Nerve sheath tumor in the forearm of a common marmoset (Callithrix jacchus).

Tumors of the skin and subcutaneous tissues are uncommon in marmosets. In this report, we describe the gross, histopathology, and immunohistochemical findings of a nerve sheath tumor that arose in the left forearm of an adult female marmoset (Callthrix jacchus).

Malignant Nerve Sheath Tumor of the Hypoglossal Nerve in a Maltese Dog.

A 4 yr old male Maltese dog presented with a 1 wk history of intermittent neck pain and progressive difficulty walking. Neurologic evaluation was consistent with a left-sided brainstem lesion. On oral examination, left lingual hemiatrophy was evident suggesting hypoglossal nerve involvement. A dumbbell-shaped extra-axial mass in the left side of the caudal fossa extending extracranially through the hypoglossal canal was detected by MRI. At postmortem histologic examination, the hypoglossal nerve was diffusely infiltrated by fusiform neoplastic cells arranged in Antoni A and Antoni B patterns. This is the first description of a malignant nerve sheath tumor selectively involving the hypoglossal nerve in a dog.

Curse of the devil: molecular insights into the emergence of transmissible cancers in the Tasmanian devil (Sarcophilus harrisii).

The Tasmanian devil (Sarcophilus harrisii) is the only mammalian species known to be affected by multiple transmissible cancers. Devil facial tumours 1 and 2 (DFT1 and DFT2) are independent neoplastic cell lineages that produce large, disfiguring cancers known as devil facial tumour disease (DFTD). The long-term persistence of wild Tasmanian devils is threatened due to the ability of DFTD cells to propagate as contagious allografts and the high mortality rate of DFTD. Recent studies have demonstrated that both DFT1 and DFT2 cancers originated from founder cells of the Schwann cell lineage, an uncommon origin of malignant cancer in humans. This unprecedented finding has revealed a potential predisposition of Tasmanian devils to transmissible cancers of the Schwann cell lineage. In this review, we compare the molecular nature of human Schwann cells and nerve sheath tumours with DFT1 and DFT2 to gain insights into the emergence of transmissible cancers in the Tasmanian devil. We discuss a potential mechanism, whereby Schwann cell plasticity and frequent wounding in Tasmanian devils combine with an inherent cancer predisposition and low genetic diversity to give rise to transmissible Schwann cell cancers in devils on rare occasions.

Total laryngectomy in a cat with a laryngeal peripheral nerve sheath tumor.

OBJECTIVE: To report the surgical technique and outcome of total laryngectomy in a single clinical case. STUDY DESIGN: Case report. ANIMAL: A 5-year-old female spayed domestic shorthair cat. METHODS: A cat presented for acute, severe respiratory distress caused by an invasive laryngeal mass. Incisional biopsy was indicative of sarcoma. Computed tomography of head, neck, and thorax was performed revealing no evidence of metastasis. A total laryngectomy and permanent tracheostomy were performed, and the cat could breathe without difficulties immediately postoperatively. Histopathology confirmed a laryngeal low-grade peripheral nerve sheath tumor (PNST). RESULTS: Surgical margins were free of tumor cells. Surgical revision of the tracheostomy stoma due to obstructive granulation tissue was necessary 24 days after the initial surgery. Nine days after revision surgery, the cat was discharged from the hospital. No evidence of local recurrence or metastasis was detected on repeat computed tomography of the head, neck, and thorax at 6 months, nor on chest radiographs at 12 months postoperatively. At the time of writing (13 months postoperatively), the cat is still alive with a good quality of life. CONCLUSION: Total laryngectomy with permanent tracheostomy allowed the complete removal of an obstructive laryngeal PNST and provided a good quality of life in a cat. CLINICAL SIGNIFICANCE: To the authors' knowledge, this case report represents the first detailed description of the surgical procedure and clinical outcome for a total laryngectomy in a cat.

A rare case of malignant vagus nerve sheath tumor presenting with multiple cranial nerve dysfunction in a dog.

A 5-year-old intact male Gascon Saintongeois dog was presented with a 6-month history of coughing, laryngeal paralysis, a deglutition disorder of gradual onset, and left-sided Horner's syndrome. The dog was admitted as an emergency for acute central vestibular signs. Magnetic resonance images identified a left extra-axial brainstem lesion extending caudally from the medulla to the vagosympathetic trunk. Histological and immunohistological examination revealed a high grade epithelioid malignant peripheral nerve sheath tumor (MPNST). This case report is the first description of a MPNST of the vagus nerve compressing the brainstem and causing multiple cranial nerve dysfunction in a dog. Key clinical message: Nerve sheath tumors have been reported in many locations arising from spinal nerve roots and cranial nerves. Although the trigeminal nerve is the most commonly affected nerve, other cranial nerves such as the vagus can be affected.

Un cas rare de tumeur maligne de la gaine du nerf vague à l'origine d'une dysfonction de plusieurs nerfs crâniens chez un chien. Un chien mâle entier de cinq ans de race Gascon Saintongeois a été présenté avec un historique de 6 mois de toux, paralysie laryngée, trouble de la déglutition d'évolution progressive et un syndrome de Claude Bernard Horner à gauche. Le chien a été admis en urgence pour des signes vestibulaires centraux. Une imagerie par résonnance magnétique a mis en évidence une lésion extra-axiale gauche localisée au niveau du tronc cérébral s'étendant caudalement de la medulla vers le tronc vagosympathique. Les examens histologique et immunohistologique ont révélé une tumeur épithéliale maligne des gaines nerveuses de haut grade (TMGN). Ce rapport de cas est la première description de TMGN du nerf vague comprimant le tronc cérébral et à l'origine d'une dysfonction de plusieurs nerfs crâniens chez un chien.Message clinique clé:Les tumeurs des gaines des nerfs ont été rapportées de plusieurs localisations prenant leur origine des racines des nerfs spinaux et des nerfs crâniens. Bien que le nerf trijumeau soit le nerf le plus fréquemment affecté, d'autres nerfs crâniens, tel que le vague, peuvent être affectés.(Traduit par Dr Serge Messier).

Canine Spindle Cell Mammary Tumor: A Retrospective Study of 67 Cases.

Canine spindle cell mammary tumor (CSCMT) is an infrequent canine mammary tumor (CMT) composed of spindle or fusiform cells, which represents a challenge for pathologists and clinicians. Mammary tumors submitted for histopathology from 1998 to 2013 and compatible with CSCMTs were retrospectively selected. The tumors were diagnosed based on the hematoxylin and eosin (HE)-stained section; malignant tumors were graded using a canine soft tissue sarcoma grading scheme and a canine mammary tumor grading scheme, and they were further assigned a diagnosis based on immunohistochemistry (IHC) for pancytokeratin, cytokeratin 14, p63, calponin, vimentin, Ki-67, CD31, desmin, myosin, smooth muscle actin, glial fibrillary acidic protein, and S-100. The origin of the tumors was assessed as mammary, skin, or unknown. The prevalence of CSCMT was 1% of all CMTs. CSCMTs included 3 benign tumors (1 angioma and 2 benign myoepitheliomas) and 67 malignant tumors that after IHC were diagnosed as malignant myoepithelioma (64%), carcinoma and malignant myoepithelioma (19%), hemangiosarcoma (8%), undifferentiated sarcoma (5%), peripheral nerve sheath tumor (3%), and fibrosarcoma (2%). The diagnosis based on the HE-stained section differed from the diagnosis after IHC in 75% of the malignant cases. The majority of malignant CSCMTs were solitary (57%) large tumors (6.42 ± 3.92 cm) with low metastatic potential and high survival rate (8% tumor-related mortality). Higher sarcoma grade was associated with older age (P = .034) and greater tumor size (P = .037). Malignant CSCMTs need to be evaluated by IHC to ensure the histotype and the relatively benign clinical behavior, despite their large size.

High dose hypofractionated frameless volumetric modulated arc radiotherapy is a feasible method for treating canine trigeminal nerve sheath tumors.

The aim of this prospective pilot study was to evaluate the feasibility and effectiveness of curative intent high dose hypofractionated frameless volumetric modulated arc radiotherapy for treatment of canine trigeminal peripheral nerve sheath tumors. Client-owned dogs with a presumptive imaging-based diagnosis of trigeminal peripheral nerve sheath tumor were recruited for the study during the period of February 2010 to December 2013. Seven dogs were enrolled and treated with high dose hypofractionated volumetric modulated arc radiotherapy delivered by a 6 MV linear accelerator equipped with a micro-multileaf beam collimator. The plans were computed using a Monte Carlo algorithm with a prescription dose of 37 Gy delivered in five fractions on alternate days. Overall survival was estimated using a Kaplan-Meier curve analysis. Magnetic resonance imaging (MRI) follow-up examinations revealed complete response in one dog, partial response in four dogs, and stable disease in two dogs. Median overall survival was 952 days with a 95% confidence interval of 543-1361 days. Volumetric modulated arc radiotherapy was demonstrated to be feasible and effective for trigeminal peripheral nerve sheath tumor treatment in this sample of dogs. The technique required few sedations and spared organs at risk. Even though larger studies are required, these preliminary results supported the use of high dose hypofractionated volumetric modulated arc radiotherapy as an alternative to other treatment modalities.

Retrobulbar malignant peripheral nerve sheath tumor in a golden retriever dog: A challenging diagnosis.

A 9-year-old golden retriever dog was diagnosed with a left retrobulbar mass. Fine-needle aspirations and incisional biopsies resulted in discordant diagnoses: myxosarcoma/myxoma or rhadomyosarcoma, respectively. Immunohistochemistry following exenteration allowed definitive diagnosis of malignant peripheral nerve sheath tumor with fibromyxomatous differentiation. Fifteen weeks after surgery, an aggressive recurrence resulted in euthanasia.

Tumeur rétrobulbaire maligne des gaines nerveuses périphériques chez un Golden Retriever : un défi diagnostique. Une masse rétrobulbaire gauche a été diagnostiquée chez une Golden Retriever de 9 ans. Des aspirations à l'aiguille fine et des biopsies incisionnelles ont établi des diagnostics discordants : un myxosarcome/myxome ou un rhabdomyosarcome, respectivement. Suite à l'exentération, l'immunohistochimie a permis un diagnostic définitif de tumeur maligne des gaines nerveuses périphériques avec différenciation fibro-myxomateuse. Quinze semaines après la chirurgie, une récidive agressive a conduit à l'euthanasie de la chienne.(Traduit par les auteurs).

Primary bilateral corneal nerve sheath neoplasm in a dog.

A 15-year-old, neutered male, Shih Tzu cross developed progressive corneal stromal thickening and vascularization of the right eye, and 5 months later, of the left eye. Both eyes became blind due to extensive corneal opacification and were enucleated. Light microscopic examination revealed a diffuse corneal infiltrate of neoplastic mesenchymal cells, and immunohistochemistry revealed diffuse cytoplasmic vimentin immunoreactivity and variable cytoplasmic and nuclear immunoreactivity for S100 in the neoplastic cells. Transmission electron microscopy revealed desmosomes between contiguous cells, thread-like cytoplasmic processes coated with basement membrane, extracellular bundles of collagen, and axonal degeneration consistent with features of a nerve sheath neoplasm. This is the first report of primary, bilateral corneal nerve sheath sarcoma in a canine.

Clinical and imaging findings, treatments, and outcomes in 27 dogs with imaging diagnosed trigeminal nerve sheath tumors: A multi-center study.

The clinical behavior of canine trigeminal nerve sheath tumors and benefits of previously reported treatments are incompletely defined. Aims of this retrospective, multicenter, observational study were to describe clinical signs, tumor localization characteristics, treatments, and clinical outcomes in a group of dogs with this neoplasm. Databases at four hospitals were reviewed for dogs with a trigeminal nerve sheath tumor diagnosis, magnetic resonance imaging (MRI) studies, and presentation between 2004 and 2014. A single observer recorded medical record findings and two observers recorded MRI characteristics by consensus. A total of 27 dogs met inclusion criteria (15 treated with stereotactic radiation therapy and 12 unirradiated). Two unirradiated dogs were excluded from outcome analyses. The most common presenting signs were masticatory muscle atrophy (26 dogs), neurologic signs referable to intracranial disease (13), and ocular disease (12). Based on MRI findings, all dogs had disease extending centrally at the level of the brainstem. The most commonly affected trigeminal nerve branches were the mandibular (26 dogs), maxillary (22), and ophthalmic (10). Of 15 dogs treated with stereotactic radiation therapy, one had improved muscle atrophy, and six had poor ocular health after treatment. Neurologic signs improved in 4/5 dogs with intracranial signs. Overall median survival time for the 10 unirradiated dogs with available follow-up was 12 days and 441 days for the 15 stereotactic radiation therapy dogs. Mean survival times between these groups were not significantly different (mean 95% CI for unirradiated dogs was 44-424 days and mean 95% CI for stereotactic radiation therapy dogs was 260-518 days).

Retrobulbar pigmented peripheral nerve sheath tumor in a dog.

A 1-year-old male castrated Pug was referred for unilateral exophthalmos unresponsive to oral antibiotic and anti-inflammatory therapy. Clinical findings included exophthalmos of the left eye with lateral strabismus, resistance to retropulsion, and an elevated nictitans. Hematologic and biochemical analyses were within normal limits. Findings following computed tomography (CT) of the head included an expansile retrobulbar soft tissue mass with bony lysis extending into the left nasal cavity and nasopharynx. Ultrasound-guided fine-needle aspirates and biopsy samples obtained via rhinoscopy were nondiagnostic. Palliative exenteration was elected; the patient was euthanized 13 weeks following exenteration due to development of neurologic signs and perceived poor quality of life. The histopathologic diagnosis was a malignant pigmented peripheral nerve sheath tumor.

IMAGING DIAGNOSIS - UNILATERAL TRIGEMINAL NEURITIS MIMICKING PERIPHERAL NERVE SHEATH TUMOR IN A HORSE.

A 16-year old Warmblood gelding presented with a nonhealing corneal ulcer and absent corneal sensation in the left eye. A lesion affecting the maxillary and ophthalmic branches of the left trigeminal nerve was suspected. Magnetic resonance (MR) imaging identified marked thickening of the ophthalmic and maxillary branches of the left trigeminal nerve. The nerve was iso- to hypointense on T1-weighted and T2-weighted images with heterogeneous enhancement. A peripheral nerve sheath tumor was suspected, however granulomatous neuritis was histopathologically confirmed. These inflammatory changes can result in severe nerve enlargement and should be considered with MR findings suggestive of peripheral nerve sheath tumor.

Benign Peripheral Nerve Sheath Tumor in a Wild Toco Toucan ( Ramphastos toco ).

Peripheral nerve sheath tumors are a heterogeneous group of neoplasms that comprise neurofibromas, schwannomas, neurilemmomas, and perineuromas. In animals, peripheral nerve sheath neoplasms are most commonly diagnosed in dogs and cattle, followed by horses, goats, and cats, but their occurrence is uncommon in birds. An adult, free-living, male toco (common) toucan ( Ramphastos toco ) was admitted to the zoo animal clinic with weight loss, dehydration, and presence of a soft nodule adhered to the medial portion of the left pectoral muscle. Clinical, cytologic, and computed tomography scan results were indicative of a neoplasm. The toucan died during surgical resection of the mass. Necropsy, histopathologic, and immunohistochemical findings confirmed the diagnosis of benign peripheral nerve sheath tumor. To our knowledge, benign peripheral nerve sheath tumor has not previously been reported in a toucan or any other species in the order Piciformes.

Malignant uveal schwannoma with peripheral nerve extension in a 12-week-old color-dilute Labrador Retriever.

The formalin-fixed, amber-colored right globe from a 12-week-old female silver Labrador Retriever dog was submitted to the Comparative Ocular Pathology Laboratory of Wisconsin for light microscopic evaluation. The clinical history described a collapsed anterior chamber and multifocal nodular lesions in the peripheral iris. Histologically, immunohistochemically, and ultrastructurally, the uveal mass was consistent with a malignant schwannoma; there was extension along peripheral nerves within the sclera. The signalment and behavior of the neoplasm distinguish it from the uveal schwannoma of blue-eyed dogs and bear some resemblance to the ocular lesions in human neurofibromatosis. The dilute color mutation may contribute to the cause. Six weeks later, the dog did not develop any additional masses.

Lingual Malignant Peripheral Nerve Sheath Tumor in a Chinese Pug Dog.

A 9-year-old spayed/female Chinese Pug dog presented for evaluation of a mass located on the rostral aspect of the tongue. An incisional biopsy was acquired, submitted, and interpreted as a possible granular cell tumor based on hematoxylin and eosin, and periodic acid Schiff histopathologic staining characteristics. The diagnosis was supported by immunohistochemical evaluation that was positive for S-100, vimentin, and neuron-specific enolase. Based on the absence of mitotic figures in the incisional biopsy, a partial glossectomy was performed with gross margins of at least 1-cm. The excisional biopsy revealed significant features of malignancy, with neoplastic cells in close association with peripheral nerves, consistent with malignant peripheral nerve sheath tumor. Tumor-free margins were obtained, and the glossectomy had expected healing with no recurrence apparent 6-months following surgery.

Peripheral nerve sheath tumor in a subadult golden eagle (Aquila chrysaetos).

A 5-year-old, female golden eagle (Aquila chrysaetos) was admitted with tetraplegia that progressed to a nonambulatory, spastic tetraparesis after a few days of treatment. Clinical and radiologic examinations, including radiography, computed tomography scan, and myelography, were indicative of neoplasia involving a spinal nerve root. Postmortem magnetic resonance imaging and necropsy findings confirmed the diagnosis of a peripheral nerve sheath neoplasia, not, to our knowledge, previously reported in a raptor.

A retrospective study on subcutaneous malignant peripheral nerve sheath tumors in 14 domestic rabbits (Oryctolagus cuniculus) treated surgically between 2008 and 2021.

A retrospective study involving 14 pet rabbits histopathologically diagnosed with malignant peripheral nerve sheath tumors (MPNSTs) was conducted. The age at diagnosis was 4-12 years, with a median age of 8.6 years. All rabbits had solid subcutaneous tumor masses in varied locations. Surgical excision of the tumors was performed in all cases. Recurrence was observed in 10 cases (71%), and postoperative metastasis to the lung was suspected in 4 cases (29%). The postoperative mean and median survival times were 11 months and 9 months, respectively. Hence, MPNSTs should be considered in the differential diagnosis for subcutaneous masses in rabbits and it is essential to inform the owners of the potentially high recurrence and metastasis rates.

Cardiac tumor comprising a malignant peripheral nerve sheath tumor and spontaneous atrial osseous metaplasia in a sheep.

Primary cardiac tumors in animals are very rare. The purpose of this report was to describe the first case of a cardiac tumor comprising a malignant peripheral nerve sheath tumor and spontaneous atrial osseous metaplasia in a Corriedale sheep. Histologically, the tumor in the bilateral atrial pericardium consisted of dense cellular components comprising tumor cells and a sparse cellular area, and non-neoplastic mature bone tissue. The tumor cells were spindle-shaped, round, or polygonal, and proliferating, with fascicular, storiform, palisading, and sheet patterns. Immunohistochemically, the tumor cells were positive for vimentin, S-100, occasionally positive for myeline basic protein, glial fibrillary acidic protein, neurofilament, neuron specific enolase, and neuron growth factor receptor suggesting that they originated from the nervous system. On the basis of these findings, the final diagnosis was a malignant peripheral nerve sheath tumor and spontaneous atrial osseous metaplasia.

Malignant peripheral nerve sheath tumor in the kidney of a dog.

A 12-year-old castrated male poodle presented with vomiting and diarrhea. Ultrasonography and computed tomography revealed a protruding mass at the caudal pole of the left kidney. Grossly, the poorly circumscribed abnormal mass was 1.6 × 1.8 × 1.9 cm in size and had multifocal dark-red foci. Microscopically, it was composed of densely or loosely packed variable-sized short spindle or ovoid cells. These neoplastic cells showed high pleomorphism, mitotic figures, and invasive tendency to the adjacent tissue. Immunohistochemically, the neoplastic spindle cells expressed vimentin, S100, neuron-specific enolase, nerve growth factor receptor, and laminin. Therefore, the mass was diagnosed as a malignant peripheral nerve sheath tumor (MPNST). To our knowledge, this is the first report of primary renal MPNST in a dog.