Kilovoltage radiotherapy for companion animals: dosimetric comparison of 300 kV, 450 kV, and 6 MV X-ray beams

Radiotherapy for the treatment of cancer in companion animals is currently administered by using megavoltage X-ray machines. Because these machines are expensive, most animal hospitals do not perform radiotherapy. This study evaluated the ability of relatively inexpensive kilovoltage X-ray machines to treat companion animals. A simulation study based on a commercial treatment-planning system was performed for tumors of the brain (non-infectious meningoencephalitis), nasal cavity (malignant nasal tumors), forefoot (malignant muscular tumors), and abdomen (malignant intestinal tumors). The results of kilovoltage (300 kV and 450 kV) and megavoltage (6 MV) X-ray beams were compared. Whereas the 300 kV and 6 MV X-ray beams provided optimal radiation dose homogeneity and conformity, respectively, for brain tumors, the 6 MV X-rays provided optimal homogeneity and radiation conformity for nasal cavity, forefoot, and abdominal tumors. Although megavoltage X-ray beams provided better radiation dose distribution in most treated animals, the differences between megavoltage and kilovoltage X-ray beams were relatively small. The similar therapeutic effects of the kilovoltage and 6 MV X-ray beams suggest that kilovoltage X-ray beams may be effective alternatives to megavoltage X-ray beams in treating cancers in companion animals.

[Multiple choristoma and a myelolipoma in a Sheltie]

An 11-year-old female Sheltie was presented with inappetence and a progressive increase in abdominal distention. Abdominal ultrasound revealed a large cystic mass in the midabdomen and cystic lesions in the right liver lobe and in the caudal pole of the left kidney. Histopathologic examination of the resected tissue revealed a myelolipoma of the spleen, dispersed splenic tissue in the liver and dispersed uterine and salpinx tissues in the kidney. This report describes the clinical, ultrasonographic and computed tomographic features and the results of histopathology. In addition to the abnormally large and cystic myelolipoma of the spleen, the great number of choristomas is remarkable, which has not previously been documented in a dog.

Spontaneous Eosinophilic Granulated Round Cell Tumors in Rats

Morphologic and histochemical characteristics were noted for three spontaneous tumors with eosinophilic cytoplasmic granules that occurred in aged Fischer 344 rats. Macroscopic lesions were widely distributed in the body, mainly involving the intra-abdominal adipose tissue, pancreas, and mesenterium. These lesions were generally hard swellings with nodular and sclerosing areas. Bloody ascites was a concomitant finding. Histologically, the tumor cells were round, from 9 to 30 μm in diameter with one or two round to oval nuclei, and characterized by eosinophilic granules (0.5–2.0 μm) that stained definitely to weakly positive with the periodic acid-Schiff reaction and demonstrated no metachromasia with toluidine blue stain. Furthermore, the granules were characterized by a positive reaction with lectin histochemistry for concanavalin A (Con A), wheat germ agglutinin (WGA), phaseolus vulgaris agglutinin (PHA-E4), lens culinaris agglutinin (LCA), and recinus communis agglutinin (RCA-I) in all tumors and for ulex europaeus agglutinin (UEA-I), peanut agglutinin (PNA), and soybean agglutinin (SBA) in one tumor. Positive reactions for anti-rat mast cell protease II and CD8 were not demonstrated immunohistochemically. Abundant glycogen was noted in the large tumor cells from one rat. With electron microscopy, the cytoplasmic granules were identified as electron-dense homogenous bodies bounded by a single unit membrane. These characteristics are similar to those of granulated metrial gland cells, but further study is needed to clarify the cell of origin for these tumors.

Round Cell Variant of Myxoid Liposarcoma in a Japanese Macaque (Macaca fuscata)

A 5-year-old, female, Japanese Macaque ( Macaca fuscata) was diagnosed with round cell variant of myxoid liposarcoma. At necropsy, multifocal to coalescing, reddish tan to white nodules, ranging from 0.5 to 1 cm in diameter, were noted throughout the omentum and retroperitoneum. Similar neoplastic nodules were also present in diaphragm, abdominal wall, and on hepatic capsule. Microscopically, neoplastic masses consisted of round to polyhedral cells, which had round, often eccentric nuclei and abundant eosinophilic granular and microvacuolated cytoplasm; Oil red O staining demonstrated large numbers of lipid droplets in the cytoplasm. Ultrastructurally, the cytoplasm of the tumor cells was packed with occasional lipid vacuoles and numerous enlarged mitochondria. Immunohistochemistry revealed tumor cells were positive for vimentin, while negative to cytokeratin, actin, and Factor VIII-related antigen. To the authors' knowledge, this is the first report of round-cell variant of myxoid liposarcoma in nonhuman primate.

Collagenoma in an African Clawed Frog (Xenopus laevis)

A 3-y-old female Xenopus laevis was reported for a gray mass on the abdomen. The frog was used for egg collection and was otherwise experimentally naïve. On physical exam, the frog was bright and active and had a firm, gray, lobulated mass (1.5 cm × 0.5 cm × 0.5 cm) in the cutaneous tissue of the left lateral abdomen. An excisional biopsy was performed under anesthesia, and the entire mass was removed and processed for histopathology. Microscopically, the dermis was greatly expanded by connective tissue with a marked decrease in the number of glands, and occasional degenerative glands were present. When stained with Masson trichrome, the excessive connective tissue stained blue, indicating that it was composed of collagen. With Verhoeff-van Gieson staining, the connective tissue stained bright red with an absence of black-staining material, demonstrating the presence of collagen and ruling out elastic fibers. In light of the morphology of the mass and the results of the special stains, the mass was diagnosed as a collagenoma. To our knowledge, this report is the first description of a collagenoma in X. laevis.

[Haemoabdomen and haemothorax in a cow with metastatic granulosa cell tumor]

This case report describes the clinical, ultrasonographic, pathological and histological findings in a two-year-old Swiss Braunvieh cow with granulosa cell tumor and metastases in the abdomen and thorax. The cow was ill and had tachycardia, coughing, increased breath sounds, positive reticular foreign body tests and a tense abdominal wall. Ultrasonography revealed a massive accumulation of hypoechoic fluid in the thorax and abdomen, and abdomino- and thoracocentesis yielded red fluid indicative of abdominal and thoracic haemorrhage. Because of a poor prognosis, the cow was euthanized and examined postmortem. Multiple nodular lesions were seen in the omentum, liver, spleen and lungs. The left ovary was grossly enlarged and nodular in appearance. Histological examination of the lesions revealed granulosa cell tumour of the left ovary and metastases in the omentum, liver, spleen and lungs.

[Diagnostic assessment of peritoneal fluid cytology in horses with abdominal neoplasia]

OBJECTIVE

To evaluate the diagnostic value of peritoneal fluid (PF) cytology for clinical diagnosis of abdominal neoplasia in horses.

MATERIAL AND METHODS

Ten horses with histopathologically confirmed abdominal neoplasia, in which a PF analysis was performed, were included in this retrospective study. PF was analyzed for total protein concentration and a nucleated cell count was performed. Using cytological criteria of malignancy, the PF samples were evaluated regarding their probability of malignancy.

RESULTS

Cytologic classification of cells according to criteria of malignancy allowed a positive cytologic diagnosis of neoplasia in 5 out of 10 peritoneal fluid samples. Malignant lymphoma was the most commonly diagnosed neoplasia (3/10) and could be identified by cytology in 2/3 cases. In 1/2 horses with plasma cell myeloma neoplastic cells were similarly found. Malignant melanoma (2/10) was diagnosed using cytology in one case (presence of melanin-containing cells). Cytological diagnosis of malignant neoplasia was established in the only horse with gastric squamous cell carcinoma, but the morphology of the identified tumour cells did not allow a specific diagnosis. Thus, a definitive diagnosis was achieved in 4/5 horses with proven abdominal neoplasia. The horses with adenocarcinoma (1/10) and haemangiosarcoma (1/10) had no evidence of neoplasia based on cytological findings. No relationship between total protein concentration or the nucleated cell count with the histolopathological diagnosis of abdominal neoplasia was found. Abnormal mitotic figures were considered of greater diagnostic value than the overall mitotic rate.

CONCLUSION

The implementation of nuclear criteria of malignancy in the cytologic evaluation of PF samples allows the identification of neoplastic cells to an acceptable degree. For this purpose, the knowledge of the highly variable morphological features of mesothelial cells is essential. The absence of malignant cells does not rule out abdominal neoplasia.

CLINICAL RELEVANCE

PF cytology should be considered as a valuable, minimally invasive, simple, and rapid diagnostic technique in horses with suspected abdominal neoplasia.

Uterine adenocarcinoma with abdominal metastases in an ovariohysterectomised cat

SURGICAL FINDINGS: an adenocarcinoma of the uterine stump with abdominal metastases is described in a 12.5-year-old incompletely ovariohysterectomised domestic shorthair cat. At the time of presentation, the adenocarcinoma had metastasised to the right perirenal lymph node, the abdominal aorta and the right ureter, resulting in the formation of a large cystic structure. This had compressed and displaced surrounding structures, including the abdominal vena cava and the right kidney, and formed multiple adhesions to the body wall and adjacent abdominal structures. Metastatic extension to the aorta had resulted in its regression into a 2 mm diameter non-pulsatile vessel.

PRACTICAL RELEVANCE

only one case of uterine adenocarcinoma has previously been reported in an ovariohysterectomised cat. As such, this represents a very unusual and severe complication following an incomplete ovariohysterectomy. Invasion of the tumour tissue into surrounding structures created further complications.

Malignant peripheral nerve sheath tumour (malignant schwannoma) in the diaphragm of a goat

This report describes a malignant schwannoma in the diaphragm of a 2-year-old goat. The immunohistochemical and histological features indicated a diagnosis of malignant schwannoma rather than neurofibrosarcoma. The diaphragm represents an unusual location for neoplasia in both domestic animals and human beings. A possible anatomical origin from the phrenic nerve is discussed.

B-cell lymphoma in a dog with ehrlichiosis (Ehrlichia canis) and systemic histoplasmosis (Histoplasma capsulatum)

A mixed breed dog treated for ehrlichiosis and systemic histoplasmosis developed a refractory thrombocytopenia. When an abdominal mass was detected, exploratory laparotomy and biopsies confirmed lymphoma, which on immunohistochemical stains was determined to be of B-cell origin. Conceivably, the B-cell lymphoma in this dog was associated with chronic inflammation from ehrlichiosis, histoplasmosis, or both.

Nephroblastoma with transcoelomic metastasis in a Japanese black bull

This paper describes a nephroblastoma with transcoelomic metastasis in a three-year-old Japanese black bull. At necropsy, a huge, oval neoplastic mass containing the residual right kidney was found. Moreover, severe transcoelomic metastasis occurred throughout the abdominal and thoracic cavities. Histologically, the mass was mainly composed of sheets, nests, islands and cords of polygonal blastemal cells with trabeculae of fibrous stroma. In some areas, epithelial elements composed of tubules and winding duct-like structures were also observed. Glomeruloid structures were scattered in these epithelial elements. Metastatic nodules were composed of blastemal and stromal elements, which were similar to those in the mass.

Comparison of lipase activity in peritoneal fluid of dogs with different pathologies--a complementary diagnostic tool in acute pancreatitis?

A clinical diagnosis of acute pancreatitis is often difficult to obtain. Histopathology remains the gold standard, whereas clinical signs, diagnostic imaging and laboratory testing, even in combination, may be insufficient. In a prospective study, lipase activity in ascitic fluid of various aetiologies was determined in 44 dogs in order to investigate its performance in cases of acute pancreatitis. Data of simultaneously determined blood lipase activities were available in 27 dogs. Lipase activity was measured by a colorimetric assay. A complete peritoneal fluid analysis was performed. Dogs were divided into four groups, according to their final diagnosis: acute pancreatitis (A), abdominal trauma (B), abdominal neoplasia (C) and others (hepatic or cardiac diseases) (D). Dogs with acute pancreatitis had a significantly higher peritoneal lipase activity than those in other groups (P < or = 0.024), while no significant difference was found between the other groups (P > or = 0.734). Blood lipase activity as well as protein content and total cell count of the ascitic fluid did not show any significant difference between groups. Data show that determination of lipase activity in dogs that develop ascites may be useful in complementing the diagnosis of acute pancreatitis.

Subcutaneous Angiolipoma of Abdomen in a Golden Hamster (Mesocrietus auratus)

This is a single case report of an angiolipoma located in the subcutis of a 2-year-old golden hamster. The histological appearance of the tumour resembled that described in other species. The hamster died 1 month following removal of tumour and a necropsy was not performed. This is apparently the first recorded case of angiolipoma in a hamster.

Metastasis of gastric adenocarcinoma to the abdominal wall following placement of a gastrostomy tube in a dog

Stoma site metastasis of gastric adenocarcinoma was documented 37 d after partial gastrectomy with gastrostomy tube placement, and 22 d after tube removal. The tube was placed through grossly normal tissue but histopathologic examination revealed neoplasia at the surgical margins and concurrent lymphatic metastasis. Stoma site metastases may be due to direct tumor seeding or hemolymphatic spread.

Hyperadrenocorticism in a dog due to ectopic secretion of adrenocorticotropic hormone

Spontaneous hyperadrenocorticism in dogs is known to be the result of excessive secretion of adrenocorticotropic hormone (ACTH) by the pituitary gland or excessive autonomous glucocorticoid secretion by an adrenocortical tumor. Here, we report on an 8-year-old German shepherd dog in which ACTH-dependent hyperadrenocorticism was a result of ectopic ACTH secretion and could be related to an abdominal neuroendocrine tumor. Hyperadrenocorticism was diagnosed on the basis of the history, clinical signs, and elevated urinary corticoid/creatinine ratios (UCCRs; 236 and 350 x 10(-6); reference range < 10 x 10(-6)). The UCCR remained elevated (226 x 10(-6)) after three oral doses of dexamethasone (0.1 mg/kg body weight) at 8-h intervals. Ultrasonography revealed two equivalently enlarged adrenal glands, consistent with adrenocortical hyperplasia. Plasma ACTH concentration was clearly elevated (159 and 188 ng/l; reference range 5-85 ng/l). Computed tomography (CT) revealed that the pituitary was not enlarged. These findings were interpreted as indicating dexamethasone-resistant pituitary-dependent hyperadrenocorticism. Transsphenoidal hypophysectomy was performed but within 2 weeks after surgery, there was exacerbation of the clinical signs of hyperadrenocorticism. Plasma ACTH concentration (281 ng/l) and UCCRs (1518 and 2176 x 10(-6)) were even higher than before surgery. Histological examination of the pituitary gland revealed no neoplasia. Stimulation of the pituitary with corticotropin-releasing hormone did not affect plasma ACTH and cortisol concentrations. Treatment with trilostane was started and restored normocorticism. CT of the pituitary fossa, 10 months after hypophysectomy, revealed an empty sella. Hence, it was presumed that there was ectopic secretion of ACTH. CT of the abdomen revealed a mass in the region of the pancreas and a few nodules in the liver. Partial pancreatectomy with adjacent lymph node extirpation was performed and the liver nodules were biopsied. Histological examination revealed a metastasized neuroendocrine tumor. Abdominal surgery was not curative and medical treatment with trilostane was continued. At 18 months after the abdominal surgery, the dog is still in good condition. In conclusion, the combination of (1) severe dexamethasone-resistant hyperadrenocorticism with elevated circulating ACTH levels, (2) definitive demonstration of the absence of pituitary neoplasia, and (3) an abdominal neuroendocrine tumor allowed the diagnosis of ectopic ACTH secretion.

A RETROSPECTIVE STUDY ON THE SONOGRAPHIC FINDINGS OF ABDOMINAL CARCINOMATOSIS IN 14 CATS

A retrospective review was performed on 14 cats with histology- or cytology-proven carcinomatosis. The mean age was 12.7 years with a median of 11 years. The diagnosis of carcinomatosis was made by histology in 11 cats and cytology in three cats. Twelve cats had cytologic examination of the peritoneal free fluid and seven cats (58.3%) had evidence of malignant cells. The primary tumor site was determined in 13 cats. The most common organ locations for the primary tumor were the liver (n = 5), pancreas (n = 3), and small intestine (n = 3). Other sites were stomach and spleen in one cat each. Epithelial cell neoplasia was the primary tumor type in 11 cats. Two cats had abdominal lymphomatosis and one cat had abdominal sarcomatosis secondary to metastatic hemangiosarcoma. Free peritoneal fluid and masses in the connecting peritoneum were found in all cats (100%). Additional findings included primary or metastatic masses in abdominal organs in 10 cats (71.4%), lymph node enlargement in five cats (35.7%), pleural effusion in three cats (21.4%), parietal peritoneal masses in two cats (14.3%), and visceral peritoneal masses in one cat (7.1%). Masses in the connecting peritoneal may be a very specific finding for carcinomatosis in cats, especially with a concurrent abdominal neoplastic mass. Parietal and visceral peritoneal masses, while uncommon in this series of cats, have not been reported for other diseases and seem to strongly support a diagnosis of carcinomatosis.

SONOGRAPHIC FEATURES OF HISTIOCYTIC NEOPLASMS IN THE CANINE ABDOMEN

The purpose of this retrospective study was to describe the ultrasonographic features of malignant histiocytosis (MH), malignant fibrous histiocytoma, and histiocytic sarcoma in abdominal organs of dogs. The medical records of 18 dogs that had undergone abdominal sonography and had a histopathologic diagnosis of abdominal MH, malignant fibrous histiocytoma, and histiocytic sarcoma were reviewed. The organ most commonly affected was the spleen. MH was the most common followed by histiocytic sarcoma and malignant fibrous histiocytoma. In the spleen there were often multiple hypoechoic nodules with well-defined borders. In one dog, without focal lesions, the spleen was enlarged and hypoechoic. The liver was the second most commonly affected organ. MH was most common followed by histiocytic sarcomas and malignant fibrous histiocytoma. The most common sonographic feature in the liver was the presence of multiple hypoechoic nodules with well-defined borders. One dog without hepatic nodules had a liver that was ultrasonographically enlarged and hypoechoic. MH in the abdominal lymph nodes resulted in hypoechoic lymphadenopathy. Malignant fibrous histiocytoma was the only neoplastic type in the kidneys appearing as a single heteroechoic renal mass with well-defined borders. MH was observed in the stomach of one dog. Sonographically there was a single well circumscribed hypoechoic mass with well-defined borders and abnormal stomach layers. In this study it was not possible to differentiate between MH, malignant fibrous histiocytoma, and histiocytic sarcoma using sonography.

Management of hemodynamic changes associated with removal of a large abdominal myofibroblastic tumor in a pony

A 22-year-old female Welsh-cross pony was evaluated because of intermittent colic, signs of depression, pyrexia, anorexia, muscle wasting with abdominal distention, and weight gain over the preceding 12 months. A large abdominal mass was detected and surgically removed; the hemodynamic alterations and complications caused by the dramatic fluid losses and shifts that can occur in association with removal of a large abdominal mass required extensive postoperative management. Monitoring of clinical and hematologic variables such as attitude, heart rate, mucous membrane color, mean arterial blood pressure, PCV, and plasma total protein concentration provided useful information for successful management of the patient after surgery. On removal, the tumor weighed 19% of the pony's body weight and was characterized as a myofibroblastic tumor. Myofibroblastic tumors should be considered as a differential for large internal abdominal masses in horses, and surgical removal may be feasible and life extending with appropriate postoperative care.

Tumor selective antivascular effects of the novel antimitotic compound ABT-751: an in vivo rat regional hemodynamic study

Selective induction of vascular damage within a growing tumor is a potentially important approach in the search for potent anticancer therapeutics. Tubulin-binding (antimitotic) agents destabilize cellular microtubules, suppress tumor growth, and exert antivascular effects with varying degrees of tumor selectivity in preclinical models. The tumor-selective, antivascular effects of ABT-751, a novel, orally active antimitotic agent, currently in phase II clinical development, were characterized in vivo in the present study. We developed an in vivo rat model designed to quantify acute changes in regional vascular resistance (VR) in both tumor and non-tumor vascular beds simultaneously. Tissue-isolated tumors (1 g) with blood flow supplied by a single epigastric artery were grown in rats. Subsequently, tumor blood flow was measured under anesthesia in solid tumors and also in mesenteric, renal, and normal epigastric arteries. Phenylephrine-induced (1 micromol/kg) increases in VR were not different between tumor and non-tumor epigastric arteries, suggesting that tumor vessels possess relatively normal vasoconstrictive function. ABT-751 (3, 10, and 30 mg/kg; i.v.) produced modest transient increases in mean arterial pressure with no effect on heart rate. Tumor VR increased to 75+/-36, 732+/-172, and 727+/-125% above baseline, respectively (P<0.05 for the 10 and 30 mg/kg doses), whereas VR in normal epigastric arteries was not significantly affected. Administration of ABT-751 produced transient modest ( P<0.05) increases in mesenteric VR and no effect on renal VR. These results demonstrate that ABT-751 produces marked reductions in tumor blood flow in the intact rat at doses that exert negligible effects on normal vascular function.

Percutaneous fine-needle biopsy of deep thoracic and abdominal masses in dogs and cats

Percutaneous fine-needle biopsy was used to investigate thoracic and abdominal masses in the dog and cat. One hundred and thirty-two cases were included in the study; 20 cases were excluded from the comparative study due to poor cellularity or blood contamination (retrieval rate 86.8 per cent). One hundred samples (56 dogs and 44 cats) were classified by cytology as neoplastic. All the cytological diagnoses of neoplasia were confirmed by histological samples obtained either by non-surgical methods, at surgery or during postmortem examination. No false positive diagnoses of neoplasia were made. Thirty-two samples were cytologically classified as 'negative for neoplasia'. Subsequent histological examination revealed 18 true negative and 14 false negative results. The procedure had an overall 89.4 per cent (118 cases out of 132) agreement between the diagnosis of inflammatory disease versus neoplasia, with a sensitivity of 87.8 per cent, a specificity of 100 per cent, a predictive value of a positive test of 100 per cent and a predictive value of a negative test of 56.3 per cent.

Morphological characterization of skin ganglion-like cells in Djungarian hamsters (Phodopus sungorus)

Characteristic ganglion-like cell proliferation observed in the skin of Djungarian hamsters was investigated using 24 male and 24 female hamsters, 1-6 months of age, to examine the anatomic location of these ganglion-like cells and their morphologic features. One abdominal skin tumor composed of these cells and resembling proliferative fasciitis in humans was also examined. Skin ganglion-like cells were rarely observed in young animals but increased in number and extent with age, especially in males. These cells were frequently seen in the ventral and medial regions of the trunk and legs rather than in the dorsal and lateral regions. Light microscopic examination of these ganglion-like cells revealed abundant vesicular basophilic cytoplasm with delicate intracytoplasmic silver stain-positive fibrils. Ultrastructurally, these cells contained abundant rough endoplasmic reticulum and Golgi complexes with dilated cisternae; intracellular collagen fibrils were present within these cisternae. Heat shock protein 47, beta-tubulin, and androgen receptor were expressed in these cells. The morphologic features of cells of one tumor resembling human proliferative fasciitis were identical to those observed in ganglion-like cells. The results of the present study suggest that these ganglion-like cells are derived from intrinsic undifferentiated mesenchymal cells in the dermis or subcutaneous adipose tissue and that any tumor-like lesion they form should be regarded as an abnormal proliferative lesion of skin ganglion-like cells rather than as proliferative fasciitis or fibroma.

Peripheral neuroblastoma in a newborn piglet

Peripheral neuroblastoma (PNB) is a rare neoplasia derived from neuroepithelial cells. PNB typically presents as a greyish mass, composed of round cells with features of neuronal differentiation. Necropsy, performed on a 1-day-old piglet, revealed a mass craniodorsally located in the abdominal cavity. Histologically, the predominant population consisted of small round to ovoid cells with scanty cytoplasm and dark round nuclei, besides, there were larger neurone-like cells. Neurone-specific enolase and S-100 protein were immunohistochemically detected, while glial fibrillary acidic protein was negative. Histological and immunohistochemical findings substantiated the diagnosis of a grade II peripheral neuroblastoma. This seems to be the first description of a PNB in a newborn piglet.

Experience from a long-term carcinogenicity study with intraperitoneal injection of biosoluble synthetic mineral fibers

The carcinogenic potential in the intraperitoneal cavity of three newly developed biosoluble insulation glass wool fibers (M, P, and V) and one newly developed biosoluble insulation stone wool fiber (O) was investigated and compared to that of a previously developed soluble glass fiber (B). The in vitro dissolution coefficient of the three glass wool fibers ranged from 450 to 1037 ng/cm(2) x h and was 523 ng/cm(2) x h for the stone wool fiber. The in vitro dissolution coefficient of the B fiber was 580 ng/cm(2) x h. Groups of female Wistar rats (strain Crl: Wi BR) were exposed by repeated injections to doses of 0.5, 2, and 5 x 10(9) WHO fibers, which corresponds to between 41 mg to 724 mg fiber injected. In addition, 2 groups of crocidolite were used as positive controls at doses of 0.1 x 10(9) and 1 x 10(9) WHO fibers (0.5 and 5 mg). The in vitro dissolution coefficient of crocidolite is estimated to be approximately 1 ng/cm(2) x h. The protocol of the study and the size distribution of the test samples conformed to the European Commission Protocol EUR 18748 EN, and the study was executed under Good Laboratory Practice conditions. Two of the new insulation wools, fibers M and 0, showed no statistically significant tumorigenic response even at the very high dose of 5 x 10(9) WHO fibers injected. Fibers P and V showed a small tumorigenic response in the ip cavity similar in magnitude to the B fiber, which has been declared in the German fiber regulations as a noncarcinogenic fiber. The response to the soluble insulation fibers was notably different from that of the known carcinogen crocidolite, which produced 53% tumors at a comparatively low dose of 0.1 x 10(9) WHO fibers. The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas. Differences in etiology were observed between the massive doses of the highly soluble insulation wools when injected directly into the ip cavity and the lower doses of the extremely insoluble fiber crocidolite. The variability in this reaction and the impairment of animal health put into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools. All of the fibers tested fulfilled the exoneration criteria with respect to carcinogenicity according to the European Directive 97/69/EC ("an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity"). The dose as defined in the EC-Protocol EUR 18748 EN was 1 x 10(9) WHO fibers with a defined geometric spectrum. The influence of fiber dimensions on the ip tumor response and the difficulty in assessing the influence of the difference in background levels between this and previous studies make direct application of the German TRGS 905 criteria difficult; however, by comparison to fiber B, which in the TRGS 905 is considered as a noncarcinogenic fiber, all of the synthetic mineral fiber types tested in this study also appear to meet the intended German criteria for exoneration.

Body cavity lipomas in six dogs

Histologically confirmed lipomas were surgically removed from the thoracic or abdominal cavities of six dogs. Three dogs had a large intra-abdominal mass causing severe abdominal distension. Two dogs had a mass extending into the pelvic canal, compressing the colon and causing obstipation. One dog with an intrathoracic mass had a history of coughing and intermittent cyanosis. All dogs had complete resolution of signs after surgical resection of the tumour. Recurrence occurred in one dog with an abdominal lipoma, two years after the initial surgery. This recurrent lipoma was treated successfully by surgical resection.

Juvenile malignant mesothelioma in a dog

An 11-month-old male mixed breed dog was euthanized due to two months history of vomiting and anorexia. At necropsy, numerous, multifocal or coalescing, firm, protruding nodules, 5 to 40 mm in diameter were scattered throughout the mesentery and omentum. Histologically and immunohistochemically, the nodules were diagnosed as malignant mesothelioma. Metastasis to the regional mesenteric, mediastinal and tracheobronchial lymph nodes were observed.

Metastatic subcutaneous sarcoma and abdominal carcinoma in a peach-faced lovebird (Agapornis roseicollis)

A 2-year-old male peach-faced lovebird (Agapornis roseicollis) with a subcutaneous sarcoma on the right carpus was treated by surgical amputation. Three months after surgery, lung metastases causing clinical signs of dyspnoea were diagnosed radiographically and subsequently the bird was euthanased. At necropsy, a tumour firmly attached to the right testis, kidney and lung was found, and several tumours were present in the lung parenchyma. Histopathology revealed a mesenchymal growth pattern in the carpal subcutis and lung neoplasms, and an infiltrating epithelial pattern in the abdominal one. Immunohistochemistry for muscle actin, keratin, neurone-specific enolase and chromogranin confirmed the different cell lineage of the neoplasms, thus leading to the diagnosis of a fibrosarcoma in the subcutis with pulmonary metastases, and a carcinoma of indeterminate origin in the cranial abdomen.

Subcutaneous hemangiosarcomas in a rhesus macaque (Macaca mulatta)

Hemangiosarcoma is a malignant tumor of vascular endothelial cell origin. The occurrence of hemangiosarcoma in nonhuman primates has been rarely documented. An adult male rhesus monkey was reported having a firm subcutaneous swelling, approximately 4.5 cm in diameter, on the ventral midline of the abdomen. Fine-needle aspiration, microbial culture, biopsy, radiographs, exploratory laparotomy, histopathology, immunohistochemistry, hematology, and serology were performed. A second subcutaneous mass approximately 4.5 x 4.0 x 2.7 cm developed on the ventral midline several weeks later. A fine-needle aspirate of the first mass consisted of numerous erythrocytes with few polymorphonuclear cells and lymphocytes. Histopathology showed foci of spindle-shaped cells surrounding the vascular spaces. Many spindle-shaped cells had prominent nucleoli, and mitotic figures could occasionally be seen. Immunohistochemical staining of the masses for Factor VIII-related antigen, an endothelial cell and tumor marker, yielded positive results. Both masses were consistent with hemangiosarcoma.

Unusual immunophenotype of a soft tissue sarcoma in a European polecat (Mustela putorius)

The most commonly reported tumors in ferrets are carcinomas, followed by round cell tumors. Soft tissue sarcomas are reported and characterized much less frequently. Because domesticated ferrets (Mustela putorius furo) are direct descendants of European polecats (Mustela putorius), the types and prevalence of tumors are expected to be similar in the two species. Presented here is a case report of unusual immunohistochemical staining characteristics of an abdominal wall leiomyosarcoma in a close relative of domestic ferrets, the European polecat. Sections of tissue were preserved in 10% buffered formalin, embedded in paraffin, and sectioned at 5 mm. Routine staining with hematoxylin and eosin and several immunohistochemical tests were performed to identify the tumor tissue of origin. Although the tumor did not stain with antibody to desmin, further staining for smooth muscle actin was consistent with a smooth muscle origin. To the authors' knowledge, this report is the first description of a leiomyosarcoma in the European polecat. This report emphasizes the importance of using additional secondary markers to accurately diagnose anaplastic tumors.

Peritoneal effusion in a dog secondary to visceral mast cell tumor. A case report

BACKGROUND

Mast cell tumor, one of the most common skin tumors in dogs, may also be found in visceral sites (mainly spleen and liver). When a visceral mast cell tumor is present, neoplastic mast cells may be found in any effusion secondary to the tumor. Therefore, the diagnosis may be made by cytologic analysis of the effusion.

CASE

An 8-year-old, spayed, female Siberian husky presented with a peritoneal effusion secondary to a visceral mast cell tumor. Seven months earlier, the dog had presented with a cutaneous nodule diagnosed as a well-differentiated mast cell tumor. The peritoneal fluid was classified as a transudate. Numerous neoplastic mast cells were found in the effusion. Although the mast cell tumor presented with characteristics of the well-differentiated tumor, its biologic behavior was that of a malignant tumor.

CONCLUSION

Care should be taken to evaluate the prognosis of mast cell tumors in dogs since their biologic behavior is extremely variable.

Transitional cell carcinoma of the urinary bladder in a Thoroughbred, with intra-abdominal dissemination

A 14-year-old Thoroughbred gelding with a history of acute onset of hematuria was presented for necropsy. Transitional cell carcinoma of the urinary bladder with intra-abdominal dissemination was diagnosed. Tumor masses were observed on the splenic capsule and surrounding the distal abdominal aorta. Tumor cells showed diffuse cytoplasmic reactivity for cytokeratin but were negative for epithelial membrane antigen, carcinoembryonic antigen, tumor-associated glycoprotein 72, and vimentin.

Sarcoma of possible nerve sheath origin in a captive muskrat

A captive adult female muskrat (Ondatra zibethicus) was found dead without previous signs of disease. At necropsy, abdominal organs were infiltrated with a poorly demarcated, soft, tan tissue. Microscopically this tissue was composed of neoplastic cells assuming two distinct growth characteristics consistent with Antoni A and B patterns. Ultrastructurally, the neoplastic cells were pleomorphic, lacked junctional devices, had abundant mitochondria and ergastoplasm, and frequently were closely associated with extracellular collagen. Immunocytochemical examination of tumor cells demonstrated sporadic expression of neuron specific enolase. Microscopic tumor metastases to the myocardium, ascending aorta, lungs and visceral pleura were present. This is the first report of a sarcoma compatible with a malignant peripheral nerve sheath tumor in a muskrat.

Unusual metastatic behavior and clinicopathologic findings in eight cats with cutaneous or visceral hemangiosarcoma

Eight cats with visceral or cutaneous hemangiosarcoma were evaluated, and unusual metastatic and clinicopathologic behavior was evident in each. Cutaneous hemangiosarcoma is generally believed to be locally aggressive and slow to metastasize. These 8 cats with cutaneous hemangiosarcoma, however, developed metastatic disease after initial surgical resection; only 1 had local regrowth of the tumor. All cats with visceral hemangiosarcoma had metastasis at the time of diagnosis, which is consistent with cats of other reports. Three of 8 cats had evidence of disseminated intravascular coagulation, including increased prothrombin time and partial thromboplastin time, decreased number of platelets, and anemia. These potential complications need to be considered when planning diagnostic and treatment protocols.

Feline infectious peritonitis presenting as a tumour in the abdominal cavity

This paper describes six cases of feline infectious peritonitis (FIP) in which an abdominal tumour had been suspected clinically. Pathological changes were mainly restricted to the massive enlargement of a mesenteric lymph node due to necrogranulomatous lymphadenitis. FIP was diagnosed on the basis of the immunohistological demonstration of coronavirus antigen in intact macrophages within the necrogranulomatous lesions. In the affected lymph node lymphoid tissue was either almost completely effaced or restricted to follicles composed mainly of variable numbers of blasts. From one to many plasma cells positive for coronavirus-specific antibodies were present in the marginal sinuses or capsules. In addition, necrogranulomas were present in the gut-associated lymphoid tissue of the caecum of one cat, and adjacent to the affected lymph node of another.

Abdominal neoplasia (excluding urogenital tract)

Neoplasia of the equine gastrointestinal tract and abdominal organs occurs predominantly in geriatric horses, although lymphoma and hepatocellular carcinoma and a few other neoplasms can be found in young horses. This article discusses diagnostics that can be used in weight-loss situations, suspicious of neoplasia, as well as tumors themselves including clinical signs, diagnostic tools, histopathologic appearance, and management.

Lymphoid neoplasia in the koala

OBJECTIVE

Correlation of immunophenotype with history, anatomical and morphological features of lymphoid neoplasia in the koala.

METHODS

Routine necropsies were performed on 51 koalas with suspected lymphoid neoplasia between 1986 and 1997 in New South Wales and Queensland. Immunophenotyping was by an immunoperoxidase method utilising species cross-reactive antibodies raised against human lymphocytes and an antibody raised against koala IgG. Cases were classified according to organs and tissues affected and the morphological features of neoplastic cells.

RESULTS

Twenty-six (51%) of the cases were of the T cell immunophenotype, 12 (24%) were of B cell immunophenotype and 13 (25%) did not stain. The age and sex of koalas did not correlate with immunophenotype (P = 0.686 and P = 1.000, respectively). Thirty-two cases were leukaemic and 36 had multiple organ involvement, probably reflecting presentation of koalas at advanced stages of disease. Abdominal tissue involvement was most common (44 cases), followed by nodal (32), atypical (21) and cervicomediastinal (14). The T cell immunophenotype was over-represented among the leukaemic cases (P = 0.013). Generally, the T cell immunophenotype predominated except for many affected atypical tissues. Neoplastic cells were mostly of medium nuclear size with round to oval nuclei. No correlations were found for cell morphology, mitotic index and immunophenotype.

CONCLUSION

The prognostic value of an immunophenotypic, anatomical and morphological basis for the classification of lymphoid neoplasia in the koala currently is limited by the need to detect these neoplasms at an early age, the requirement for freshly fixed tissues and the restricted range of available cross-reacting antibodies.

Surgical removal of an undifferentiated abdominal sarcoma from a koi carp (Cyprinus carpio)

An undifferentiated abdominal sarcoma was removed surgically from a koi carp. The diagnostic procedures, including radiography and computed tomography, and the procedures for general anaesthesia and the surgical approach for a celiotomy in a fish are described. The gross and microscopic appearance of the tumour is described and illustrated.

Peripheral neuroblastoma in a young Beagle dog

A peripheral neuroblastoma was found in the abdominal cavity of a young male beagle dog. The large tumor mass involved the left kidney and both adrenal glands. Histologically, a major portion of the neoplasm consisted of lobulated sheets of small round cells with hyperchromatic nuclei mixed with polygonal cells and neuropil. Small clusters of polygonal cells with abundant eosinophilic cytoplasm and a trabecular growth pattern were observed adjacent to some of the tumor lobules. Small, round neoplastic cells metastasized to lumbar lymph nodes and also to the adrenal glands. The neoplastic cells were positive for neuron-specific enolase, synaptophysin, and neurofilament protein. Electron micrographs revealed intracytoplasmic dense core granules, microtubules, intermediate filaments, and desmosomes in the cytoplasm of the neoplastic cells.

Morphological variations in transplanted tumors developed by inoculation of spontaneous mesothelioma cell lines derived from F344 rats

Morphological and immunohistochemical features of the abdominal mesotheliomas that were developed by inoculation of 3 cell lines (MeET-4, -5 and -6) established from spontaneous abdominal mesotheliomas in male F344 rats. Although the original tumors of three cell lines showed signs of epithelioid growth with a predominantly simple papillary pattern, transplanted tumors revealed a variety of morphologic features including epithelioid with glandular structures, sarcomatous, and a mixture of these components. All tumor cells of transplanted tumors were positive for alpha-smooth muscle actin (ASMA) but almost negative for desmin as were epithelioid cells of the original tumors, and the cell lines were positive for desmin but not for ASMA. These results suggested that mesothelioma in the F344 rat had the potential for wide spectrum differentiation under in vitro conditions. The microenvironmental factors obtained in vivo can modify their potential ability and their morphological aspects. These factors may be related to tumor cell reexpression of ASMA of tumor cells that were masked under in vitro culture conditions.

Ultrasonography of abdominal cavitary parenchymal lesions

Cavitary parenchymal lesions are composed of varying amounts of soft tissue, fluid, and/or gas. These cavitary lesions are focal or multifocal and therefore readily detected ultrasonographically. The ultrasonographic appearance of cystic and noncystic cavitary lesions are described. Differential diagnoses for these cavitary lesions in abdominal organs are listed.

Ultrasonography of the adrenal glands in the dog, cat, and ferret

Ultrasonography has become an important modality for imaging adrenal glands in small animals. Normal adrenal glands and structural abnormalities, such as changes in size, shape, and echogenicity, can be identified. In the case of adrenal tumors, ultrasonography is a valuable tool for identifying neoplastic masses with local and regional involvement, as well as potential abdominal metastases. When correlated with clinical findings and results of hematologic, serum biochemical and endocrine tests, ultrasonographic findings make a substantial contribution to the diagnosis of adrenal diseases in dogs, cats, and ferrets.

Uterine adenocarcinoma with abdominal carcinomatosis in a beluga whale

A case of uterine adenocarcinoma is reported in a 26-yr-old, free-ranging beluga whale (Delphinapterus leucas) from the St. Lawrence estuary (Quebec, Canada). This neoplasm appeared as a segmental stenotic thickening of the left uterine horn composed of well differentiated, but disorganized and infiltrative, glandular structures surrounded by an extensive scirrhous stroma. Abdominal carcinomatosis was observed on the mesosalpinx and on the serosal aspect of the gastric compartments. This is the first report of a malignancy originating in the uterus of a cetacean.

Principles of oncologic abdominal surgery

The principles of abdominal oncologic surgery parallel the general principles of all types of oncologic surgery with some variations peculiar to the abdomen. Due to the presence of multiple organ systems within the abdominal cavity, many types of cancer can develop. The surgeon must be prepared to perform several different abdominal procedures depending on the organ system involved and the extent of the cancer. The surgeon as oncologist must be aware of the tumor type, its expected behavior, and current treatment options. This article describes the principles of performing cancer surgery, including preparation for abdominal exploration, methods to facilitate tumor removal, and ways of avoiding tumor recurrence.