IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA

A 13‐year‐old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill‐defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill‐defined, irregular, hypoechoic, intramuscular nodules.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING FINDINGS OF AN INTRACRANIAL EPIDURAL TUBERCULOMA IN A DOG

Magnetic resonance (MR) imaging is highly sensitive for detecting tuberculomas in human patients but the specificity of the MR imaging features is low. Misdiagnosis with intracranial neoplasia is common, especially with dural‐based lesions or lesions located in the epidural space. We describe the MR imaging characteristics of an intracranial epidural tuberculoma caused by Mycobacterium tuberculosis infection in a dog. The intracranial mass and skull flat bone lysis and erosion are similar to those described in human caseating tuberculomas and can mimic intracranial neoplastic disease.     

IMAGING DIAGNOSIS—HETEROBILHARZIA AMERICANA INFECTION IN A DOG

An approximately three‐year‐old mixed breed female dog was evaluated for peritoneal effusion, anorexia, intermittent vomiting, and diarrhea. Radiographically, there was mineralization of the wall of small intestinal segments. Sonographic findings were consistent with multisystemic mineralization of liver, small intestinal wall, and pancreas. Multifocal granulomas containing schistosome eggs (Heterobilharzia americana) were identified histologically. The mineralization pattern described herein is an uncommon presentation of severe diffuse heterobilharziasis in a dog.     

IMAGING DIAGNOSIS—DISSEMINATED PERITONEAL LEIOMYOMATOSIS IN A DOG

A 17‐month‐old male Labrador retriever presented for evaluation of an abdominal mass felt during abdominal palpation. Multiple variably sized cystic masses were identified on sonographic and radiographic images. Exploratory laparotomy revealed multiple peritoneal masses that exhibited atypical contractions and lacked an identifiable organ of origin. Histology and immunohistochemistry of multiple surgically excised masses was consistent with benign tumors of smooth muscle origin (leiomyomas). The presence of multiple peritoneal leiomyomas in this dog is consistent with disseminated peritoneal leiomyomatosis. Two years after diagnosis and multiple surgical interventions, continual insidious enlargement of leiomyomas was identified on ultrasound and CT.     

IMAGING DIAGNOSIS—CONGENITAL LOBAR EMPHYSEMA IN A DOG

A 14‐week‐old female West Highland White Terrier developed acute dyspnea. Radiographically there was an enlarged, hyperlucent caudal portion of the left cranial lung lobe and a diffuse, severe interstitial‐to‐alveolar pattern in the remaining lung lobes that was accentuated caudodorsally. Computed tomography confirmed the presence of the emphysematous lobe and further showed it to have focal lobar bronchial collapse. Lung lobe resection was performed, and the diagnosis was congenital lobar emphysema secondary to bronchial cartilage hypoplasia.     

IMAGING DIAGNOSIS—THROMBOSED ORBITAL VARIX IN A DOG

A 9‐week‐old female Rhodesian Ridgeback presented with exophthalmos following minor blunt trauma to the left orbital area. Ocular ultrasound showed an extraconal retrobulbar mass ventromedial to the left globe. Magnetic resonance (MR) imaging demonstrated a thrombosed orbital vascular malformation without intracranial extension. Doppler ultrasound features of nonpulsatile slow flow were consistent with an orbital varix. Contrast‐enhanced dynamic time‐resolved and high‐resolution MR angiography demonstrated the varix arose from the anastomotic branch of the dorsal and ventral external ophthalmic veins. Conservative management led to a positive outcome defined as a visual eye and nearly normal cosmetic appearance at 8‐month follow‐up.     

IMAGING DIAGNOSIS—SPINAL CORD HISTIOCYTIC SARCOMA IN A DOG

A 12‐year‐old mixed breed dog was presented for evaluation of progressive paraparesis and ataxia. Magnetic resonance (MR) imaging was performed and identified multifocal intradural spinal cord mass lesions. The lesions were hyperintense in T2‐weighted sequences, isointense to mildly hyperintense in T1‐weighted sequences with strong contrast enhancement of the intradural lesions and spinal cord meninges. Spinal cord neoplasia was suspected. A diagnosis of intramedullary spinal cord histiocytic sarcoma, confined to the central nervous system, was confirmed histopathologically. Spinal cord histiocytic sarcoma is a rare neoplasm, but should be included in the differential diagnosis for dogs with clinical signs of myelopathy.     

IMAGING DIAGNOSIS—METASTATIC HEMANGIOSARCOMA CAUSING CEREBRAL HEMORRHAGE IN A DOG

A 9-year-old male Appenzeller mountain dog had progressive severe ataxia and central vestibular syndrome that was localized clinically to the brain stem. The cerebrospinal fluid characteristics were suggestive of hemorrhage into the subarachnoid space. On computed tomography (CT), hyperattenuating masses were found in the left lateral ventricle extending into the cerebrum, and another involving the cerebellum and brainstem. The hyperattenuation of the masses in noncontrast images and the absence of contrast enhancement were consistent with hemorrhage. The dog underwent euthanasia. A metastatic hemangiosarcoma in the brain, causing acute bleeding in the left lateral ventricle and the brainstem, was found. A solitary mass in the left myocardium was thought to be the primary site. CT characteristics of intracranial hemorrhage are reviewed.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING FEATURES OF A CEREBRAL HEMANGIOBLASTOMA IN A DOG

The magnetic resonance (MR) imaging features of a cerebral hemangioblastoma in a 9‐year‐old dog are described. Imaging revealed a well‐defined contrast‐enhancing lesion of the rostral forebrain that appeared extraparenchymal. Histopathology of the excised mass showed clusters of small blood vessels interspersed with interstitial cells staining positive for neuronal specific enolase, features consistent with a cerebral hemangioblastoma; the mass also appeared intraparenchymal after further immunohistochemistry study. This neoplasm should be considered a rare differential diagnosis for intracranial masses in dogs.     

IMAGING DIAGNOSIS—SPINAL CORD HEMANGIOMA IN TWO DOGS

Intramedullary masses are a dilemma due to the limited access for a nonsurgical biopsy, thus, accurate imaging characterization is crucial. Magnetic resonance imaging findings of two confirmed canine thoracic intramedullary hemangiomas are described. A capillary hemangioma was of mixed intensity but predominantly T2‐hyperintense and mildly T1‐hyperintense to spinal cord with strong contrast enhancement. A cavernous hemangioma had a target‐like appearance in both T1‐weighted (T1w) and T2‐weighted (T2w) images. In T2w images there was a small isointense center surrounded by a relatively large hyperintense area. In T1w images, there was a large isointense centre with a relatively small hyperintense periphery. Such characteristics should prioritize hemangioma as a consideration in a progressive myelopathy due to an intramedullary mass.     

IMAGING DIAGNOSIS—SPINAL CORD CHONDROSARCOMA ASSOCIATED WITH SPIROCERCOSIS IN A DOG

A 7‐year‐old neutered female Boerboel cross was examined for progressive left pelvic limb lameness. There was no left patellar reflex but the remaining pelvic limb reflexes were hyperreflexic. Radiographically, there was a poorly mineralized opacity occupying the intervertebral foramen at L4–L5. On computed tomography images there was a hyperattenuating intramedullary lesion at L4–L5 that continued caudally, lateralized to the left and became extramedullary, terminating at L5–L6. In addition, well marginated, hyperattenuating lesions were noted at two muscular sites. The dog underwent euthanasia and a caudal esophageal mass was found at post mortem examination. The tumors in the spinal cord, the esophagus, and the skeletal muscles were diagnosed histologically as low‐grade chondrosarcoma undergoing endochondral ossification. Spirocerca lupi‐induced esophageal chondrosarcoma was believed to be the primary site from which the other, presumably metastatic, lesions originated.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING FEATURES OF METASTATIC CEREBRAL LYMPHOMA IN A DOG

We describe histopathologically confirmed intracranial metastasis of cutaneous lymphoma. In magnetic resonance (MR) images there was a heterogeneous, contrast‐enhancing, extraaxial mass in the right parietal and piriform lobes at the level of the optic chiasm. Our MR imaging findings are consistent with reports in humans in that lymphoma masses have indistinct borders that are iso‐ to hyperintense relative to adjacent gray matter on T2‐weighted images. Our report varies from findings in humans in that the mass was extraaxial, whereas masses reported in humans are intraaxial. Contrast enhancement can be heterogeneous, as in our report, or homogeneous.     

IMAGING DIAGNOSIS—MRI CHARACTERISTICS OF A FOURTH VENTRICULAR CHOLESTEROL GRANULOMA IN A DOG

A 2‐year‐old male American Bulldog experienced paroxysmal staggering, altered consciousness, and hyperesthesia. Magnetic resonance (MR) imaging enabled recognition of a fourth ventricular mass causing compression of the cerebellum and brainstem and obstructive hydrocephalus. The mass was uniformly T2‐hyperintense and predominantly T1‐hypointense. A fluid line was evident on the fluid‐attenuated inversion recovery images. A thin rim of contrast enhancement was noted. Histopathologic diagnosis was a cholesterol granuloma. We were unable to identify any other reports of a cholesterol granuloma residing in the fourth ventricle of a dog. This case report documents the clinical, diagnostic imaging, and histopathologic findings of a canine intracranial cholesterol granuloma. © 2012 Veterinary Radiology & Ultrasound.     

IMAGING DIAGNOSIS—ENDOMETRIAL MINERALIZATION IN A DOG

A 9‐year‐old intact female mixed breed dog was presented for mammary gland tumor surgery, and preoperative radiographs showed a tubular soft tissue opacity mass with multifocal mineralization in the caudoventral abdominal cavity. Subsequent ultrasonography demonstrated uterine dilation with echogenic fluid and endometrial acoustic shadowing consistent with mineralization. Resection of mammary gland tumors and ovariohysterectomy were performed. Pyometra was diagnosed on cytologic examination of uterine fluid. Histopathology of the uterine tissue confirmed a diagnosis of cystic endometrial hyperplasia with uterine mineralization.     

IMAGING DIAGNOSIS—MENINGOENCEPHALITIS SECONDARY TO SUPPURATIVE RHINITIS AND MENINGOENCEPHALOCELE INFECTION IN A DOG

Nasal encephaloceles (meningoceles or meningoencephaloceles) are rare and not reported to be infected or coupled with a facial deformity in dogs. This report describes an older dog with acute worsening of seizures due to suppurative meningoencephalitis with coexisting suppurative rhinitis and infection of a meningoencephalocele. Additionally, the dog had a facial deformity for at least 5 years. The results of necropsy, computed tomography, and postmortem magnetic resonance imaging are compared. The development of nasal encephaloceles is discussed, including the potential role of early trauma, and whether separation of neural ectoderm from the surface ectoderm is part of the pathogenesis.     

IMAGING DIAGNOSIS—BILATERAL ORTHOTOPIC URETEROCELES IN A DOG

A 5‐year‐old neutered male Akita had a 5‐month history of hematuria. Bilateral orthotopic ureteroceles were diagnosed using a combination of sonography, computed tomography (CT), and radiography. With CT excretory urography, the ureteroceles appeared as two intraluminal cystic structures in the vesicoureteral region of the urinary bladder, which directly communicated with dilated ureters. Unlike the other imaging modalities CT excretory urography provided a definitive diagnosis by confirming the communication between the hydroureters and the cystic dilations in the caudodorsal aspect of the urinary bladder.     

IMAGING DIAGNOSIS–SCLEROSING ENCAPSULATING PERITONITIS IN A DOG

An approximately 5‐month‐old American Staffordshire terrier was presented with a history of recurrent peritoneal effusion. Abdominal radiographs and ultrasound showed a loculated effusion in the ventral abdomen with dorsal displacement of abdominal organs, hepatomegaly and rounding of liver and splenic margins. Computed tomography demonstrated centrally located gastrointestinal segments surrounded by a thin soft tissue band and a thickened peritoneal lining. At necropsy a fibrous membrane continuous with liver and splenic capsules encapsulated all abdominal organs. Microscopically the abdominal wall and fibrous capsule consisted of an irregular thick layer of hypocellular connective tissue. The final diagnosis was sclerosing encapsulating peritonitis.     

IMAGING DIAGNOSIS—METASTATIC ADRENAL PHEOCHROMOCYTOMA IN A DOG

A 10‐year‐old Akita mix became acutely paraplegic. Upon magnetic resonance imaging, multiple, slightly T2‐hyperintense, T1‐isointense extradural masses, relative to spinal cord were found in the vertebral canal. The retroperitoneal masses had mixed T2‐signal intensity. The contrast enhancement pattern for the spinal masses was both homogenous and heterogenous. The diagnosis was metastatic pheochromocytoma. Signal intensity of the tumors in this dog was similar to reports of pheochromocytoma in human beings.     

IMAGING DIAGNOSIS—PULMONARY ALVEOLAR PROTEINOSIS IN A DOG

A young dog was presented for cyanosis and right heart failure. Radiographic and CT characteristics included right heart/pulmonary artery enlargement, hepatomegaly, abdominal effusion, and severe, generalized air‐space filling. Focal increased opacities were present in the peripheral lung, as were multiple pulmonary blebs and bullae. Echocardiographic findings were consistent with cor pulmonale and pulmonary hypertension. Bronchoscopic findings were consistent with chronic inflammation. Pulmonary alveolar proteinosis (PAP) was confirmed at necropsy. Pulmonary alveolar proteinosis is an interstitial lung disease that results in accumulation of phospholipoproteinaceous material and should be included as a differential diagnosis for dogs with these clinical and imaging characteristics.     

IMAGING DIAGNOSIS—CANINE MENINGIOANGIOMATOSIS

Meningioangiomatosis is a rare proliferative disorder of the central nervous system. It occurs sporadically in dogs and is characterized by a leptomeningeal plaque that extends from the subarachnoid space along the perivascular spaces into the adjacent parenchyma. We describe the clinical presentation, magnetic resonance (MR) imaging and neuropathologic characteristics of two additional dogs with meningioangiomatosis, and document involvement of the thoracolumbar spinal cord, a site not previously described for this condition. MR imaging findings were different from those previously described, most likely reflecting the degree of vascularity and collagen deposition. The MR imaging features of meningioangiomatosis are not specific.