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Bilateral aural adenocarcinoma in a Congo African grey parrot (Psittacus erithacus erithacus).

Abstract: A 28-year-old female Congo African grey parrot (Psittacus erithacus erithacus) was evaluated because of a mass in the left external auditory meatus. Results of a computed tomography scan revealed an osteolytic left hemimandibular mass with irregular bone production and a soft tissue mass in the left external auditory meatus. Results of cytologic examination of fine needle aspirates of the hemimandible were interpreted as adenocarcinoma with reactive osteoblasts. The owner chose palliative treatment, and a debulking procedure was performed on the left external auditory meatus mass 52 days after initial presentation to control self-trauma. Euthanasia was elected 67 days after initial presentation because of poor prognosis associated with the development of bilateral masses of the external auditory meatus and lateral deviation of the mandible, findings that were confirmed by postmortem examination. Histopathologic results confirmed the diagnosis of bilateral aural adenocarcinoma with invasion of both temporal bones and hemimandibles.

Key words: adenocarcinoma, neoplasia, external auditory meatus, bird, avian, African grey parrot, Psittacus erithacus erithacus

Clinical Report

A 28-year-old female Congo African grey parrot (Psittacus erithacus erithacus) was presented to the Veterinary Medical Teaching Hospital (VMTH) at the University of California, Davis, for scratching the left side of its face, a mass in the left external auditory meatus, and cessation of vocalization. The referring veterinarian had performed a biopsy from the external auditory meatus mass 15 days before presentation. Biopsy results were suggestive of an infiltrative adnexal adenocarcinoma but were unavailable for pathologic review at the VMTH.

On presentation, the bird, weighing 348 g, had a mildly thin body condition (4/9), bilateral incipient cataracts, a tan-to-yellow soft mass visible within but not protruding from the left external auditory meatus, and dried blood on the feathers surrounding the meatus. No masses were visible in the right external auditory meatus. Radiographs and blood tests were declined by the client. Meloxicam (1 mg/ kg PO q12h) was prescribed for its anti-inflammatory and potential antiangiogenic properties. (1)

A computed tomography (CT) scan was performed with the bird under general anesthesia. The anesthetic protocol consisted of premedication with midazolam (1.4 mg/kg IM) and butorphanol (1 mg/kg IM, Torbugesic, Fort Dodge Animal Health, Fort Dodge, I A, USA), anesthetic induction with isoflurane (2%) in 1 L CU/min by mask, and anesthetic maintenance with 1.5% isoflurane in 1 L [O.sub.2] /min via a 2.5-mm uncuffed endotracheal tube. The CT scan utilized GE Lightspeed 16 (General Electric Healthcare, Little Chalfont, UK) with 0.6-mm transverse slices through the skull and body (bone and soft-tissue algorithms precontrast and soft tissue algorithm post-contrast). Contrast was enhanced with iopamidol (0.65 mg/ kg IV, Isovue 370, Bracco Diagnostics Inc, Princeton. NJ. USA) via a 24-gauge catheter in the right basilic vein. The left hemimandibular body was affected by severe, moth-eaten osteolysis and was also mildly expansile with irregular new bone production. Soft, tissue-dense, non-contrast-enhancing material filled the left external auditory meatus and tympanic cavity. The temporal bone was thin with irregularly margined destruction at the dorsomedial aspect of the left tympanic cavity. No significant regional soft tissue swelling, contrast enhancement, or invasion of the brain case was identified (Fig 1). The imaging characteristics were interpreted as an aggressive polyostotic disease process, most likely neoplasia, although osteomyelitis was considered a less likely differential. Two fine needle aspirates of the body of the left hemimandible were collected by a 3-mL syringe and 25-gauge needle while the bird was under general anesthesia. After the procedure, the midazolam was reversed with fiumazenil (0.05 mg/kg intranasal), and the bird recovered uneventfully.

Cytologic samples, stained with Wright-Giemsa, were highly cellular with a densely bloody background containing frequently disrupted nucleated cells. Cells were polygonal with a medium volume of blue-grey cytoplasm, had occasional clear, punctate vacuoles, and were distributed in variably sized cohesive sheets with palisading nuclei that occasionally formed acinarlike arrangements. Nuclei were round with stippled chromatin and prominent nucleoli. Anisocytosis and anisokaryosis were moderate with high nuclear-to-cytoplasm ratios. Lesser numbers of osteoblasts were scattered across the samples (Fig 2). Findings were interpreted as an adenocarcinoma with reactive osteoblasts, which may represent metastatic disease or extension of a primary mass into adjacent bone. Surgical and radiation therapies were declined by the client. Monitoring the bird's quality of life and continuing meloxicam therapy were recommended. The bird returned to normal vocalization and appetite after initiating the meloxicam regimen.

The bird, weighing 365 g, was presented a second time to the VMTH 52 days after initial presentation. One week before, the bird had begun scratching at the left external auditory meatus once again. On examination, a left external auditory meatus mass protruded 3 mm from the skin surface, was red, and had small amounts of dried blood on the surrounding skin. The right external auditory meatus was clean with no masses visible. Because of concern for continued self-trauma, a debulking procedure was performed. Under sedation with midazolam (1 mg/kg IM) and butorphanol (1 mg/kg IM), a combination of sharp and blunt dissection was used to debulk the mass to a concave shape that did not protrude from the external auditory meatus. A moderate amount of bleeding was controlled with digital pressure and cauterization with a high-temperature cautery. Trimethoprim-sulfamethoxazole (30 mg/kg PO q12h) was prescribed for 5 days for potential secondary infection, in addition to continuing treatment with meloxicam.

The bird presented 67 days after initial presentation because of a quieter disposition, acute development of a beak malocclusion, and decreased appetite. On physical examination, mandibular drift, a palpable defect in the left hemimandible, and tan-colored masses protruding from both external auditory meatuses were observed. The client elected euthanasia because of the severity of the lesions, and the body was submitted for postmortem examination.

At postmortem examination a dark-red to brown, 0.5 x 0.5-cm, irregularly shaped, exophytic mass was identified in the left external auditory meatus (Fig 3A), and the right external auditory meatus contained a light-brown, smooth mass measuring 0.2 x 0.3 cm (Fig 3B). The gnathotheca was deviated 0.2 cm laterally to the left in relation to the rhinotheca, and the left hemimandible was variably pliable. No visceral lesions were observed.

Results of histopathologic examination confirmed the aural masses were neoplasms that consisted of islands and cords of neoplastic epithelial cells embedded within abundant connective tissue, further admixed with immature blood vessels, necrotic debris, and keratin-like fragments surrounded by numerous multinucleated giant cells. Many heterophils infiltrated the mass from the left side. Squamous epithelium overlying the connective tissue was variably dysplastic, with some foci of epithelial cells breaching the basement membrane. Neoplastic epithelium was extensive within the medullary cavities of both temporal bones and hemimandibles. Direct communication between the aural and intramedullary neoplasms was evident on the right side, although neoplastic cells extended through cortical bone in the vicinity of the left external auditory meatus.

Within the medullary spaces, the neoplasm consisted of sheets, cords, and islands of densely packed, polyhedral neoplastic cells that were variably supported by abundant immature desmoplastic fibrous connective tissue. Neoplastic cells adjacent to the right external auditory meatus delineated a potential space, and at 1 small focus, the malignant cells formed a simple columnar epithelium with basal nuclei. In many areas, variably sized cystic spaces within the tumor demarcated negatively stained material, eosinophilic fluid, or occasionally necrotic debris. Larger foci of coagulative necrosis were also present but uncommon. Neoplastic cells were variably sized and poorly differentiated, with moderate amounts of lightly vesicular cytoplasm and indistinct cell margins. Nuclei varied widely in size and shape, and mitotic figures were common in some regions. Many osteoclasts were present in deep resorption lacunae in the vicinity of the invasive neoplastic cells and where the neoplasm directly abutted bone. The left hemimandible was largely obliterated by the neoplasm and cords of neoplastic cells extending into the surrounding periosteal connective tissue (Fig 4). Regions of the medullary cavity adjacent to neoplastic foci often contained abundant cell debris, immature fibrous connective tissue, and numerous epithelioid macrophages, many of which had vesicular cytoplasm. Acicular clefts were numerous in some foci. The final diagnosis was bilateral aural adenocarcinoma with invasion of both temporal bones and hemimandibles. Renal tubular adenoma and type V atherosclerosis were also observed but were considered incidental findings. No microscopic lesions were identified in samples of cerebrum, liver, intestine, thyroid, spleen, ventriculus, pancreas, or proventriculus.


This report documents an adenocarcinoma within the external auditory meatus in a 28-yearold female Congo African grey parrot with invasion of the temporal bones, the contralateral external auditory meatus, and both hemimandibles. At postmortem examination, the origin of the glandular tumor was not determined. Few true cutaneous glands are found in birds, principally the uropygial gland, glands around the vent, and secretory glands of the external auditory meatus. (2) Possible origins of adenocarcinomas of the external auditory meatus in people include ceruminous or sebaceous glands, direct invasion from the parotid gland, or distant metastasis from other glandular tissues. (3) Based upon the absence of other foci of malignant glandular neoplasia, this bird's neoplasia most likely originated from the glands of the external auditory meatus. The histologic features of the glands of the avian external auditory meatus have been reported; however, information is limited about whether glands are ceruminous or sebaceous in nature. (4-6)

Aural sebaceous adenocarcinomas have been reported in people, dogs, a cat, and a rabbit. (7-10) In people, ear meatus tumors occur at an incidence of 1 in 1,000,000 individuals, with less than 18% of those of glandular origin." The prevalence in veterinary species ranges from 1% to 2% of all tumors in cats to 2% to 6% of dogs presented for aural surgery .(8) Only one other case of a malignant aural adenocarcinoma has been reported in avian species, in a common goose (Anser anser domesticus). (12) Based on the scarcity of reports of this tumor type, it is likely a rare occurrence in birds.

Chronic inflammation has been suggested as a risk factor for the development of benign and malignant tumors of the ear meatus in both people and dogs. Chronic otitis externa persisting for more than 6 months is a common history associated with malignant tumors of the ear meatus in dogs. (8) The bird in this report had no such previous history of ear pathology. In people, risk factors for neoplasia of the ear meatus also include advanced age, Asian or South Asian race, female sex, previous irradiation to the head and neck, and some genetic disorders. (7)

Clinical signs of ear meatus tumors in dogs are otic discharge, odor, pruritus, signs of pain, and the presence of a mass. Facial nerve paresis and vestibular disease were associated with poor prognosis in cats, (8) whereas pain and facial nerve palsy are indicators of malignancy in people. (13) In this report, clinical signs and physical examination findings included scratching at the aural meatus and the presence of a mass. We assumed that the bird exhibited pain based on its favorable response to anti-inflammatory administration. Lack of interaction and decreased vocalization are manifestations of pain in social avian species such as parrots. (14) The bird's pain may have been caused by the close proximity of the mass to nervous structures or the destruction and invasion of tissues. The acute finding of mandibular drift noted on final examination was likely secondary to the severe lysis of the bone and subsequent pathologic fracture of the left hemimandible. This invasion was more extensive and severe than that noted in the report of bilateral aural adenocarcinoma in a common goose. (12)

In cats, tumors of the ear meatus are often diagnosed by fine needle aspirate. (15) CT or magnetic resonance imaging are preferred over radiographs to rule out destruction and invasion of adjacent soft tissues. In this report, the CT scan aided in evaluation of the tumor's effect on the bony structures and prognosis development. The right external auditory meatus involvement observed at postmortem examination were not detected by the CT scan, which may be attributed to the spatial resolution limitations of the CT scanner or absence of disease in those structures at the time of the CT scan. A CT scan did identify bilateral aural masses in the report of the common goose. (12)

Surgery is a common treatment for ear meatus tumors. In cats, total ear meatus ablation is the preferred surgical option for ceruminous gland adenocarcinomas, resulting in a longer disease-free interval and lower recurrence rate." (16) Radiotherapy may be used as an adjuvant to treatment in dogs, cats, and people, especially if the tumor is not fully resected. (7-8) After consultation with surgeons and oncologists, treatment in this case would have required bilateral hemimandibulectomy, radiation therapy, or both.

The extensive local invasion seen in this case report is a common finding of ear meatus neoplasia in other species. Malignant ear meatus neoplasia of dogs and cats infrequently metastasize yet have a propensity for local invasion. (8) In this case, invasion of the temporal bones, hemimandibles, and contralateral external auditory meatus was present. The route of extension of the neoplasm into the hemimandible from the temporal bone or the external auditory meatus was only evident in the histologic sections examined from the right hemimandible. This route was assumed to be present on the left but was out of the plane of the examined histologic sections.

This clinical report details the presentation of an advanced case of aural adenocarcinoma in a Congo African grey parrot, including clinical findings, short-term palliative treatment, and progression of the disease. Early detection of external auditory meatus neoplasia paired with aggressive surgical intervention and radiation therapy are recommended to maximize the possibilities of a positive clinical outcome in cases of aural adenocarcinoma in birds.


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Emma L. Houck, DVM, Krista A. Keller, DVM, Dipl ACZM, Michelle G. Hawkins, VMD, Dipl ABVP (Avian), Andrew G. Burton, BVSc, Dipl ACVP, Keriann M. Casey, DVM, Kevin Keel, DVM, PhD, Dipl ACVP, Nathan Tong, DVM, MBA, Dipl ACVR, and David Sanchez-Migallon Guzman, MS, LV, Dipl ECZM (Avian, Small Mammal), Dipl ACZM

From the William R. Pritchard Veterinary Medical Teaching Hospital (Houck, Keller, Burton, Casey, Tong) and the Department of Medicine and Epidemiology (Hawkins, Keel, Guzman), School of Veterinary Medicine, 1 Shields Avenue, University of California at Davis, Davis, CA 95616, USA. Present addresses: Thrive Veterinary Care, 4175 East Warren Avenue, Denver, CO 80222, USA (Keller); Antech Diagnostics, 1111 Marcus Avenue, Lake Success, NY 11042, USA (Burton).
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Article Details
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Author:Houck, Emma L.; Keller, Krista A.; Hawkins, Michelle G.; Burton, Andrew G.; Casey, Keriann M.; Keel,
Publication:Journal of Avian Medicine and Surgery
Article Type:Clinical report
Date:Sep 1, 2016
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