Epidemiological and Pathological Characterization of Feline Injection Site Sarcomas in Southern Brazil.

Feline injection site sarcoma (FISS) is a mesenchymal neoplasm with highly malignant characteristics. These tumours originate in anatomical sites where there has been previous parenteral administration of medicinal substances or implantation of medical devices. The aim of this study was to investigate the epidemiological and pathological features associated with FISS in the southern region of Brazil. The database of the Department of Veterinary Pathology of the Federal University of Rio Grande do Sul was searched for excisional and incisional biopsy samples compatible with FISS submitted between 2007 and 2017. Biopsy reports were reviewed and epidemiological information, including breed, age and sex of affected cats, as well as gross findings including anatomical location and size of the tumour and the presence of tissue invasion, were extracted. Eighty-nine samples were selected based on the established criteria. Most animals were of undefined breed and were female cats with a median age of 10 years. Grossly, 84.8% of the tumours were >2 cm in diameter. Regarding anatomical location, 34.9% of the tumours were located in the subcutaneous tissue of the thoracic wall, 29.2% in the flank, 21.3% in the interscapular region and 14.6% in the limbs. Histologically, the tumours originated in the subcutaneous tissue and were diagnosed as malignant mesenchymal neoplasms. Most were compatible with fibrosarcomas, but variants with features of pleomorphic sarcoma or chondrosarcoma were recognized. All tumours exhibited areas of necrosis and peripheral inflammatory infiltrate, composed predominantly of lymphocytes, plasma cells and macrophages. The results of this study suggest the need for dissemination of information on FISS epidemiology and guidelines for management of this tumour to veterinarians in the region.

Bilateral Anterior Uveitis in a Northern Saw-whet Owl (Aegolius acadicus) With a Metastatic Pectoral Malignant Mesenchymoma.

A captive, adult, male northern saw-whet owl (Aegolius acadicus) was examined for blepharospasm of the left eye. The owl was diagnosed with bilateral anterior uveitis and a corneal ulceration in the left eye. It was treated with oral and topical nonsteroidal anti-inflammatory medications and a topical antibiotic. Multiple recheck examinations and medication adjustments were performed over the next 4 months, at the end of which time the bilateral anterior uveitis was controlled with a topical nonsteroidal anti-inflammatory applied 3 times per week to both eyes. The owl was re-examined 2 months later after 2 suspected neurologic episodes. On physical examination, the owl was quiet and had difficulty standing and ambulating. Five firm multilobular and immobile masses were identified overlying the pectoral muscle and sternum. Fine-needle aspiration from 1 mass revealed neoplastic cells consistent with a sarcoma. The owl was euthanatized. On the basis of results of histopathologic examination, the mass was diagnosed as a pleomorphic spindle cell sarcoma with features of rhabdomyosarcoma, liposarcoma, and osteosarcoma. Numerous tumor cells were immunopositive for myoglobin and desmin, indicating striated muscle origin. Although a metastatic lesion was present in 1 adrenal gland, lesions of inflammation or neoplasia were absent in either eye on histopathologic examination. This report describes an apparent ocular manifestation of systemic disease in an avian species with clinically diagnosed recurrent anterior uveitis.

Malignant mesenchymoma with widespread metastasis including bone marrow involvement in a dog.

A male castrated Golden Retriever was presented for evaluation of a large mass over the left shoulder extending to the lower part of the neck that had been present for an extended period of time, but had a recent history of rapid growth. Previous aspirates of the mass were consistent with a lipoma. The mass was surgically excised and was diagnosed as an extraskeletal osteosarcoma based on histopathology. After surgery, the dog was initiated on a chemotherapy protocol with carboplatin and metronomic cyclophosphamide. He became neutropenic, anemic, and thrombocytopenic 14 days after the carboplatin treatment was administered. The neutropenia resolved, but the anemia and thrombocytopenia progressed. A bone marrow aspirate revealed erythroid hypoplasia, myeloid hyperplasia with a predominance of early precursors, and a subset of cells that made up 20% of the total population that were reported as bizarre and unclassifiable. These cells were discrete in nature and were thought to be hematopoietic in origin. The dog was euthanized due to deterioration of the clinical condition. On postmortem examination, widespread metastasis involving the lungs, liver, kidney, heart, and bone marrow was found. Histopathology of the tumor lesions determined 2 distinct malignant populations of liposarcoma and osteosarcoma, consistent with malignant mesenchymoma. However, the possibility of 2 separate neoplastic processes cannot be definitively excluded. This is the first report of bone marrow metastasis of a malignant mesenchymoma in a dog.

Bovine papillomavirus type 2 infection and a series of mesenchymal tumors of the urinary bladder in cattle.

This report describes the histopathology of two hundred and fifty-three mesenchymal tumors of the urinary bladder in cattle grazing on lands rich in bracken fern. Approximately 80% were hemangiomas and angiosarcomas. Hemangioma (capillary, cavernous, and large vessels) was the most frequent mesenchymal tumor and was more common than angiosarcoma. Although the appearance of endothelial cells can vary remarkably, epithelioid angiosarcomas, often containing multinucleated cells, were the most frequent malignant vascular tumors. Hemangiopericytoma and tumors of muscle and soft connective tissue origin, alone and/or in association with tumor-like lesions, were less frequently seen. Furthermore, forty-five cases of intravascular papillary endothelial hyperplasia (IPEH), a lesion not previously reported in the urinary bladder of cattle, were also described. Bovine papillomavirus type-2 DNA was amplified in tumor samples. Forty vascular tumors were investigated by dual-labeling immunofluorescence, and, for the first time, a coexpression of E5 and platelet-derived growth factor ß receptor (PDGF ß R) was shown to occur. The results show that the BPV-2 E5 oncoprotein binds to the activated form of the PDGF ß receptor thus playing an important role in mesenchymal as well as epithelial carcinogenesis of the urinary bladder. Furthermore, these findings demonstrate that BPV-2 infects both epithelial and mesenchymal cells.

Diagnosis and treatment considerations in a case of malignant mesenchymoma in an African fur seal (Arctocephalus pusillus).

A 20-yr-old African fur seal (Arctocephalus pusillus) presented with a slowly growing mass located on the dorsum at the level of the last thoracic vertebrae. The mass was hard, 10 cm in diameter, and not adherent to the underlying tissues. Multiple biopsies were collected for histopathology and revealed extensive areas of necrosis, small nodules of malignant mesenchymal proliferation with areas of chondroid metaplasia, and atypical cells in vessel walls. The morphologic diagnosis was suggestive of malignant mesenchymal neoplasia originating from the vascular wall. The mass was removed 1 mo later due to ulceration and infection. Histologically, based on the World Health Organization's classification of neoplastic processes in domestic animals, the tumor was consistent with malignant mesenchymoma. The margins of resection revealed the presence of neoplastic cells. Based on these results, the particular species involved, the high local invasiveness, and the high metastatic index of this malignant tumor in domestic mammals and humans, the prognosis was poor. The animal died 6 mo later with metatastic disease.

Malignant mesenchymoma of the heart base in a dog with infiltration of the pericardium and metastasis to the lung.

A 9-year-old male rottweiler was presented with abdominal distension, ascites and respiratory distress and marked bulging in the perineal region. At necropsy examination the animal had profuse ascites and hydropericardium and a multinodular mass in the right auricle of the heart infiltrating the epicardium and pericardium and metastasizing to the caudal lobe of the left lung. Microscopically and immunohistochemically the tumour was composed of neoplastic cells with muscular, cartilaginous and adipose differentiation. A diagnosis of malignant mesenchymoma with leiomyosarcomatous (≈ 50%), rhabdomyosarcomatous (≈ 30%), chondrosarcomatous (25%) and liposarcomatous (5%) components was made. Metastatic malignant mesenchymoma has not been reported previously at this site in the dog.

Malignant mesenchymoma in the nasal cavity of a bull.

A 4-year-old bull was presented with facial distortion and abnormal respiratory noise. Endoscopically, a proliferative mass was found obliterating the left nasal cavity and a tumour was suspected. The head was examined after slaughter and there was a well-circumscribed solid structure (15×12×6 cm) extending into the paranasal sinus, the choanal region and the bones of the orbit, with focal penetration of the nasal septum. Microscopically, the mass consisted of well-differentiated trabeculae of woven and lamellar bone, areas of chondromyxomatous, immature and mature cartilaginous tissue, and regions with irregular whorled spindle cells. Tissue differentiation of the mass was variable. Centrally, there was osseous differentiation with an outermost fibromatous area resembling a zone of endochondral ossification. There was suppurative and ulcerative inflammation where the tumour extended through the hard palate and into the pharynx. A nasal malignant mesenchymoma was diagnosed on the basis of these features.

An intra-abdominal malignant mesenchymoma associated with nonabsorbable sutures in a ferret (Mustela putorius furo).

A 6-year-old ferret (Mustela putorius furo) was presented with abdominal enlargement. Clinical examination revealed an intra-abdominal mass measuring approximately 5 cm in diameter. Abdominal survey radiographs revealed a sharply marginated mass with multifocal radiodense foci, suggestive of pathologic calcification. A complete blood cell count revealed a moderate, normocytic, normochromic, nonregenerative anemia. The mass was surgically removed en bloc, fixed in 10% neutral buffered formalin solution, and routinely processed for histologic and immunohistochemical investigation. The neoplastic tissue consisted of a mixed neoplastic cell population, including osteosarcoma and fibrosarcoma components. Immunohistochemistry revealed that both neoplastic cell populations were positive for vimentin and negative for actin (smooth and striated), desmin, and myoglobin. Nonabsorbable suture material was admixed with the neoplastic tissue in the histologic section. This material was birefringent when viewed microscopically under polarized light.

Intermandibular malignant mesenchymoma in a crossbreed dog.

A 12-year-old German shepherd crossbreed dog was presented with a submandibular mass that was initially diagnosed as myxosarcoma on incisional biopsy. Chest radiographs were taken for staging, and magnetic resonance imaging was performed to assess the feasibility of cytoreductive surgery before adjuvant radiotherapy. The dog underwent debulking surgery, and histology permitted reclassification of the tumour as a malignant mesenchymoma (with myxosarcomatous and osteosarcomatous differentiation). The dog was subsequently treated with four fractions of radiotherapy given at seven-day intervals and three doses of carboplatin. The dog remained stable following therapy until its condition acutely deteriorated, and it was euthanased 153 days after surgery. On postmortem examination, there were no signs of local tumour recurrence, but metastases were observed both in the thorax and in the abdomen.

Primary malignant mixed mesenchymal tumour of the heart in a dog.

A case of primary malignant mixed mesenchymal tumour of the heart in an 8-year-old golden retriever is described. The cardiac tumour, measuring 2.5 x 3 x 5 cm, was located in the posterior part of the atrial septum, extending into the surrounding region. Histologically, the tumour was composed of multiple mesenchymal elements of fibrosarcoma, rhabdomyosarcoma, liposarcoma and chondrosarcoma. No previous reports of such a tumour occurring in the heart of the dog were found in the literature.

Malignant mesenchymoma associated with an unusual vasoinvasive metastasis in a dog.

A case of a malignant mesenchymoma with an unusual, vasoinvasive, metastatic behavior in a three-year-old, intact female basset hound is presented. Malignant mesenchymomas are rare neoplasms in humans and in dogs. No previous reports of a malignant mesenchymoma with vasoinvasive metastasis in the dog were found in the literature. The constituent neoplasms are discussed in relation to reports in the human and veterinary literature, and a potential etiology for this unique presentation is hypothesized.

Mixed mesenchymal tumor in the kidney of a young beagle dog.

A rare spontaneous tumor was detected in the kidney of an 11-mo-old beagle dog. The tumor was a well-circumscribed cortical mass and was composed of a heterogeneous population of connective tissue cell types. While the primary cell type was a spindle cell associated with prominent collagen deposition, other areas contained bands of smooth muscle cells and poorly cellular myxomatous tissue. The presence of smooth muscle cells was confirmed by transmission electron microscopy and immunoperoxidase techniques. Based on the results, the tumor was diagnosed as a benign mixed mesenchymal tumor.

Ectomesenchymoma of the medulla oblongata in a calf.

An ectomesenchymoma was found in a 62-day-old female calf, and examined immunohistochemically. The neoplastic cells were characterized by positive immunostaining for neurofilaments, glial fibrillary acidic protein, alpha smooth muscle actin, myoglobin, and keratin. This tumour, which displayed neurocytic, astrocytic, and myoblastic differentiation, may have arisen from pluripotential ectomesenchyme. Brain tumours showing multidirectional phenotypic expression presumably occur mainly in fetuses or calves.

[Two mesenchymal tumor cell lines for the determination of natural killer (NK) cell activity in the peripheral blood of dogs]. / Zwei mesenchymale Tumorzellinien zur Bestimmung der Natürlichen Killer (NK)-Zell-Aktivität im peripheren Blut des Hundes.

The two mesenchymal cell lines K1 and K6 were established from round cell tumours located at the lips of two dogs. Both cell lines were characterized as being of myelomonocytic origin by morphological, cytochemical, immunocytochemical and functional criteria. In the 51chromium release assay (effector/target cell ratio 100/1) the K6-cell line revealed a mean cytotoxic sensitivity of 53.6% and thus showed a susceptibility similar to that of the epithelial CTAC line (57.8%). The K1-cell line exhibited less cytotoxic activity (41%) when incubated for 14 h, but showed results comparable to the K6-cell line, when the incubation time was reduced to 8 h.

Primary mesenchymal or mixed-cell-origin lung tumors in four dogs.

Primary lung tumors of mesenchymal or mixed cell origin were diagnosed in 4 dogs with clinical and radiographic abnormalities indicating an intrathoracic mass. Each dog had 1 large intrapulmonary lesion, and 1 dog also had nodules scattered throughout all lung lobes. Two dogs were euthanatized; 1 had a biphasic pulmonary blastoma; and the other had a pulmonary chondroblastic osteosarcoma with intrapulmonary metastases. The masses in the other 2 dogs were hamartomas (lipomatous in 1, microcystic in the other), which were resected. Both dogs survived more than 1 year after surgery. Primary lung tumors are uncommon in dogs and are generally malignant (adenocarcinomas or carcinomas). Tumors of connective tissue or mixed cell origin are rare, but the outcome is potentially good after surgical removal.

Spontaneous renal neoplasms in rats.

Spontaneous renal neoplasms in the rat are uncommon. This paper presents the incidence and histopathological features of various long-term developing renal tumors observed in control rats from 17 carcinogenicity studies (1340 males and 1329 females) in Sprague-Dawley rats and 10 carcinogenicity studies (530 males and 530 females) in Fischer-344 (F-344) rats. Renal cell adenoma (0.08% in Sprague-Dawley and 0.28% in F-344), lipoma/liposarcoma (0.37% in Sprague-Dawley and 0.75% in F-344) and transitional cell carcinoma (0.07% in Sprague-Dawley and 0.09% in F-344) were observed in both Sprague-Dawley (0.49%) and F-344 (1.13%) rats. Pulmonary metastasis was observed from one case of transitional cell carcinoma. Renal cell carcinoma with metastasis to the lung and liver was seen in one F-344 rat. In addition, transitional cell papilloma and nephroblastomas were also observed in Sprague-Dawley rats. Metastases from nephroblastoma were seen in the lungs and renal lymph node in two cases. In both rat strains, the tumor incidence was higher in males than in females.

Distinctive unclassified mesenchymal tumor of the digit of dogs.

Four examples of a mesenchymal tumor of undetermined histogenesis occurred in three mixed-breed dogs and one Yorkshire terrier. All tumors occurred as solitary, soft to firm, solid, tan, and ulcerated masses in the digits of dogs aged 11 to 15 years. The compact cellular tumor had cells with anisokaryotic round, oval, or irregular nuclei, some of which were multinucleated. The neoplastic cells appeared to arise in the tissue near the third phalanx in the area of dense collagenous trabeculae located proximal to the fat pad and sweat glands. The unclassifiable cells had some features of histiocytes by transmission electron microscopy, but failed to stain for lysozyme and alpha-1-antichymotrypsin, markers for monocyte-macrophage derived cells. Immunohistochemically, the cells stained for vimentin but not for cytokeratins, desmin, S-100 protein, epithelial membrane antigen, alpha-lactalbumin, lysozyme, alpha-1-antichymotrypsin, alpha-lactalbumin, casein, and heavy and light chain immunoglobulins. The combined findings of light and transmission electron microscopy and immunohistochemistry exclude tumor histogenesis from an epithelial cell, melanocyte, mast cell, plasma cell, Schwann cells, and Merkel cell.

The expression of intermediate filaments in canine mammary glands and their tumors.

Monoclonal antibodies specific for different types of intermediate filaments (cytokeratin, vimentin, desmin and neurofilaments) were used to study the histogenesis of canine mammary glands and 57 canine mammary tumors by immunocytochemistry. The intra- and interlobular duct epithelium, acinar, and intralobular myoepithelial cells stained positively for cytokeratin. Peripheral ductal and acinar cells, as well as interstitial cells, stained positively for vimentin. A similar staining pattern was seen in adenomas, complex adenomas, benign mixed tumors, ductular carcinomas, and one myoepithelioma-like tumor. Additionally, cytokeratin positive cells were scattered interstitially in one single adenoma, most complex adenomas, some benign mixed tumors, complex carcinomas, and in the malignant mixed tumors. All stromal cells stained positively for vimentin. The fibrosarcomas were positive only for vimentin, while the following expressed both desmin and cytokeratin: epithelial-like cells in one adenoma, three complex adenomas, the myoepithelioma-like tumor, the single comedo carcinoma, two complex carcinomas, the single lobular carcinoma, one malignant mixed tumor, and three osteosarcomas. Epithelial-like cells in one adenoma, six complex adenomas, two benign mixed tumors, two complex carcinomas, the lobular carcinoma, and the malignant schwannoma stained for neurofilaments. Three tumors, one adenoma, one complex adenoma, and the lobular carcinoma expressed both desmin and neurofilaments in addition to cytokeratin and vimentin. The results show the expression of different types of intermediate filaments and indicate that there might be a stem cell origin in most of the canine mammary tumors.

Use of cisplatin for control of metastatic malignant mesenchymoma and hypertrophic osteopathy in a dog.

Cisplatin (cis-diammine-dichloroplatinum) treatment induced partial remission of pulmonary metastatic malignant mesenchymoma and nearly complete radiographic remission of hypertrophic osteopathy in a 14-year-old Beagle. Cisplatin was given once every 3 weeks. Clinical signs of hypertrophic osteopathy resolved one week after initiation of treatment. Partial remission of pulmonary metastases and partial radiographic remission of hypertrophic osteopathy was seen 6 weeks after initiation of treatment. Previous treatment of neoplasia-related hypertrophic osteopathy has consisted of removal of the initiating mass or vagotomy. In this case, appropriate chemotherapy was used to control clinical signs and progression of hypertrophic osteopathy.