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—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—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—COMPUTED TOMOGRAPHIC,SURGICAL, AND HISTOPATHOLOGIC CHARACTERISTICS OF AN INFILTRATIVE ANGIOLIPOMA IN A DOG

A 6‐year‐old female spayed Shetland Sheepdog presented for evaluation of a subcutaneous mass over the right prescapular region. The mass had been cytologically diagnosed as a lipoma by the referring veterinarian 20 months prior, but had grown significantly and was very firm. CT scan of the mass was suggestive of neoplasia; however, the tissue of origin could not be determined. Histopathologic evaluation diagnosed infiltrative angiolipoma, and marginal resection of the tumor was performed. Infiltrative angiolipomas are benign but locally aggressive neoplasms uncommonly reported in veterinary medicine. This report correlates the clinical, CT, and histopathologic characteristics of an infiltrative angiolipoma.     

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—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—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—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—SPINAL EPIDURAL HEMANGIOSARCOMA IN A DOG

An 8‐year‐old, male Boxer was examined for an acute onset of ambulatory paraparesis. Neurologic examination was consistent with a T3‐L3 myelopathy. Myelography revealed an extradural spinal cord compression in the region of the T10‐T13 vertebrae. On magnetic resonance (MR) imaging, a well‐defined epidural mass lesion was detected. The mass was mildly hyperintense on T1‐weighted, hyperintense on T2‐weighted and STIR images compared to normal spinal cord and enhanced strongly and homogenously. Postmortem examination confirmed a primary epidural hemangiosarcoma. Findings indicated that the MRI characteristics of spinal epidural hemangiosarcoma may mimic other lesions including meningioma and epidural hemorrhages/hematomas of non‐neoplastic etiology.     

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—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—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.     

SCINTIGRAPHIC DETECTION OF SUBCUTANEOUS METASTASIS IN A DOG WITH APPENDICULAR OSTEOSARCOMA

This report describes the detection of subclinical soft tissue metastasis of an appendicular osteosarcoma in a dog using bone scintigraphy. A 7-year-old spayed female Rottweiler was presented with a biopsy confirmed diagnosis of osteosarcoma. Initial radiographs revealed an aggressive bone lesion of the left distal radius. At presentation, there was no clinical or radiographic evidence of metastasis; however, a nuclear bone scan showed the primary bone lesion of the distal left radius and numerous soft tissue lesions consistent with diffuse soft tissue metastases. A left foreleg amputation was performed and cisplatin chemotherapy was given post-operatively. A second bone scan performed one month following initial presentation showed progression in size and number of soft tissue masses. Many of the lesions had become apparent on physical exam and survey radiographs. Excisional biopsy was performed on one of the soft tissue masses and a diagnosis of metastatic osteosarcoma was made. The dog was euthanized 2 months after initial presentation at the owners request due to deterioration of the animals physical condition.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY FINDINGS IN A CASE OF METASTATIC OVARIAN ADENOCARCINOMA IN A DOG

A 5‐year‐old female entire German Shepherd presented for otitis and lethargy. An incidental abdominal mass was identified on examination. Ultrasound examination (US) identified a heterogeneous left ovarian mass. Computed tomography (CT) was performed for surgical planning and staging. The reproductive tract was removed en bloc and submitted for histopathology. Multiple small (1–5 mm) nodules identified at coeliotomy on the surface of the liver, spleen and peritoneum were biopsied. The lesions were not visible on CT nor US on review. This is the first case report of the CT findings of ovarian papillary adenocarcinoma with carcinomatosis.     

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—DISCOSPONDYLITIS AND SEPTIC ARTHRITIS IN A DOG

A 6-year-old German Shepherd dog was evaluated for hind limb lameness. When a diagnosis, could not be achieved using radiography and ultrasonography, bone scintigraphy was performed to look for occult lameness or the presence of multiostic disease. Bone scintigraphy was useful in identification of increased radiopharmaceutical uptake in the thoracic spine and right coxofemoral joint, which directed further testing leading to the diagnosis of discospondylitis, septic arthritis of the coxofemoral joint, and a urinary tract infection.     

IMAGING DIAGNOSIS—IMAGING AND HISTOPATHOLOGIC CHARACTERISTICS OF A VERTEBRAL HAMARTOMA IN A CAT

A 9‐month‐old domestic shorthair cat had progressive ambulatory paraparesis, proprioceptive ataxia, and thoracolumbar hyperesthesia. An extradural mass affecting the left pedicle and lamina of the second lumbar vertebra (L2) causing marked spinal cord impingement was identified in magnetic resonance (MR) images. The mass was predominantly calcified in computed tomographic (CT) images. A hemilaminectomy was performed to resect the mass. Clinical signs were greatly improved at 12‐month follow‐up. The histopathologic diagnosis was vascular hamartoma. To our knowledge, this is the first report describing the MR characteristics of a vascular hamartoma associated with the vertebral column.     

IMAGING DIAGNOSIS—MALIGNANT PERIPHERAL NERVE SHEATH TUMOR PRESENTING AS AN INTRA‐AXIAL BRAIN MASS IN A YOUNG DOG

A 3‐year‐old Labrador retriever was presented with acute onset seizures. Magnetic resonance imaging demonstrated an intra‐axial mass affecting the right temporal lobe of the brain. Surgical resection and histopathological findings were most consistent with a malignant peripheral nerve sheath tumor. After initial recovery, deterioration 3 months post surgery prompted euthanasia. Post‐mortem revealed a mass protruding from the ventral surface of the temporal lobe, encroaching upon the optic chiasm and invading the brain. Histopathology findings were again consistent with malignant peripheral nerve sheath tumor. Although rare, this tumor should be included as a possible differential diagnosis for intra‐axial brain masses in dogs.     

IMAGING DIAGNOSIS—TRANSESOPHAGEAL ULTRASOUND‐GUIDED REMOVAL OF A MIGRATING GRASS AWN FOREIGN BODY IN A DOG

A 3‐year‐old English Setter dog was presented for an acute onset of coughing. Tracheobronchoscopic examination allowed localization and removal of one grass awn foreign body. A second migrated grass awn was suspected to be present in the left caudal lung lobe. Transesophageal ultrasound revealed an area of pulmonary consolidation in the dorsomedial portion of left caudal lobe and a linear hyperechoic structure consistent with a grass awn foreign body within the area of consolidation. Transesophageal ultrasonography was also used to provide anatomical landmarks that facilitated successful thoracoscopic removal of the foreign body.