Veterinary Clinical Pathology ISSN 0275-6382
Cholesteatoma and meningoencephalitis in a dog with chronic otitis externa Ashleigh W. Newman1, Chelsie M. Estey2, Sean McDonough3, Sofia Cerda-Gonzalez2, Meegan Larsen3, Tracy Stokol1 Departments of 1Population Medicine and Diagnostic Sciences, 2Clinical Sciences, and 3Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
Key Words Cerebrospinal fluid analysis, cytology, epidermoid cyst, keratinized squamous epithelial cells Correspondence A. Newman, S1 056 Schurman Hall, 602 Tower Road, Cornell University College of Veterinary Medicine, Ithaca, NY 14853, USA E-mail: [email protected]
Abstract: A 10-year-old female spayed German Shepherd dog, with a year-long history of recurrent left ear infections, was presented for progressive ataxia, head tilt, and pain on opening of the mouth. On physical examination, a large amount of ceruminous debris was present in the left ear and multiple neurologic defects localizing to the cerebellum and vestibular system were identified. Magnetic resonance imaging (MRI) demonstrated a minimally contrast-enhancing mass within the left bulla, an intracranial space-occupying, heterogeneously contrast-enhancing lesion at the level of the left cerebello-medullary junction, and contrast enhancement of the ipsilateral meninges. Cerebrospinal fluid analysis revealed a marked mixed cell pleocytosis (nucleated cell count 655 cells/lL). The mass was visualized within the horizontal ear canal by otoscopic examination and a biopsy was taken. Impression smears of the biopsy contained many anucleate keratinized squamous epithelial cells, mild mixed inflammation, and few presumptive fibroblasts. With the provided clinical history and MRI findings, a cytologic diagnosis of cholesteatoma was made. A ventral bulla osteotomy was performed, and histopathologic examination of resected tissue confirmed the cytologic diagnosis of cholesteatoma. The dog’s clinical symptoms improved postoperatively, but the dog died of unrelated causes, 3.5 months later. To our knowledge, this is the first description of the cytologic features of a cholesteatoma, which is a nonneoplastic, but locally invasive epidermoid cyst, in the middle ear of dogs.
Case Presentation A 10-year-old female spayed German Shepherd dog was presented to the neurology service at the Cornell University Hospital for Animals (CUHA) for evaluation of progressive neurologic signs in the previous 3 months. The dog had suffered from recurrent infections in the left ear for one year, which were managed by the referring veterinarian with numerous antibiotics and corticosteroids. Three months before presentation to CUHA, the owner had noted reduced barking and pain when the mouth was opened. These clinical signs responded partially to amoxicillin therapy. The dog then developed neurogenic keratoconjunctivitis sicca (KCS) of the left eye, followed by a left head tilt, disorientation, and difficulty walking and navigating stairs.
The dog had a more recent onset of decreased appetite and anxious behavior. On physical examination at CUHA, the dog was bright, alert, and responsive with normal vital signs and a body condition score of 4/9. There was mild thickening of the pinna and a copious amount of ceruminous debris in the left ear. Pain was elicited upon palpation of the temporomandibular joint. Neurologic examination revealed multifocal neurologic deficits including a left head tilt, left ear and lip droop, left body lean at rest, vestibular ataxia, forelimb hypermetria, left positional ventral strabismus, an absent menace response in the right eye, and delayed proprioception in the right front and hind limbs. All of the dog’s neurologic signs localized to a right-sided cerebello-medullary angle lesion including cerebellar, paradoxical vestibular due to cerebellar peduncle involvement,
Vet Clin Pathol 44/1 (2015) 157–163 ©2014 American Society for Veterinary Clinical Pathology
Cholesteatoma in a dog with chronic otitis externa
Newman et al
and right medullary involvement for the proprioceptive deficits. A mucoid ocular discharge in the left eye, consistent with the previously documented neurogenic KCS, and a dry, crusted left nostril were attributed to loss of autonomic fibers traveling with the facial nerve. The facial paresis, as manifested by the left ear and lip droop, could have been a chronic finding referable to the previous infections in the left ear. Results of a CBC (ADVIA 2120; Siemens Healthcare Diagnostics Inc, Tarrytown, NJ, USA with manual blood smear examination) revealed an inflammatory leukogram characterized by a moderate leukocytosis (23.3 9 103/lL; reference interval [RI] 5.7– 14.3 9 103/lL) consisting of a mature neutrophilia (18.6 9 103/lL; RI 2.7–9.4 9 103/lL) and monocytosis (3.3 9 103/lL; RI 0.1–1.3 9 103/lL) with a concurrent inflammatory or stress-induced eosinopenia (0 9 103/lL; RI 0.1–2.1 9 103/lL). The HCT and platelet count were within RI, and no abnormalities were noted on blood smear examination. A biochemical profile and thyroid testing panel showed no abnormalities. Thoracic radiographs were unremarkable. Magnetic resonance imaging (MRI) revealed a large (approximately 3.0 9 2.0 9 1.5 cm), irregularly shaped, minimally contrast-enhancing mass within the left bulla, with lysis of the overlying petrous temporal bone (Figure 1A, asterisk). There was an associated intracranial space-occupying, heterogeneously contrast-enhancing lesion at the level of the left cerebello-medullary junction (Figure 1A, arrow). Contrast enhancement also extended from the lesion, tracking along the meninges (Figure 1A, arrowhead). Contrast enhancement of the intracranial lesion, ipsilateral perilesional meninges, soft tissues of the middle and external ear, and soft tissues surrounding the temporomandibular joint was observed after gadolinium administration, supporting a concurrent inflammatory process. However, there appeared to be some continuity between the mass in the bulla and the intracranial lesion, suggesting possible invasion of the bulla mass through the lytic petrous temporal bone into the cranial cavity (Figure 1B, arrow). Analysis of cerebrospinal fluid (CSF) collected from the cerebello-medullary cistern revealed a marked mixed cell pleocytosis (655 cells/lL, reported RI, 0–3 cells/lL1) consisting of 71% nondegenerate neutrophils, 22% macrophages, and 7% lymphocytes, including reactive forms, with an increased total protein (165 mg/dL, reported RI,