the breast is an aggressive and distinctive variant of human infiltrative ductal carcinoma, which presents lymph tropism and frequently spreads to the lymph nodes (Luna-moreé t al.…”

Malignant fibrous histiocytoma of the mammary gland in a mare

“…Mammary tumours are uncommon in mares. Previously reported mammary tumours in mares include 16 cases of mammary carcinoma, adenocarcinoma or adenoma (Schmahl 1972;Acland and Gillette 1982;Munson 1987;Foreman et al 1990;Seahorn et al 1992;Reppas et al 1996;Kato et al 1998;Prendergast et al 1999;Hirayama et al 2003;Sparadi et al 2008). To our knowledge, there have been no prior reports of mammary sarcoma in mares.…”

Internal neoplasia in the horse with special regard to the cytology of body cavity fluid

“…Beschrieben sind unter anderen Adenokarzinome ausgehend von Ovar (Morris et al 1985), Magen (Patton et al 2006), Dünndarm (Honnas et al 1987, Darm (Fulton et al 1990), Pankreas (Church et al 1987), Niere und Euter (Acland and Gillette 1982). Die Inzidenz unter den Neoplasien ist nicht bekannt.…”