Surgical removal of a choroid plexus oncocytoma in an adult cat

An 11‐year‐old male castrated domestic shorthair cat presented with left central vestibular dysfunction. Magnetic resonance imaging of the brain revealed a large, extra‐parenchymal, strongly contrast‐enhancing mass at the level of the left cerebellopontine angle and compressing the cerebellum and brainstem. The mass was surgically excised via left rostral and sub‐tentorial craniectomies and histopathology revealed an epithelial neoplasm composed of anastomosing cords of neoplastic cells that contained large amounts of finely granular hypereosinophilic cytoplasm and round nuclei. The cytoplasmic granules were variably positive with periodic acid‐Schiff and modified Gomori trichrome. Immunohistochemical staining with anti‐cytokeratin AE1/AE3 was diffusely positive. Electron microscopy revealed neoplastic cells that were full of electron‐dense organelles consistent with mitochondria. This is the first case of a choroid plexus oncocytoma in the central nervous system of any domestic animal species and highlights the role of successful surgical intervention in extra‐parenchymal neoplasia in the central nervous system.     

Renal Cystic Adenocarcinoma in a Flowerhorn Cichlid with Metastatic Involvement of the Spleen

Abstract

A 480-g flowerhorn cichlid (an ornamental hybrid) with severe bilateral abdominal swelling, bulla-like structures on the skin, bilateral exophthalmia, and a prolapsed intestine was presented. Radiographs showed compression of the posterior part of the swim bladder and abdominal distention. Ultrasonography of visceral organs revealed a heterogeneous mass with hypoechoic to anechoic polycystic parenchyma and free fluid in the abdominal cavity. At necropsy, free fluid in the abdominal cavity and a large polycystic mass originating from the posterior kidney were observed. Histologically, the mass was composed of more cystic growth of tubules. The renal architecture was replaced by tubules, often irregular in shape, lined by simple to lightly stratified layers of neoplastic and pleomorphic cuboidal to columnar epithelial cells and the absence of glomeruli. Birefringent crystals were observed with polarized light within the lumen of some tubules. The apical border of the neoplastic cells was periodic acid–Schiff positive. Immunohistochemically, the neoplastic cells were positive for cytokeratin AE1/AE3 and proliferating cell nuclear antigen and were negative for p53 (tumor suppressor protein). Microscopic metastasis was seen in the spleen. The metastatic tumor was classified as a cystic adenocarcinoma of the kidney, originating from the proximal tubules.

Received October 7, 2016; accepted June 18, 2017 Published online July 31, 2017     

Atypical fibrosarcoma in the skin of a Roborovski hamster (Phodopus roborovskii)

A 2.5‐year‐old intact male Roborovski hamster (Phodopus roborovskii) was presented with a large subcutaneous mass overlying the abdomen, affecting the animal's ambulation and access to different compartments of the cage through narrow tubing. Ultrasound examination delineated a well‐circumscribed mass in the subcutis of the caudoventral abdominal region. The mass was surgically excised and on cytologic examination showed, in a background of blood, a small population of individually arranged oval to spindle‐shaped cells that exhibited a moderate degree of anisokaryosis, coarsely stippled chromatin, one or more prominent nucleoli, and lightly basophilic well‐defined cytoplasmic processes. Histologically, the mass was composed of interlacing streams and bundles of pleomorphic spindle cells (ganglion‐like cells) with variable amounts of collagenous stroma. The neoplastic cells exhibited moderate features of malignancy. These cells stained intensely with vimentin, but not with any other markers, including antibodies to cytokeratin AE1/AE3, S100 protein, desmin, smooth muscle actin, synaptophysin, neurofilament, and androgen receptor. Based on histologic features, the mass was diagnosed as an atypical fibrosarcoma. This is the first report of an atypical fibrosarcoma in a Roborovski hamster and one of few reports of atypical fibrosarcoma in domesticated hamsters overall.     

Bilateral ovarian adenocarcinoma in a mare causing haemoperitoneum and colic

Abstract

CASE HISTORY: A 13-year-old Thoroughbred mare was presented with a history of mild colic over 3 days. This colic had acutely exacerbated and was unresponsive to analgesic treatment, and was referred to Massey University Veterinary Teaching Hospital.

CLINICAL FINDINGS: On examination the heart rate was 100 beats per minute, and mucous membranes were pale and tacky. A large mass was detected on transrectal palpation in the caudal abdomen to the left of midline. Explorative laparotomy revealed severe haemoperitoneum and several masses that were associated with the reproductive tract. The mare was then subject to euthanasia. On post-mortem examination, adjacent and attached to each ovary were soft, lobulated dark red masses up to 200 mm in diameter. Similar masses were present in the omentum and on the peritoneal surface of the diaphragm and the serosa of the spleen and liver. Histopathology revealed that the neoplastic component of the masses comprised proliferating cuboidal to columnar cells forming disorganised acini and cords separated by dense collagenous stroma. Immunohistochemistry showed the neoplastic cells were positive for cytokeratin AE1/AE3 and vimentin, but negative for cytokeratin 7 and inhibin α.

DIAGNOSIS: Bilateral ovarian adenocarcinoma with transcoelomic metastasis and terminal decompensation due to rupture of a neoplastic mass and consequent haemoperitoneum.

CLINICAL RELEVANCE: To the authors' knowledge, bilateral ovarian adenocarcinoma has not been previously reported in a horse. Ovarian adenocarcinoma should be considered when horses present with haemoperitoneum and colic. Further research is required on the immunohistochemical differentiation of adenocarcinoma of ovarian and intestinal origin in the horse.     

Colonic adenocarcinoma with osseous metaplasia in a horse

Rectal palpation of a 30-year-old mixed-breed mare with chronic weight loss and intermittent, refractory abdominal pain revealed a mass in the right caudoventral portion of the abdomen. Hematologic and serum biochemical findings were normal except for slight mature neutrophilia and mildly high alkaline phosphatase activity and total bilirubin concentration. Cytologic examination of a specimen obtained by abdominocentesis revealed equal numbers of nondegenerative neutrophils and macrophages, but no evidence of neoplastic cells. The mare continued to have signs of abdominal discomfort and was euthanatized. Necropsy revealed a large mass at the junction of the right dorsal colon and transverse colon, and several smaller masses in the liver. Histologic characteristics of the small-colon mass were consistent with colonic adenocarcinoma with osseous metaplasia.     

Invasive ductal carcinoma of the mammary gland in a mare

A 21-year-old thoroughbred mare had a 35 x 14 x 10 cm mass involving the mammary gland. Metastases were found in the kidneys, lungs, skeletal muscles, and regional lymph nodes. Histopathologic examination of the tumor revealed a ductal solid carcinoma with extensive intraductal and intralobular involvement and focal infiltration of the adjacent stroma. The intralobular neoplasms were divided into irregularly shaped islands and sheets of polygonal and spindle-shaped epithelial cells by thick or thin fibrous connective tissue bundles. The neoplastic cells had a small or moderate amount of cytoplasm that stained faintly with eosin and round or oval hyperchromatic nuclei. Immunohistochemically, the neoplastic cells were strongly positive for Lu-5, weakly positive for AE1/AE3, vimentin, and glial fibrillary acidic protein, and negative for cytokeratin 8, cytokeratin 14, alpha-smooth muscle actin, calponin, and S100. The neoplasm was diagnosed as an invasive ductal carcinoma of the mammary gland with multiple metastases.     

A case of canine apocrine sweat gland adenoma, clear cell variant

A cutaneous mass at the base of the retroauricular region of a 4-year-old, female Golden Retriever was examined pathologically. Histologically, the mass formed multiple nodules consisting of a proliferation of large clear cells with abundant cytoplasm. Mitotic figures among the neoplastic cells were very sparse. The large clear cells were intensely positive for cytokeratins (AE1/AE4, cytokeratin 8 and 18) and moderately positive for lysozyme and contained periodic acid-Schiff-positive granules in the cytoplasm. In addition, small flat cells lined the islands of neoplastic large clear cells, and these were strongly positive for alpha-smooth muscle actin and vimentin, and some were positive for cytokeratin (AE1/AE4), suggesting they were myoepithelial cells. No local recurrence or metastasis has been recognized during the 18 months since surgical excision. On the basis of these findings, the present tumor was diagnosed as apocrine sweat gland adenoma, clear cell variant. There have been few previous reports of canine apocrine adenomas showing a clear cell morphology.     

Feline cutaneous and visceral necrotizing panniculitis and steatitis associated with a pancreatic tumour

The association of pancreatic disorders with fat necrosis in domestic animals is rare. This report concerns a case of cutaneous/subcutaneous necrotizing panniculitis and steatitis associated with a pancreatic adenocarcinoma in an 11-year-old male Siamese cat. Clinical investigation revealed variably sized nodules on the trunk, limbs and abdomen. Some of them were ulcerated; others showed a shiny yellow necrotic background featuring irregular sinus tracts. The cat was euthanized at the owner's request before a diagnosis could be made. At necropsy, abundant oily material resembling mustard replaced the subcutaneous tissue and small yellow nodules were disseminated in the omentum, mesentery and serosa of the abdomen. A multilobulated mass arising from the anterior pancreatic head was found along with liver and lymph node metastasis. Histopathology showed wide fistulous tracts draining necrotic fat from the subcutis toward the surface and multifocal areas of necrotic adipocytes replacing the panniculus. Duct-like structures and tubules lined by neoplastic epithelial cells were observed in the primary pancreatic tumour and in the metastatic sites. The aetiology of the fat necrosis was possibly the result of systemic release of lipolytic pancreatic enzymes.     

IMAGING FINDINGS IN PANCREATIC NEOPLASIA AND NODULAR HYPERPLASIA IN 19 CATS

Pancreatic neoplasia in cats is rare and associated with a poor prognosis, but pancreatic nodular hyperplasia is a common incidental finding. The purpose of this study was to describe radiographic and ultrasonographic findings in cats with pancreatic neoplasia or nodular hyperplasia. Fourteen cats (age 3-18 years) were diagnosed with malignant pancreatic tumors: carcinoma/adenocarcinoma (n = 11), lymphoma (n = 1), squamous cell carcinoma (n = 1), and lymphangiosarcoma (n = 1). The most common radiographic findings were an abdominal mass or mass effect (6/6) and lack of serosal margin detail (4/6). On ultrasound, the most common finding was a focal pancreatic mass or nodule, with a size range from 0.4 cm to more than 7.0 cm (8/14). Lymphadenopathy (7/14) and abdominal effusion (7/14) were frequently seen. Five cats (age 10-16 years) with adenomatous/nodular hyperplasia had an abdominal mass or mass effect as the most common radiographic finding (3/3). On ultrasound, all cats had multiple hypoechoic nodules between 0.3 and 1.0 cm associated with the pancreas. Other common findings were pancreatic thickening (2/5), lymphadenopathy (2/5), and abdominal effusion (2/5). The only imaging finding unique to malignant pancreatic tumors was the presence of a single pancreatic nodule or mass exceeding 2cm in at least one dimension (4/14). Although there was a tendency for neoplastic lesions to manifest as single larger lesions and for nodular hyperplasia to manifest as multiple smaller lesions, there was overlap of the imaging findings in both entities. Radiographs and ultrasound can complement but not replace cytology and histopathology in the diagnosis of feline pancreatic neoplasia.     

Systemic mastocytosis with subcutaneous hemorrhage and edema in a Greyhound dog: case report and review of diagnostic criteria

Systemic mastocytosis, characterized by infiltration of multiple organs by neoplastic mast cells, is a well-described entity in human medicine with specific criteria for diagnosis, but is ill defined in veterinary literature. Hemostatic disorders are reported in humans affected by systemic mastocytosis but have not been well described in veterinary literature. A 5-y-old, spayed female Greyhound dog had a 1-mo history of progressive ventral cutaneous edema, hemorrhage, and pain. Cytology of an antemortem aspirate from the subcutis of the ventral abdomen was suggestive of mast cell neoplasia, but no discrete mass was present. The dog was euthanized and submitted for autopsy; marked subcutaneous edema and hemorrhage were confirmed. The ventral abdominal panniculus and dermis superficial to the panniculus carnosus were infiltrated by a dense sheet of neoplastic mast cells. The neoplastic cells contained toluidine blue–positive granules and formed aggregates within the bone marrow and several visceral organs, including the liver, spleen, heart, and kidney. Diffuse edema and hemorrhage is an unusual presentation of mast cell tumors in dogs. Antemortem tests, including complete blood count, coagulation profile, and viscoelastic coagulation testing, were suggestive of a primary hemostatic defect. We discuss here the diagnostic criteria used in humans, how these can be applied to veterinary patients, and the limitations of the current diagnostic framework.     

Papillary renal adenoma of distal nephron differentiation in a horse

A 20-year-old thoroughbred mare had a mass in the right kidney. The mass was encapsulated with fibrous capsule and composed of variably-sized papillary projections lined by a single layer of flattened to cuboidal neoplastic epithelial cells with no cytological and nuclear atypia. Immunohistochemically, the neoplastic cells were broadly positive for cytokeratin AE1/AE3 and granular staining for alpha-1-antitrypsin was focally detected; this immunohistochemical property was similar to that of the normal distal nephron. From these results, this case was diagnosed as papillary renal adenoma of distal nephron differentiation.     

A huge ovarian cyst in a hysterectomized bitch

A 11-year-old, spayed, female mixed breed-dog was presented with an abdominal mass that was detected 1 month ago. Upon abdominal palpation a large, firm, oval shaped, movable mass was found in the mid-abdominal region. Survey radiograph of the abdomen demonstrated an oval soft tissue dense mass located on the right side of the abdominal cavity. A large, heteregenous and cystic mass with solid components occupying the majority of the abdomen and a small, cystic mass with solid components caudal to the left kidney were identified by transabdominal ultrasonography. Computed tomography scans revealed bilateral ovarian masses, and a small volume of retroperitoneal fluid on the right side. A cystic, but otherwise solid mass located in the right ovary and small retained left ovary encapsulated in the ovarian bursa were excised surgically by midline laparotomy. Histopathological examination of the excised mass from the right side revealed a large cystic structure consistent with an ovarian cyst and multiple corpora lutea and follicles at different maturational stages were detected in the left ovary. The precise origin of the ovarian cyst could not be determined by morphological appearance. Immunohistochemical staining suggested a cyst of surface epithelial origin. At re-examination 6 months after the surgery, the bitch appeared healthy and the clinical findings were all normal. To our knowledge, the cyst described here is the largest reported in an incompletely ovariohysterectomized bitch.     

Spontaneous Erythroid Leukemia in a 7-Week-Old Crl:CD (SD) Rat

A young male Crl:CD (SD) rat with erythroid leukemia that presented with emaciation, abdominal distension and a pale visible mucosal membrane was euthanized at 7 weeks of age. At necropsy, enlargement of liver, spleen and pancreatic lymph node was noted. Analysis of blood smear samples revealed many mono- or binucleated erythroblasts that had PAS-positive vacuoles in the cytoplasm. Histopathologically, neoplastic proliferation of atypical cells was observed in the hepatic sinusoids, splenic red pulp, bone marrow, pancreatic lymph node, kidney and lung. Neoplastic cells showed a round to spindle shape, and some neoplastic cells had deeply stained small nuclei and small cytoplasms and resembled erythroblasts. Immunohistochemically, many neoplastic cells were positive for hemoglobin. To our knowledge, this is the first report of erythroid leukemia in a rat of this age. The observed features were similar to those of pure erythroid leukemia in humans.     

Feline cystic thymoma: a clinicopathologic,immunohistologic, and electron microscopic study of 14 cases

Cystic thymoma was diagnosed in 14 cats in a period of 6 years. The most common clinical sign was laboured breathing. The tumours were characterized by various-sized cystic spaces with central vessels. The epithelial cells varied from oval to spindle to polygonal cells enclosing cystic spaces or in pure epithelial cell components. The nuclei of the neoplastic cells had scattered chromatin and small nucleoli. The cytoplasm was pale eosinophilic. The concentration of mature lymphocytes varied from area to area with rare germinal centres. Immunohistochemically, the epithelial cells stained only with AE(1)/AE(3). The central vessels were positive for vimentin, smooth muscle actin, and factor VIII antigen. Electron microscopy revealed that the cyst walls were lined by epithelial cells that were joined by desmosomes, and the walls were well separated from the cystic spaces by a well-defined basement membrane. The neoplastic epithelial cells contained scattered tonofilaments. Three of the cats had metastasis to the lymph nodes and lungs. Two novel cases of ectopic cystic thymoma have also been described. Results of this study reveal that cystic thymoma is uncommon in cats, and that the histomorphologic, immunohistochemical, and electron microscopic features are similar to those of cystic thymoma in humans.     

Three neoplasms in a Eurasian otter (Lutra lutra): malignant melanoma,trichoblastoma and mammary gland adenoma

An eighteen-year-old female Eurasian otter became emaciated and died. Necropsy examination revealed nose and thoracic cutaneous masses, abdominal subcutaneous mass, and multiple nodules in the liver and lungs. Malignant melanoma was found in the nose cutaneous mass and to have metastasized to the liver, lungs, kidneys, adrenal glands, mammary glands and left mandibular lymph node. The neoplastic cells were labeled for vimentin, melanoma, and S100. The cutaneous mass in the thoracic area consisted of spindle shaped neoplastic epithelial cells and was diagnosed as trichoblastoma. Mammary gland adenoma was observed in the abdominal subcutaneous mass. This is the first report of primary three neoplasms of malignant melanoma, trichoblastoma and mammary gland adenoma in a Eurasian otter.     

Feline mesothelioma: case report and review of cytologic,immunocytochemical, histopathologic,and immunohistochemical findings

Mesotheliomas are uncommon neoplasms that arise from mesothelial cells in either the abdominal or thoracic cavities and are rarely diagnosed in cats. A 10-y-old spayed female domestic shorthair cat was presented to the Louisiana State University oncology service for evaluation of a large amount of abdominal effusion. Abdominal ultrasound identified a large mesenteric mass with numerous ill-defined nodules. An abdominocentesis was performed with cytologic and immunocytochemical findings consistent with a neoplastic effusion, with large clusters of epithelioid cells that exhibited strong cytoplasmic expression of pancytokeratin, vimentin, and Wilms tumor 1 antigens. Further testing was declined, and meloxicam was prescribed until the cat died 23 d after initial presentation. Upon postmortem examination, the omentum was contracted into a firm mass adhered to multiple organs and accompanied by numerous small white nodules throughout the abdominal cavity. On histopathology and immunohistochemistry, neoplastic cells were found throughout the abdominal cavity; 60–95% exhibited moderate-to-strong cytoplasmic immunoreactivity for cytokeratin, vimentin, and Wilms tumor 1 protein. The final diagnosis was an epithelioid mesothelioma. Our case illustrates the utility of cytology, immunocytochemistry, and its relation to histology and immunohistochemistry. We also reviewed the reported cases of feline mesothelioma.     

EXTRA-ABDOMINAL CHONDROLIPOMA IN A DOG

A 10-year-old male maltise dog was presented for evaluation of a gradual abdominal enlargement, which had developed over 2 years. (On the radiograph of the abdomen, a significant distention of the abdomen with a large accumulation of fat could be seen.) The mass effect was noticeable because of the rightward displacement of the viscera. There was multifocal amorphous mineralization, mostly in the right abdomen. Computed tomography (CT) identified a 13 x 13 x 10 cm mass, most likely an intra-abdominal lipoma, by which the digestive tract had been displaced in the abdomen. It was only during surgery, however, that the mass was found to be located between the peritoneum and transversus abdominis muscles and the rectus abdominus muscle. It was completely resected. Histopathological examination revealed that the mass was chondrolipoma. The amorphous radiopaque lesion on the images corresponded to cartilaginous tissues with calcification. There has been no recurrence for 10 months. This is the first report of an extra-abdominal chondrolipoma in dogs. Cartilaginous metaplasia of lipoma, located in the abdominal area, should be included in the differential diagnosis for multifocal amorphous mineralization.     

Hydrometra in a ferret-case report.

A desexed female ferret was presented with bilateral alopecic changes. Clinical examination revealed generalized alopecia and abdominal distension. A polycystic mass was found behind the right kidney, and the whole abdomen was filled with a large turgid mass. Radiography and ultrasonography confirmed the presumptive diagnosis of a hydrometra. Hematology and serum biochemistry showed regenerative anemia with light azotemia. Laparotomy showed the presence of a neoplastic mass at the location of the right ovary, a massive enlargement of the uterus filled with a clear fluid, and a subcapsular cyst on the left kidney. After surgery, histopathologic examination of the tissues diagnosed a leiomyoma of the right ovary with hyperplasia of the uterine wall.     

Adenosquamous carcinoma of the oesophagus in a dog

A six‐year‐old mixed‐breed male dog weighing 7.0 kg was presented with chronic vomiting and regurgitation. Endoscopic examination revealed prominent oesophageal dilation in the thoracic region, multiple small greyish‐white nodules over the oesophageal lumen and cauliflower‐like masses in the caudal oesophagus. Histopathological studies revealed a characteristic pattern of coexisting elements of infiltrating adenocarcinoma and squamous cell carcinoma. Immunohistochemical staining with anti‐cytokeratin AE1 + AE3 was positive in both types of neoplastic cells. Neoplastic glandular cells stained positively for cytokeratin 8 while neoplastic squamous cells stained positively for cytokeratin 5/6. On the basis of these findings, the dog was diagnosed with oesophageal adenosquamous carcinoma. The case history and findings suggest that the malignancy might have developed from Barrett's oesophagus following irritation of the oesophageal mucosa due to chronic vomiting and regurgitation.