Spinal oligodendroglioma with diffuse arachnoidal dissemination in a Japanese Black heifer

A gelatinous focus with cystic spaces, was found in the posterior funiculus of the 2nd to 3rd lumbar levels of the spinal cord of a Japanese Black heifer, 2 years old, with clinical signs of severe dysstasia. Histopathological examination revealed that the spinal lesion consisted of multifocal and diffuse proliferation of round cells with abundant vacuolar cytoplasm and hyperchromatic nuclei. In the lesions there was a number of cystic spaces containing aggregates of small round cells. The neoplastic foci showed a honeycomb structure divided by thin blood vessels, representing typical lesions of oligodendroglioma. Diffuse and multifocal proliferation of these round cells were also recognized in the subarachnoidal space in the sacral spinal cord. Immunohistochemically, the proliferating round cells were negative for glial fibrillary acidic protein. Based on these morphological features, the case was diagnosed as lumbar spinal oligodendroglioma with diffuse arachnoidal dissemination.     

Spontaneous Malignant T-cell Lymphoma in a Young Adult Crl:CD (SD) Rat

We investigated a case of spontaneous malignant T-cell lymphoma observed in a 19-week-old male Crl:CD (SD) rat. The rat showed paralysis beginning 1 week before euthanasia. Hematological examination revealed marked lymphocytosis without distinct atypia. Macroscopically, hepatosplenomegaly and partial atrophy of the thoracic spinal cord were observed. Microscopically, neoplastic cells infiltrated into the liver, splenic red pulp, bone marrow and epidural space of the thoracic spinal cord, while no neoplastic cells were observed in the thymus and lymph nodes. Moreover, the spinal cord showed focal degeneration due to compression by marked infiltration of neoplastic cells in the subdural space. The neoplastic cells were generally small-sized round cells that had a round nucleus with/without a single nucleolus and scanty cytoplasm. Immunohistochemically, the neoplastic cells were positive for CD3 and CD8 and negative for CD79α. Judging from these results, the present tumor in this young adult rat was diagnosed as malignant T-cell lymphoma.     

Possible intraspinal metastasis of a canine spinal cord nephroblastoma

A 2-year-old Basset Hound was admitted to the University of Florida Veterinary Medical Teaching Hospital with progressive spastic paraparesis. At necropsy, intradural extramedullary tumors produced areas of spinal cord swelling and softening in spinal cord segments T11-T12 and L4-L6. Histologic examination of the masses revealed sheets of polygonal blastemal cells, epithelial cells forming tubules and rosettes, and embryonal glomeruloid-like structures in the thoracic mass. Cells in the lumbar mass were less differentiated, forming rare tubules and no glomeruloid-like structures. The occurrence of two tumors in the spinal cord along with the less differentiated appearance of the lumbar tumor raises the possibility that the lumbar mass arose as a result of intraspinal metastasis. To our knowledge, this is the first report of multifocal or metastatic canine spinal nephroblastoma. In addition, the vimentin and cytokeratin immunohistochemical staining characteristics of these spinal cord nephroblastomas are described.     

Spontaneous hemangiosarcoma in the spleen and liver of a young rat

Spontaneous hemangiosarcoma in young rats is rare. In this report, we describe a case of a spontaneous hemangiosarcoma in the spleen and liver of young rats. At necropsy, multiple pale red masses were observed in the spleen. Histopathologically, solid growth and haphazardly arranged neoplastic cells were observed, although no characteristic growth pattern was observed. In contrast, irregularly sized small slit-shaped spaces containing erythrocytes were found among the neoplastic cells. Reticular fibers incompletely surrounding the neoplastic cells were observed by silver staining. Immunohistochemistry revealed that the neoplastic cells were positive for vWF and CD34. Electron microscopic examination revealed that the neoplastic cells had erythrocytes in the lumen and Weibel-Palade bodies in the cytoplasm and were arranged along a discontinuous basal lamina. These features indicate that the tumor originated from vascular endothelial cells. Based on these results, the tumor was diagnosed as a hemangiosarcoma in the spleen and liver.     

Spinal cord glioma in a ridge-nosed rattlesnake (Crotalus willardi).

An 11-yr-old, female Arizona ridge-nosed rattlesnake (Crotalus willardi) had a 1-yr history of retained egg masses and decreased mobility in the caudal two-thirds of the body. The snake was euthanized when it became unable to right itself. At necropsy, the caudal portion of the spinal cord was found to be enlarged, soft, and translucent pale gray. Microscopically, the caudal portion of the spinal cord was segmentally replaced by a neoplastic mass composed of cells resembling glia (oligodendrocytes and astrocytes). Immunohistochemistry for glial fibrillary acidic protein was positive in the astrocytelike neoplastic cells. The gross, microscopic, and immunohistochemical findings were consistent with a diagnosis of spinal cord glioma. This is the first report of a central nervous system tumor in a reptile.     

Extensive cutaneous metastases in a dog with duodenal adenocarcinoma

Abstract: A 6-year-old Rottweiler was presented to the North Carolina State University College of Veterinary Medicine for evaluation of multiple cutaneous nodules. The dog had a history of anorexia, vomiting, and hind-limb paraplegia. Results of cytologic examination of the cutaneous nodules were consistent with a round cell tumor. At necropsy, primary tumors were found coalescing in the duodenum and the pancreas and extending into the associated mesentery. Numerous masses also were found throughout the skin, abdominal and thoracic viscera, and lumbar spinal cord. Histologically, the duodenal tumor had variable morphology, with some areas resembling adenocarcinoma and others resembling anaplastic round cell neoplasia; the skin and other metastatic lesions resembled round cell neoplasia. Immunohistochemistry of the cutaneous, duodenal, and pancreatic masses showed the neoplastic cells were positive for pancytokeratin, supporting an epithelial origin. In addition, low numbers of neoplastic cells were positive for periodic acid-Schiff and Alcian blue, consistent with acid mucin production by duodenal epithelium. These findings confirmed that the cutaneous nodules were metastatic lesions originating from the duodenal adenocarcinoma. Cutaneous metastasis of intestinal carcinoma is rare in domestic animals. This case demonstrates the potential difficulty in diagnosing metastatic lesions based on cytologic and histologic morphology alone, because the cutaneous metastases may not resemble the primary neoplasm morphologically.     

Spinal cord astrocytoma in a cat

A nine-year-old neutered male domestic shorthaired cat with a history of spinal pain and progressive hindlimb dysfunction was presented to the Norwegian School of Veterinary Science. Following neurological and myelographic examination, an intramedullary mass affecting several lumbar spinal cord segments was diagnosed. A neoplastic lesion was suspected and a poor prognosis was given. On postmortem examination, the spinal cord was found to be dorsally flattened from the 12th thoracic vertebra to the fifth lumbar vertebra and severely thickened with a dorsal cleft from the fifth to the seventh lumbar vertebra. Histologically, the tumour was diagnosed as an anaplastic astrocytoma.     

Paresis in an Asian small clawed otter (Aonyx cinereus) associated with vertebral and ischial osteolysis caused by a malignant lymphangiosarcoma

A 10-yr-old male intact Asian small clawed otter (Aonyx cinerus) was presumptively diagnosed by histopathology and immunohistochemistry with lymphangiosarcoma after bony destruction of the ischium and spinal column from local tumor invasion had caused progressive signs of hind limb lameness and paresis/paralysis, which led to humane euthanasia. At necropsy, the primary tumor was identified as a flocculent mass present under the caudal lumbar vertebrae. Multiple nerves were seen to run from the spinal cord into the wall of the mass. This mass had locally invaded the surrounding muscle, vertebral column, and spinal cord, which led to the clinical signs noted at presentation. Bony destruction was severe with almost complete obliteration of the right ischium and osteolysis of L6, exposing the spinal cord beneath. The tumor had metastasized to at least two different sites within the spleen. The abdominal tumor was confirmed to be of endothelial origin by the use of immunohistochemical staining for factor VIII-related antigen and was confirmed as lymphatic origin versus vascular origin because of the lack of red blood cells within the vessels. The length of time from initial presentation with hind limb lameness to euthanasia because of hind limb paralysis was 4 mo. This is the first report of lymphangiosarcoma, an uncommon malignant neoplasm of lymphatic origin, in a mustelid and the first report of neoplastic disease in an Asian small clawed otter. In addition, the presentation of hind limb paresis associated with bony lysis because of local tumor invasion has not been previously reported with lymphangiosarcoma in humans, domestic animals, or nondomestic animals.     

Spinal meningiomas in dogs: Description of 8 cases including a novel radiological and histopathological presentation

Clinical, imaging, and histological features of 8 canine spinal meningiomas, including a cervical cystic meningioma with imaging and intraoperative features of an arachnoid cyst, are described. All meningiomas were histologically classified and graded following the international World Health Organization human classification for tumors. Six meningiomas were located in the cervical spinal cord. Myelography showed intradural/ extramedullary lesions in 3/4 cases. Magnetic resonance imaging revealed hyperintense intradural/extramedullary masses on pre-contrast T1-weighted and T2-weighted images with homogeneous contrast enhancement in 7/8 cases. One dog had a cerebrospinal fluid-filled subarachnoid cavity dorsal to the cervical spinal cord. A spinal arachnoid cyst was diagnosed on imaging, but the histopathological study of the resected tissue revealed a grade I meningothelial cystic meningioma. There were no differences in outcome associated with tumor grade and surgical treatment (6/8). Cystic meningioma should be considered in the differential diagnosis of intraspinal cystic lesions, and biopsy is necessary for definitive diagnosis.     

Extraventricular neurocytoma of the spinal cord in a dog

Central neurocytoma is a rare, prognostically favorable neuronal tumor of the human central nervous system, typically located intraventricularly near the foramen of Monro. Extraventricular cerebral neurocytomas and spinal tumors have also been reported. To date, however, neurocytomas have not been documented in domestic animal species. In this report, we describe a spinal cord tumor in a dog. The microscopic examination revealed tumor cells forming loosely packed clusters in some areas and palisades in other areas. In addition, they showed fine fibrillary neuropil-like areas of different sizes, sometimes resembling the "rosettes" of pineocytomas, as well as ependymoma-like perivascular pseudorosettes. The tumor cells had scant eosinophilic cytoplasm, with perinuclear halos, closely resembling the appearance of oligodendroglioma. Immunohistochemical staining showed expression of synaptophysin and neuron-specific enolase by tumor cells and pronounced in fibrillary areas. On the basis of histomorphology and immunohistochemical reactivity, the present tumor was diagnosed as extraventricular neurocytoma.     

Spontaneous histiocytic sarcoma of the popliteal lymph node in a young sprague-dawley rat

The present report describes a rare case of spontaneous primary histiocytic sarcoma of the popliteal lymph node in a 19-week-old female Sprague-Dawley (SD) rat. At necropsy, a 10 mm-diameter whitish nodule was found at the site of the femoral muscle in the right hindlimb. Histopathologically, the nodule comprised large pleomorphic histiocyte-like cells with abundant eosinophilic or foamy cytoplasm. Multinucleated giant cells, necrotic foci surrounded by palisading arrays of epithelioid histiocyte-like cells and phagocytosis of cell debris or erythrocytes by the neoplastic cells were occasionally observed. Invasion of the tumor cells into the surrounding adipose tissue was found focally, but there were no distal metastases. Immunohistochemically, the neoplastic cells were positive for vimentin, CD68 (ED1) and lysozyme. We concluded that this tumor occurred in the popliteal lymph node, considering the anatomical location of the lesion and the presence of the remnants of lymphoid tissue involved in the tumor.     

Diagnostic exercise: astrocytoma with involvement of medulla oblongata, spinal cord, and spinal nerves in a raccoon (Procyon lotor)

Neoplasms affecting the central and peripheral nervous systems of wild animals are extremely rare. Described are clinical signs and pathologic and immunohistochemical findings in an adult female raccoon (Procyon lotor) with an astrocytoma that involved medulla, cervical spinal cord, and roots of the cervical spinal nerves. Microscopically, the neoplastic cells revealed some pleomorphism but generally had fusiform morphology and showed moderate numbers of mitotic figures. Glial fibrillary acidic protein was demonstrated within the neoplastic cells by immunohistochemistry. This appears to be the only reported case of astrocytoma that involved multiple anatomic sites in the central nervous system of this raccoon.     

Diffuse leptomeningeal histiocytic sarcoma in the cerebrospinal fluid of 2 dogs

Two adult male castrated dogs were evaluated for progressive paraparesis and ataxia. Neurologic examination showed severe ataxia, delayed proprioceptive placement in the pelvic limbs, pain upon palpation of the lumbar spine as well as facial paresis in one dog, and decreased withdrawal reflex of the pelvic limbs in the other dog. Magnetic resonance imaging (MRI) in both dogs showed diffuse meningeal and intramedullary lesions. However, no evidence of a mass was found. Biopsies could not be performed safely due to the location of the lesions. Cerebrospinal fluid (CSF) examination revealed an inflammatory pleocytosis associated with increased protein concentration and numerous large atypical round cells, often multinucleated. Nuclear fragmentation, micronuclei, and rare atypical mitoses were observed. Immunocytochemistry revealed CD1⁺ and CD11c⁺ staining, which, in concert with the morphology confirmed the diagnosis of histiocytic sarcoma (HS). Euthanasia was elected due to poor prognosis. Histopathologic examination showed diffuse spinal and meningeal infiltration with CD18⁺ neoplastic cells, without any evidence of mass formation, which completed the diagnosis of diffuse leptomeningeal HS involving the brain and the spinal cord. Canine central nervous system (CNS) HS has been seldom reported in the literature, with only isolated cases identified on CSF cytology. The cases reported here are remarkable in describing a diffuse CNS leptomeningeal HS associated with neoplastic cells in the CSF of dogs without a tumor mass. These cases emphasize the potential critical importance of CSF analysis in providing an antemortem diagnosis of neoplasia in neurologic patients.     

Anaplastic astrocytoma in the spinal cord of an African pygmy hedgehog (Atelerix albiventris)

A 2-year-old, female hedgehog presented with an 8-month history of progressive, ascending paresis/paralysis and was tentatively diagnosed with wobbly hedgehog syndrome. She died awaiting further diagnostic tests, and the owners consented to postmortem examination. Grossly, the bladder was large and flaccid and the cervical and lumbar spinal cord were regionally enlarged, light grey, and friable with multifocal hemorrhages. The thoracic spinal cord was grossly normal. Microscopically all regions of the spinal cord had similar changes, although the cervical and lumbar sections were most severely affected. These regions were completely effaced by a moderately cellular infiltration of highly pleomorphic polygonal to spindle shaped cells, mineralization, and necrosis, which were most consistent with anaplastic astrocytoma. The thoracic spinal cord white matter was similarly infiltrated by the neoplastic cells, with perivascular extension into the otherwise normal grey matter. A diagnosis of anaplastic astrocytoma was confirmed using immunohistochemical stains that were positive for glial fibrillary acidic protein and S100.     

A case of spontaneous Zymbal’s gland carcinoma with lung metastasis in an aged Fischer 344 rat

Zymbal’s gland neoplasms are induced in rats through the administration of various carcinogens, but spontaneous neoplasia is rare. This report describes a spontaneous Zymbal’s gland carcinoma with lung metastasis found in an aged male Fischer 344 rat. Macroscopically, the dome-like tumor nodule, approximately 30 mm in diameter with ulceration, was located near the ear canal of the rat. No healthy tissue or structure of Zymbal’s gland was identified on the corresponding side, while the normal salivary glands and a lacrimal gland were observed. Histologically, a large part of the tumor mass was occupied by poorly differentiated neoplastic cells, the shapes of which were oval to polygonal or fusiform. Additionally, clusters of sebaceous-like foamy cells and squamous metaplasia with prominent keratinization were observed. Tumor cells were found to metastasize to the lung; these cells displayed histological similarities, including a sebaceous gland-like pattern, to those in the primary site. The tumor cells were immunohistochemically positive for cytokeratin AE1/AE3 or vimentin but negative for CD68, S100, α-smooth muscle actin, von Willebrand factor, and desmin. Our results indicate that the tumor was a poorly differentiated Zymbal’s gland carcinoma with lung metastasis.     

Vitelline cyst in the rat ileum

Congenital vitelline duct anomalies other than Meckel’s diverticulum are rare in animals. A cyst of approximately 8 mm in diameter was observed on the antimesenteric surface of the ileal serosa in a 10-week-old female Crl:CD(SD) rat. Microscopically, the cyst closely resembled the ileum, but it did not communicate with the ileal lumen. We diagnosed this case as a vitelline cyst derived from the vitelline duct based on the location where it developed and its histological behavior. In rats, only Meckel’s diverticulum has been reported with a congenital anomaly of the vitelline duct, and no other spontaneous anomalies including a vitelline cyst have been reported. This case may be the first report concerning a vitelline cyst in the rat ileum.     

Oligodendroglioma in the cervical spinal cord of a dog

A 7-year-old male castrated Yorkshire Terrier dog developed slowly progressive neurologic disturbances consisting of difficulties in moving the neck, lack of proprioception, and tetraparesis 4 months prior its death. Neurologic examination, computer tomography, and myelography resulted in the tentative diagnosis of intramedullary cervicothoracic spinal cord lesion. At necropsy, an intramedullary cervical spinal cord mass between C5 and C6 was noticed. Histologically, cells of this well-demarcated, nonencapsulated neoplasm were arranged in sheaths or cords separated by a fine fibrovascular stroma. The polygonal to round tumor cells were characterized by moderate pale, basophilic, and vacuolar cytoplasm and round to slightly oval, centrally located nuclei with fine-stippled heterochromatin, a single nucleolus, and a very low mitotic activity. Tumor cells lacked glial fibrillary acidic protein, vimentin, factor VIII-related, and cytokeratin antigen expression. Histologic and immunohistochemical findings led to the diagnosis of a cervical spinal cord oligodendroglioma.     

Comparison of localization of the neurokinin 1 receptor and nitric oxide synthase with calbindin D labelling in the rat spinal cord

A comparison of the localization of the neurokinin 1 (NK1) receptor and nitric oxide synthase with calbindin D labelling in the lumbar spinal cord was carried out in the rat using immunocytochemistry. Considerable regional variations were observed. Application of the antibody to calbindin D resulted in dense staining in laminae I and II and light staining in the other laminae. Occasional scattered cells were seen in the deep laminae and in the lamina X, the ventral horn and the lateral spinal nucleus. The results indicate that neurones expressing calbindin D, NK1 receptor and NOS are three separate populations in the dorsal horn of the lumbar spinal cord.     

Occurrence of Spontaneous Tumors in the Central Nervous System (CNS) of F344 and SD Rats

In order to accurately assess the carcinogenicity of chemicals with regard to rare tumors such as rat CNS tumors, sufficient information about spontaneous tumors are very important. This paper presents the data on the type, incidence and detected age of CNS tumors in F344/DuCrlCrlj (a total of 1363 males and 1363 females) and Crl:CD(SD) rats (a total of 1650 males and 1705 females) collected from in-house background data-collection studies and control groups of carcinogenicity studies at our laboratory, together with those previously reported in F344 and SD rats. The present data on F344/DuCrlCrlj rats (F344 rats) and Crl:CD(SD) rats (SD rats) clarified the following. (1) The incidences of all CNS tumors observed in F344 rats were less than 1%. (2) The incidences of malignant astrocytoma and granular cell tumor were higher in male SD rats than in female SD rats. (3) The incidences of astrocytoma and granular cell tumor were higher in SD rats than in F344 rats. (4) Among astrocytoma, oligodendroglioma and granular cell tumor, oligodendroglioma was detected at the youngest age, followed by astrocytoma, and ultimately, granular cell tumor developed in both strains. The incidences observed in our study were almost consistent with those previously reported in F344 and SD rats.