Case 180810-1

Seven-year-old, male, castrated standard poodle.

The patient had a two month history of anorexia, vomiting, weight loos, and lethargy. On presentation, the patient was febrile (103.1), lethargic to obtunded, and had pale and tacky mucous membranes. Complete blood count showed nonregenerative anemia and thrombocytopenia. He was found to have marked splenomegaly on abdominal palpation and ultrasound. Ultrasound also revealed enlarged mesenteric, medial iliac, hypogastric, and peri-aortic lymphadenomegaly. Bone marrow aspirates contained atypical epithelial cells, raising suspicion of metastatic carcinoma causing bone marrow suppression. The patient was euthanized due to poor prognosis.

A 24 kg, 7-year old male castrated poodle wass necropsied approximately 23 hours postmortem. The body was in good postmortem condition and contained minimal subcutaneous and visceral adipose stores.

The abdomen contained approximately 100 mls of red-tinged, transparent, watery fluid. The spleen was markedly enlarged, and weighed 0.69 kg (2.9% of body weight). The parenchyma was firm and mostly pale red with one dark red region at the splenic head. There was a poorly-demarcated 7.0 x 4.0 cm region of pylorus, which was approximately 2.0 cm thick. On cut section the wall was firm and white. The overlying mucosa contained a 1.0 cm diameter ulceration. The serosal surface had fibrous adhesions to the diaphragm and mesenteric fat. The vasculature of the greater vessels were dilated. Lymph nodes in the region of the pylorus (gastric and pancreaticoduodenal) were enlarged, between 0.5 and 1.5 cm in diameter, and were firm, white, with effaced architecture. The tracheobronchial lymph node was 0.5 x 0.5 x 1.0 cm and on cut section, the center was mottled dark red to white. The liver weighs 0.86 kg (3.6% of body weight) and is diffusely mottled tan to red and has an enhanced reticular pattern.

Three section of spleen are examined, in which the splenic architecture is largely effaced and disrupted by a densely cellular, poorly demarcated, multinodular, infiltrative, unencapsulated neoplasm composed of variably-sized islands, tubules, and acini formed by polygonal neoplastic epithelial cells. Individual cells have distinct cell borders and moderate amounts of eosinophilic to vesiculated or vacuolated cytoplasm. Nuclei are round to ovoid with coarsely stippled chromatin and one to four prominent nucleoli. Anisocytosis and anisokaryosis are marked and there are two mitotic figures per ten 400x fields. Tubules occasionally contain pale basophilic to eosinophilic secretory product and/or sloughed cells and karryorectic debris. Multifocally, islands appear surrounded by fine fibrous material admixed with fibroblasts. The tissue is infiltrated by large numbers of lymphocytes, plasma cells, and smaller numbers of pigment laden histiocytes, and there are small, scattered accumulations of mixed hematopoietic elements (extramedullary hematopoiesis.

None.

Stomach (pylorus): Gastric adenocarcinoma Lungs, spleen, liver, lymph nodes, bone marrow: metastatic gastric adenocarcinoma.

Metastatic gastric adenocarcinoma was present, and in most cases effacing, all examined lymph nodes, throughout the lung vasculature, liver parenchyma, and diffusely throughout the splenic parenchyma. A bone marrow section taken from the right humerus was completely replaced by metastatic neoplastic cells. Based on the presence of mucin within many of the neoplastic cells, this was presumed to be originating from the gastric epithelium, and was diagnosed as a gastric adenocarcinoma originating within the pylorus.

Metastasis to the spleen is uncommon because it has only efferent lymphatics, and no afferent lymphatics. Metastatic cells must therefore travel to the spleen via arterial blood or implantation.

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