Magnetic resonance imaging features of feline intracranial neoplasia: retrospective analysis of 46 cats

Intracranial meningioma in two coeval adult cats from the same litter

Case summary

In this report we describe the occurrence of intracranial meningioma in two adult cats from the same litter. The location of the meningioma varied: one tumour was at the level of the brainstem, and the other was affecting the temporal and piriform lobes. The cat with the brainstem meningioma was treated with radiotherapy and the littermate had a rostrotentorial craniectomy for tumour removal. Both cats had a histopathological diagnosis of grade I meningioma of a predominantly fibrous subtype.

Relevance and novel information

Cases of familial meningioma in cats have not previously been described in the veterinary literature. However, familial meningioma is well described in humans and it is possible that cases are underestimated in animals. We discuss the possible genetic background and other causes, as well as challenges we may face in veterinary medicine in identifying these associations.

Comparison of Canine and Feline Meningiomas Using the Apparent Diffusion Coefficient and Fractional Anisotropy

Meningiomas are the most common intracranial tumor in dogs and cats, and their surgical resection is often performed because they are present on the brain surface. Typical meningiomas show comparatively characteristic magnetic resonance imaging findings that lead to clinical diagnosis; however, it is necessary to capture not only macroscopic changes but also microstructural changes to devise a strategy for surgical resection and/or quality of removal. To visualize such microstructural changes, diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) have been used in human medicine. The aim of this retrospective study was to investigate the different characteristics of the apparent diffusion coefficient (ADC) from DWI and fractional anisotropy (FA) from DTI of meningioma between dogs and cats. Statistical analyses were performed to compare ADC and FA values between the intratumoral or peritumoral regions and normal-appearing white matter (NAWM) among 13 dogs (13 lesions, but 12 each in ADC and FA analysis) and six cats (seven lesions). The NAWM of cats had a significantly lower ADC and higher FA compared to dogs. Therefore, for a comparison between dogs and cats, we used ADC and FA ratios that were calculated by dividing the subject (intra- or peritumoral) ADC and FA values by those of NAWM on the contralateral side. Regarding the intratumoral region, feline meningiomas showed a significantly lower ADC ratio and higher FA ratio than canine meningiomas. This study suggested that ADC and FA may be able to distinguish a meningioma that is solid and easy to detach, like as typical feline meningiomas.

Incidence and type of brain herniation associated with intracranial meningioma in dogs and cats

The incidence of brain herniation (BH) in association with intracranial meningioma (ICM) in dogs and cats is poorly described. The aim of this study was to evaluate the rate and type of brain herniations in client-owned dogs and cats with ICMs and to determine the meningioma volume (MV) relative to cranial cavity volume (CCV). A retrospective magnetic resonance imaging (MRI) analysis study of 24 cats and 45 dogs with ICMs was conducted to ascertain the presence and characteristics of BH. MV and CCV were measured and their ratio was calculated for each animal. Correlations of MV/CCV with independent variables were analyzed. BH was encountered in 24/24 cats (100%) and 30/45 dogs (66.7%) with ICMs. In cats, the most frequent presentation was foramenal herniation (FMH; 23/24, 95.8%), followed by caudotentorial (CTH; 21/24, 87.5%) and subfalcine (SH; 18/24, 75.0%) herniation. In dogs, the most frequent presentation was SH (28/45; 62.2%), followed by CTH (9/45; 20%) and FMH (2/45; 4.4%). Relative to dogs, cats with ICM had greater incidences of FMH (P<0.001) and CTH (P<0.001). Mean MV/CCV ratio was higher in cats (0.098) than in dogs (0.038; P<0.001). The most common clinical sign of ICM was altered behavior in cats (43%, P<0.01) and seizures in dogs (74.4%, P<0.001). In conclusion, cats were found to be more likely than dogs to present FMH and CTH, with a proportionally greater neoplasia volume.

Diagnosis and clinical outcome following surgical resection of an intracranial grade III anaplastic gemistocytic astrocytoma in a cat

CASE SUMMARY

A 10-year-old Maine Coon cat was presented for acute onset seizures and cerebrothalamic signs. An intracranial mass, suspected to be a meningioma, was diagnosed on MRI and surgically excised. Histopathology appeared consistent with an atypical meningioma. However, following rapid regrowth of the neoplasm, the patient was humanely euthanized 3 months later. On post-mortem histopathology, the neoplasm was diagnosed as a grade III anaplastic gemistocytic astrocytoma.

RELEVANCE AND NOVEL INFORMATION

Gemistocytic astrocytomas are rare brain tumors in the feline patient. This case represents the first report of a feline grade III anaplastic gemistocytic astrocytoma in the cerebrum of a cat with surgical excision and recurrence. The challenging nature of ante-mortem diagnosis and the guarded prognosis, despite surgical intervention, are presented in this report.

Feline meningioma with extensive nasal involvement

Case summary

A 9-year-old male neutered domestic longhair cat was presented with a 3 week history of lethargy and pain of unknown origin. A large extra-axial mass was demonstrated on MRI of the head, with cribriform plate destruction, extensive nasal invasion and intracranial expansion, producing a severe mass effect. The mass was isointense on T1-weighted imaging, predominantly hypointense with some hyperintense areas on T2-weighted imaging and fluid attenuation inversion recovery, markedly contrast enhancing, and caused transtentorial and cerebellar herniation. Histopathological evaluation confirmed a transitional (mixed) meningioma.

Relevance and novel information

To our knowledge this is the first report of a meningioma with extensive nasal involvement in a cat. Based on this case, meningioma should be considered as a differential diagnosis for tumours involving the nasal cavity and frontal lobe with cribriform plate destruction.

Neurolymphomatosis caused by T-cell lymphosarcoma in a cat: imaging description and treatment review

Case summary

A 16-year-old domestic shorthair cat was evaluated for acute-onset right pelvic limb monoparesis localized to the sciatic nerve. MRI revealed a homogeneously contrast-enhancing, well-demarcated mass effacing the right sciatic nerve from its intravertebral origin to the end of the viewable field (mid-femur). Abdominal ultrasound revealed thickened small intestinal loops and enlarged mesenteric lymph nodes. Cytology of the small intestine was suggestive of lymphosarcoma. T-cell lymphosarcoma of the sciatic nerve and small intestines was confirmed with incisional biopsy. Treatment consisted of systemic chemotherapy with vincristine followed by the Wisconsin–Madison feline lymphosarcoma protocol, but despite treatment the patient neurologically worsened and was euthanized after 54 days.

Relevance and novel information

We present herein one of the first descriptions of neurolymphomatosis in the domestic cat that included post-intravenous contrast MRI. Treatment options based on recommendations for people with neurolymphomatosis include systemic chemotherapy, intrathecal chemotherapy and/or localized radiation chemotherapy. The authors recommend that all cats be screened for concurrent non-neuronal areas of lymphosarcoma before undergoing treatment for neurolymphomatosis, regardless of clinical signs.

Clinical and magnetic resonance imaging findings of a cerebellar medulloblastoma in a heifer

Reports of medulloblastoma in cattle are scarce; however, this neoplasm should be included as a differential diagnosis in cases of cerebellar or central vestibular signs in young cattle. The MRI appearance of the medulloblastoma reported here, previously unreported in cattle, consisted of a T1-weighted hypointense and T2-weighted heterogeneously hyperintense intra-axial mass.

Invasive nasal histiocytic sarcoma as a cause of temporal lobe epilepsy in a cat

Case summary

A 10-year-old neutered female domestic shorthair cat was presented with an acute onset of neurological signs suggestive of a right-sided forebrain lesion, temporal lobe epilepsy and generalised seizure activity. MRI of the head revealed an expansile soft tissue mass in the caudal nasal passages (both sides but predominantly right-sided) involving the ethmoid bone and extending through the cribriform plate into the cranial vault affecting predominantly the right frontal lobe and temporal lobe. Histopathological examination of the tumour revealed a histiocytic sarcoma.

Relevance and novel information

This is the first report of a cat with clinical signs of temporal lobe epilepsy due to an invasive, histiocytic sarcoma. Histiocytic sarcoma, although rare, should be included in the list of differential diagnoses for soft tissue masses extending through the cribriform plate. Other differential diagnoses are primary nasal neoplasia (eg, adenocarcinoma, squamous cell carcinoma, chondrosarcoma and other types of sarcomas), lymphoma and olfactory neuroblastoma. Temporal lobe epilepsy in cats can be the consequence of primary pathology of temporal lobe structures, or it can be a consequence of pathology with an effect on these structures (eg, mass effect or disruption of interconnecting neuronal pathways).

Supratentorial arachnoid cyst management by cystoperitoneal shunt in a 1-year-old European cat

Arachnoid cysts are defined as an accumulation of fluid within the arachnoid membrane. Feline intracranial arachnoid cysts are seldom reported, with only three cases in the veterinary literature. A 1-year-old male neutered European cat with a 24 h history of seizures was presented to the small animal neurology department at Vetagro Sup, Lyon. Magnetic resonance imaging (MRI) revealed a large intracranial arachnoid cyst ventral to the brain in the left temporal area. Cystoperitoneal shunt placement resulted in complete resolution of the cyst without recurrence (follow-up MRIs 3 weeks and 21 months after surgery). Anticonvulsant treatment (phenobarbital 2.5 mg/kg q12h) was initiated at presentation and gradually stopped after 17 months. Seizures recurred 4 months after ending treatment, and seizure therapy was therefore restarted at the initial dose. We report a case of an intracranial arachnoid cyst in an unusual location not previously described. A cystoperitoneal shunt resolved the cyst without complications. Maintenance anticonvulsant treatment was required to control symptomatic epilepsy.

Advances in diagnostic and treatment modalities for intracranial tumors

Intracranial neoplasia is a common clinical condition in domestic companion animals, particularly in dogs. Application of advances in standard diagnostic and therapeutic modalities together with a broad interest in the development of novel translational therapeutic strategies in dogs has resulted in clinically relevant improvements in outcome for many canine patients. This review highlights the status of current diagnostic and therapeutic approaches to intracranial neoplasia and areas of novel treatment currently in development.

Agreement between low-field MRI and CT for the detection of suspected intracranial lesions in dogs and cats

OBJECTIVE

To assess the agreement between CT and MRI for enabling detection of intracranial lesions in cats and dogs.

DESIGN

Evaluation study.

ANIMALS

51 dogs and 7 cats with suspected intracranial lesions.

PROCEDURES

During a 2-year-period, dogs and cats with suspected intracranial pathological changes underwent MRI and CT (single slice) of the head. Radiologists evaluated images produced with both techniques without awareness of subject identity. Agreement between methods was assessed for allowing detection of solitary or multiple lesions, selected lesion characteristics (via the Cohen κ statistic), and lesion dimensions (via Bland-Altman plots).

RESULTS

CT and MRI had substantial agreement for allowing detection of lesions and identification of whether the lesions were solitary or multiple. The techniques agreed almost perfectly for allowing identification of a mass effect and contrast medium enhancement, which were considered principal diagnostic imaging signs. A lower degree of agreement was attained for allowing identification of enhancement patterns and aspects of lesion margins. Agreement was substantial to almost perfect for lesion visualization in most anatomic brain regions but poor for identification of lesion dimensions.

CONCLUSIONS AND CLINICAL RELEVANCE

Degrees of agreement between CT and MRI for allowing the detection and characterization of intracranial lesions ranged from poor to almost perfect, depending on the variable assessed. More investigation is needed into the relative analytic sensitivity and possible complementarities of CT and MRI in the detection of suspected intracranial lesions in dogs and cats.

Correlating magnetic resonance findings with neuropathology and clinical signs in dogs and cats

The histologic characteristics that are the basis for diagnosis of central nervous system conditions cannot be visualized directly using magnetic resonance (MR) methods, but clinical diagnosis may be based on the frequency and pattern of MR imaging signs, which represent predominantly the gross morphologic features of lesions. Additional quantitative MR measures of myelination, cell swelling, gliosis, and neuronal loss may also be used for more specific characterization of lesions. These measures include magnetization transfer ratio, apparent diffusion coefficient, and the concentrations or ratios of metabolites identified by spectroscopy. Confidence that an MR abnormality is responsible for the clinical signs depends primarily on the degree of correspondence between the site of the lesion and the neuroanatomical localization.

Cerebral Blastomyces dermatitidis infection in a cat

CASE DESCRIPTION

An 8-year-old domestic shorthair cat was evaluated because of signs of depression, circling, and visual deficits.

CLINICAL FINDINGS

The cat had no cutaneous lesions, and results of an ophthalmologic examination and thoracic radiography were within reference limits. Computed tomography of the brain revealed a mass lesion involving the right parietal, temporal, and occipital lobes; the mass was in broad-based contact with the skull and smoothly marginated and had strong homogenous enhancement after contrast agent administration. During craniectomy, samples of the mass were collected for cytologic and histopathologic evaluations and microbial culture. A diagnosis of Blastomyces dermatitidis-associated meningoencephalitis with secondary pyogranulomatous inflammation was made.

TREATMENT AND OUTCOME

Amphotericin B (0.25 mg/kg [0.11 mg/lb], IV) was administered on alternate days (cumulative dose, 1.75 mg/kg [0.8 mg/lb]). To minimize the risk of nephrotoxicosis, assessments of serum biochemical variables (urea nitrogen and creatinine concentrations) and urinalyses were performed at intervals. The third dose of amphotericin B was postponed 48 hours because the cat became azotemic. The cat subsequently received fluconazole (10 mg/kg [4.5 mg/lb], PO, q 12 h) for 5.5 months. Six months after discontinuation of that treatment, the cat appeared healthy and had no signs of relapse.

CLINICAL RELEVANCE

Brain infection with B dermatitidis is typically associated with widespread disseminated disease. The cat of this report had no evidence of systemic disease. Blastomycosis of the CNS should be considered as a differential diagnosis for brain lesions in cats from areas in which B dermatitidis is endemic.

IMAGING DIAGNOSIS?HYPEROSTOSIS ASSOCIATED WITH MENINGIOMA IN A DOG

A 5-year-old neutered male Beagle mix dog had a 5-day history of generalized tonic-clonic seizures. Before the seizures, the dog had a 1-2-month history of progressive right hemiparesis. In computed tomography images, a presumed extraaxial mass with hyperostosis and destruction of the skull covering the mass were identified. Surgical excision was performed and the histopathologic diagnosis was meningioma. Hyperostosis is frequently associated with feline meningioma, but this report documents that hyperostosis may also occur secondary to meningioma in the dog.

Clinical and magnetic resonance imaging features of nasopharyngeal lymphoma in two cats with concurrent intracranial mass

Lymphoma is reported to be the most common nasal and second most common intracranial neoplasm in cats. Intracranial lymphoma may occur as a primary central nervous system lymphoma or as part of multi-centric disease. Two cats were presented with histopathologically confirmed nasopharyngeal lymphoma and concurrent mass within the middle fossa of the cranial cavity, with magnetic resonance imaging suggestive of direct communication. Both cats demonstrated evidence of bilateral oculomotor nerve deficits and upper respiratory tract noise. In one cat, bilateral optic nerve deficits were also present. The magnetic resonance imaging features were similar in both cases and demonstrated a contrast-enhancing intracranial mass on the ventral aspect of the middle fossa of the cranial cavity and an adjacent mass arising from the dorsal aspect of the nasopharynx. Lymphoma should be included as an important differential diagnosis in cats presented with middle cranial fossa syndrome (in particular ophthalmoplegia) and stertor.

Comparison of fluid-attenuated inversion recovery and T2-weighted magnetic resonance images in dogs and cats with suspected brain disease

To compare fluid-attenuated inversion recovery (FLAIR) and T2-weighted magnetic resonance (MR) imaging in small animal patients with suspected brain disease, paired sets of FLAIR and T2-weighted MR images of 116 dogs and cats were reviewed separately without any patient information. Images were rated as normal or abnormal using a five-point scale, and the distribution, signal intensity, and anatomic location of abnormalities were recorded. In 60 animals, both FLAIR and T2-weighted images were normal. In 50 animals, the same abnormalities were identified in both FLAIR and T2-weighted images. Overall, very good agreement was found between FLAIR and T2-weighted MR images (kappa = 0.88). FLAIR images had abnormalities that were not recognized in the corresponding T2-weighted images in six of 116 examinations (5%). In four of these, the abnormalities in FLAIR images were thought to represent pathology, including granulomatous meningoencephalitis in one dog, postictal edema in one dog, and undiagnosed lesions in two dogs. In the remaining two examinations, the abnormalities in FLAIR images were probably artifacts. No examples were found of intracranial abnormalities in T2-weighted images that were not visible in FLAIR images. In this study, acquiring FLAIR images in addition to T2-weighted images resulted in detection of otherwise occult abnormalities in relatively few patients.