Immunohistochemical evaluation of canine peripheral nerve sheath tumors and other soft tissue sarcomas

Localized, plexiform, diffuse, and other variants of neurofibroma in 12 dogs, 2 horses, and a chicken

In humans, neurofibroma and schwannoma are distinct entities within the group of benign peripheral nerve sheath tumors. In the veterinary literature, these tumors are often classified together simply as benign peripheral nerve sheath tumors, and diagnostic criteria for their subclassification are not well established. We describe peripheral nerve sheath tumors with microscopic, immunohistologic, and ultrastructural features similar to those in subtypes of human neurofibroma in 12 dogs, 2 horses, and 1 chicken. Dogs were of different breeds and were aged 2 months to 15 years. The canine tumors were located in the skin, peripheral nerve, tongue, and large intestine. The 2 horses were 11 and 12 years old. The equine tumors were located in the subcutis of the neck and axilla. The chicken was a mature white Leghorn chicken with an ocular neoplasm. Neurofibromas of this study had localized, plexiform, diffuse and combined plexiform and diffuse growth patterns, and microscopic features similar to those in classic, collagenous, cellular, myxoid, and pigmented neurofibromas of humans. One diffuse neurofibroma contained areas of schwannian differentiation (hybrid neurofibroma-schwannoma). Two plexiform neurofibromas occurred together with diffuse ganglioneuromatosis in the large intestine of young dogs, as has also been reported in humans. This investigation shows the existence of identical subtypes of neurofibroma in animals and humans and identifies similarities in tumor location and patient age between animals and humans. This report will allow a more discriminating classification of benign peripheral nerve sheath tumors and probably has a bearing on epidemiology, pathogenesis and prognosis.

Histologic Grade Predicts Recurrence for Marginally Excised Canine Subcutaneous Soft Tissue Sarcomas

Local recurrence of marginally excised subcutaneous soft tissue sarcomas is variable and difficult to predict. This study aimed to identify predictors of local recurrence after excisional biopsy. Medical records of 236 dogs from which tumors had been received between 2004 and 2007 were analyzed. Medium- to large-breed dogs, median age 10 years, were most commonly affected. A total of 139 tumors were graded histologically: 71 were grade 1 (51%); 59, grade 2 (42%); and 9, grade 3 (7%). Of these, 34 tumors (25%) were completely excised, and 104 (75%) were marginally excised. None of 30 completely excised tumors with follow-up information recurred. Three of 41 grade 1 tumors (7%), 14 of 41 grade 2 tumors (34%), and 3 out of 4 grade 3 tumors recurred after marginal excision. Kaplan-Meier survival curves were generated to evaluate survival and the tumor-free interval. The log-rank test and log-rank test for trend were used for comparisons. Tumor recurrence-free intervals for dogs with grade 1 and 2 tumors and for those with grade 1 and 3 tumors differed significantly ( P = .0027 and .0001, respectively) and overall were inversely related to tumor grade ( P = .0007). Kaplan-Meier survival curves, regardless of recurrence, for patients with grade 1, 2, or 3 tumors treated by marginal excision did not differ significantly, and none differed from the survival curves of patients treated by complete excision. In conclusion, histologic grade is a strong predictor for recurrence of marginally excised subcutaneous soft tissue sarcomas. Clean margins predict nonrecurrence. Tumor recurrence did not significantly reduce survival time.

Malignant acoustic schwannoma in a dog

A malignant schwannoma of the right acoustic nerve of a dog is described. The neoplasm was found during necropsy of a 12-year-old, spayed, female Labrador Retriever that experienced a sudden onset of severe pain in the neck and upon opening the mouth. Concurrent mild hind limb ataxia also was present. The tumor had infiltrative growth, and the spindle-shaped neoplastic cells were arranged in sheets and concentric whorls. Immunohistochemical staining of the neoplastic spindle cells was positive for S-100 antigen, neuron-specific enolase, and glial fibrillary acidic protein.

Ultrasound-guided fine needle aspiration in the diagnosis of peripheral nerve sheath tumors in 4 dogs

Ultrasound-guided fine needle aspiration was used in establishing the diagnosis in 4 cases of malignant peripheral nerve sheath tumor. Sonographic and cytologic characteristics are discussed. Because of its availability and ease of use, axillary ultrasonography with fine needle aspiration can be an initial diagnostic step for suspected brachial plexus tumors.

Malignant peripheral nerve sheath tumor of the diaphragm in a dog

An 11-year-old, castrated male greyhound was referred to the Michigan State University Veterinary Teaching Hospital for surgical removal of a thoracic mass. Thoracic radiographs revealed a smoothly marginated mass obscuring the diaphragm in the left caudal thorax. Ultrasonographic and computed tomographic imaging modalities demonstrated a mass originating from the left hemidiaphragm. The mass was surgically removed and submitted for histopathological evaluation. Histopathology and immunohistochemical staining confirmed a malignant peripheral nerve sheath tumor.

Benign Peripheral Nerve Sheath Tumor of the Perianal Region in a Young Pony

A 20 × 10 cm, lobulated mass was present in the perianal region of a 4-year-old Dales pony. Histopathology revealed an unencapsulated, loose arrangement of sheets and whorls of narrow mesenchymal cells, situated in the deep dermis. Intervening areas had a myxomatous appearance. The whorls were often arranged around a central structure resembling an axon or a vascular structure. Immunohistochemistry revealed that the elongated mesenchymal cells and central axon-like structures expressed vimentin, S-100, and neuron-specific enolase, but not pancytokeratin, glial fibrillary acid protein, and the neurofilament markers. NR4 and 2F11. On the basis of the histopathology and immunohistochemistry, a diagnosis of benign peripheral nerve sheath tumor (schwannoma type) was made. This case was unusual in that the concentric laminations of Schwann cells were very loosely arranged, with an intervening myxomatous stroma (Antoni type B appearance) and despite its benign histological appearance, the mass extended deeply to the proximal sacral vertebrae. Its exact origin was unclear; it may have arisen from cutaneous nerves with deep extension or from neural structures in the sacral region. Due to the incomplete surgical removal, regrowth of the mass occurred.

Immunoreactivity of Bovine Schwannomas

Thirty schwannomas from 22 cows were examined immunohistochemically. All were positive for vimentin and Ki-67 but negative for pancytokeratin, neurofilament, and desmin. S-100 immunolabelling varied between and within lesions. The numbers of tumours giving positive results for S-100, neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) were 16, 30 and 25, respectively. It was concluded that vimentin-positive tumours suspected to be schwannomas should also be immunolabelled for NSE and GFAP to confirm the diagnosis.

Aspectos histoquímicos e imunoistoquímicos nos neoplasmas do sistema nervoso periférico

Doze casos de tumores do sistema nervoso periférico, sete schwannomas e cinco neurofibromas foram diagnosticados entre 1964 e 2004, em caninos e bovinos. Histologicamente, as células predominantes nos schwannomas eram fusiformes organizavam-se em paliçada ou em feixes aleatórios. Nos neurofibromas as células neoplásicas eram fusiformes e se originavam da periferia dos nervos formando ninhos e feixes. O tecido conjuntivo era mais abundante nos neurofibromas e os colágenos dos tipos I e III eram os principais constituintes desses neoplasmas. Os neurofibromas foram caracterizados por uma concentração alta e difusa de mastócitos, provavelmente devido à origem das células neoplásicas do perineuro e epineuro. A coloração de AgNOR não se mostrou eficiente como indicador de prognóstico nos neoplasmas analisados. Imunoistoquímicamente houve forte marcação para vimentina (100%) e S100 (100%) em ambos os tipos de tumor. A maioria dos schwannomas (75%) foi positiva para a proteína ácida fibrilar glial; os neurofibromas só apresentaram marcação nas células de Schwann dos fascículos nervosos.

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.

Tumor maligno da bainha de nervo periférico em cães: relato de três casos

Descrevem-se os achados anatomoclínicos e imunoistoquímicos dos tumores da bainha de nervos periféricos em três cães atendidos em hospital. Os animais apresentavam sintomatologia variável de acordo com a localização do tumor. À microscopia, as neoplasias eram invasivas e constituídas por células pleomórficas e anaplásicas que variavam de poligonais a fusiformes, arranjadas em padrão sólido difuso, por vezes em paliçada. Foi firmado o diagnóstico de tumor da bainha de nervos periféricos nos três casos.

The immunohistochemical characterization of devil facial tumor disease (DFTD) in the Tasmanian Devil (Sarcophilus harrisii)

Immunohistochemical techniques were used to characterize the disfiguring and debilitating fatal neoplastic disease, devil facial tumor disease (DFTD), which has recently affected a significant proportion of the wild population of Tasmanian Devils (Sarcophilus harrisii). The diagnostic values of a number of immunohistochemical stains were employed to further characterize 50 representative cases. The neoplasms were negative for cytokeratin (0/48), epithelial membrane antigen (0/42), von Willebrand factor (vWF) (0/11), smooth muscle actin (SMA) (0/26), desmin (0/47), glial fibrillary acid protein (0/13), CD16 (0/13), CD57 (0/43), CD3 (0/18), and LSP1 (0/16). DFTD cells were positive for vimentin (50/50), S-100 (41/48), melan A (11/39), neuron specific enolase (35/35), chromogranin A (12/12) and synaptophysin (29/30). The cells were negative for amyloid (0/30) and stained negatively with Singh's silver (0/34) but were weakly argyrophilic (3/40) using Grimelius histochemical stain. These staining characteristics are consistent with cells of neuroectodermal origin.

Cellular Neurofibroma with Atypia Mimics Sarcoma: Report of a Case with Immunohistochemical Staining Pattern Analysis and Literature Review

A case of two sporadic cellular neurofibromas with atypia and one widespread hyalinization neurofibroma of the lumbar spine in a 51-year-old man without evidence of neurofibromatosis-1 is reported. Cellular neurofibroma with atypia is an unusual variant. The definite criteria for low-grade and high-grade malignant peripheral nerve sheath tumors as well as cellular neurofibroma are not well defined in the literature. The clinical significance of atypical cellular neurofibroma has rarely been systematically studied. To our knowledge, the concomitance of cellular architecture and cytologic atypia is rarely documented, and this is a rare report of atypical cellular neurofibroma. The recognition of this entity is of great importance to both pathologists and clinicians because atypical cellular neurofibroma is clever at masquerading both histologically and cytologically as a sarcoma; therefore, a precise diagnosis of this variant is essential because of the differences in treatment and clinical behavior between benignancy and malignancy. We also examined the immunohistochemical characteristics of CD34 positive cells and focal high expression of p53 up to 73% encountered in our case. To our knowledge, seldom have series or case reports elucidated this phenomenon.

Multicentric malignant Schwannoma in a crossbred cow

Multicentric malignant Schwannoma in a crossbred cow is described. Multiple and solitary nodules of varying sizes were seen to be distributed throughout the body of the animal, mainly along the peripheral nerves supplying the muscles of the thoracic and abdominal regions and the skin. Multiple nodules were also observed in the hilus of the liver. The mediastinal lymph nodes were replaced by a large solitary tumorous mass. Multiple neoplastic linear cords with small nodules were observed on the pericardium. Histologically, the nodules showed mainly densely packed, spindle-shaped cells arranged in short interwoven bundles and whorls (Antoni type A pattern). Stellate, spindle-shaped and round or oval tumour cells proliferated haphazardly within the loose texture of a collagenous matrix (Antoni type B pattern). Immunohistochemically, in both Antoni type A and type B areas, neoplastic cells reacted with antibodies against S-100 protein. Based on the metastasis of the tumour to the lymph nodes and on histology, the neoplasm was diagnosed as a multicentric malignant Schwannoma.

Immunoprofiles in malignant peripheral nerve sheath tumor: three case reports and literature review

Because there are no standardized radiologic and histologic criteria, the differential diagnosis of malignant peripheral nerve sheath tumors (MPNSTs) from other spindle cell neoplasms poses great challenges for pathologists. Because early diagnosis of MPNSTs arising from benign peripheral nerve sheath tumors (BPNSTs) means a better prognosis, many immunohistochemical and molecular studies have recently emerged. Nevertheless, no gold standard diagnostic criterion is to be found in the literature. For example, S-100 protein is widely used in the diagnosis of MPNST. Other promising ancillary markers are p53 and Ki-67; however, the staining patterns and possible mechanisms of these markers are seldom mentioned in the literature. These evoke our interest. Only six cases diagnosed as MPNST were retrieved from the archives of the Department of Pathology, Kaohsiung Medical University Chung-Ho Memorial Hospital between 1988 and September 2005. Clinical files were available for three of them, and we found nuances in the immunohistochemistry from these previous reports. Here, we present these rare sarcomas and review the literature.

Primary haemangiopericytoma in the pelvic cavity of a dog

A 9-year-old female Yorkshire terrier with lameness of the hind leg was examined at the local animal hospital in Gwangju, Republic of Korea on March, 2004. The radiological findings revealed a mass between the urinary bladder and cervix of the uterus. The encapsulated pelvic mass, measuring 4.0 x 3.0 x 2.5 cm was surgically removed. Grossly, the mass was white and firm and microscopically showed a perivascular whorled pattern of spindle cells. By immunohistochemistry, tumour cells tested positive for vimentin and alpha-smooth muscle actin, and negative for desmin, S-100, lysozyme and cytokeratin. The tumour was diagnosed both histologically and immunohistochemically as a haemangiopericytoma. There were no signs of recurrence within 12 months after surgery. This is the first case report of a haemangiopericytoma in the pelvic cavity of a dog.