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Keywords:

  • Falco peregrinus cassini ;
  • neoplasia;
  • neotropical;
  • raptors;
  • rhabdomyosarcoma

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case Report
  5. Discussion
  6. References

A mild swelling of the left periorbital was detected on a routine physical exam of a healthy captive adult peregrine falcon. Despite treatment, the swelling did not subside and within twenty-five days was causing significant exophthalmia and medial deviation of the left globe. A retrobulbar fusiform cell sarcoma was diagnosed with histopathology, then light microscopy and immunohistochemical staining confirmed the diagnosis of a rhabdomyosarcoma.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case Report
  5. Discussion
  6. References

In 2009, the Peruvian National Institute of Natural Resources (INRENA Instituto Nacional de Recursos Naturales) confiscated a wild-caught, healthy juvenile female peregrine falcon and placed the falcon into long-term care at El Huayco, a private raptor reproduction and rehabilitation center. El Huayco is the largest neotropical raptor breeding center in South America and receives many sick, injured, or confiscated birds. After a quarantine period, the falcon was housed in a separate pen 30 m3 and fed freshly killed, then frozen, quail, similar to the other 56 peregrine falcons at El Huayco. At breeding age, the falcon was integrated into the breeding program, placed in a larger aviary with a mate and successfully bred in 2009. There were no previous health issues.

Case Report

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case Report
  5. Discussion
  6. References

On 21/2/11, a mild swelling was noticed around the left eye of one of the Peregrine falcons during the daily check of the aviaries. On physical examination, the bird presented with a diffuse conjunctiva congestion and swelling of the left periocular tissue. Intraocular pressure and Ultrasound (15 Megahertz) examinations of both eyes were within normal reference ranges. An ophthalmic examination revealed conjunctival congestion and chemosis. No discharges or traumas were detected. There were no other significant findings. It was suspected the swelling was caused by an insect bite or a mild topical irritant. The left eye was flushed with sterile saline and treated with ophthalmic ciprofloxacin (Ciprovet®, LABYES®, Dexer S.R.L. Surquillo, Lima, Peru) at 1 drop twice a day for 6 days. The periocular swelling and congestion did not decrease with treatment. Sterile swabs were used to sample the lower conjunctiva of both eyes. Culture results revealed Citrobacter sp. and Staphylococcus aureus from both eyes, and Aspergillus flavus in the left. We consider these fungi to be contaminants from the soil that was disturbed during capture.

The periocular mass had increased significantly in size, was multilobulated and firm (Fig. 1), and was causing increased corneal opacity and conjunctival inflammation. Due to the lack of treatment response, and progressive nature of the mass, the falcon was humanely euthanized by injection. A necropsy was performed (Fig. 2). The mass, brain, and both eyes were placed in 10% buffered formalin and submitted for histopathology and histochemistry.

image

Figure 1. Left eye of the peregrine showing a multi bulbous mass and corneal opacity.

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image

Figure 2. During necropsy, comparing the normal OD with exophthalmia, the retrobulbar mass and opacity of the OS.

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The histopathological investigation revealed that the left periocular mass, showed fusiform cells consistent with a retrobulbar neoplasm (Fig. 3). There was inflammation with mild infiltration of the interstitial spaces with mononuclear degeneration (Zenker necrosis) of the left striated ocular muscle. A large focal infiltration of fusiform neoplastic cells into the sclera of the left globe was detected. There were no significant findings in the right eye. There was encephalomalacia with vacuolization and splitting and cracking, in addition to mobilization of the glia, satelitosis, and neuronophagia of the cerebrum. Hyaline thrombi were evident in the capillaries.

image

Figure 3. An H.E. stain photomicrograph at 400× of the retrobulbar mass revealing striated muscle cells with sarcoma tumour cells lining the alveolar.

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The mass was histopathologically identified as a retrobulbar fusiform cell sarcoma originating from the striated muscle. To differentiate the retrobulbar fusiform cell sarcoma, the mass was subjected to immunohistochemical staining. The results of the staining were negative for Desmin D33, and focally immunopositive for Actin 1A4 and these immunohistochemical staining patterns confirm the diagnosis of rhabdomyosarcoma.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case Report
  5. Discussion
  6. References

There are a number of reports of retrobulbar neoplasms normally associated with exophthalmos in birds, in general, that include: lymphomas, adenomas, adenocarcinomas, medulloepitheliomas, rhabdomyosarcomas, undifferentiated carcinoma, tetroma, and a glioma.[1] Twelve different neoplasms have been documented from different locations of the body in the boreal peregrine falcon while none have been reported in the retrobulbar region.[2] To our knowledge, there are no reports of neoplasia in the austral peregrine falcon (Falcon peregrinus cassini).

Neoplasms of the retrobulbar region are usually differentiated by tissue origin and immunohistochemical staining,[3] which is now the preferred method for differentiation and diagnosis of sarcomas and rhabdomyosarcomas.[4, 5] Immunopositive reactions to desmin are normally deterministic in the diagnosis of rhabdomyosarcomas;[6, 7] however, we had a negative reaction to desmin and a positive reaction to actin. This may indicate a poorly differentiated rhabdomyosarcoma and could be evaluated further using myoglobin which was not available.[6] As rhabdomyosarcomas are derived from skeletal or striated muscle cells[5] and based upon our histopathological and immunohistochemical results, we believe that this sarcoma is a poorly differentiated rhabdomyosarcoma.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case Report
  5. Discussion
  6. References
  • 1
    Latimer KS. Oncology. In: Avian Medicine: Principles and Applications. (eds Ritchie BW, Harrison GJ). Winger's, Lake Worth, 1994; 640672.
  • 2
    Forbes NA, Cooper JE, Higgins JH. Neoplasms of Birds of Prey. In: Raptor Biomedicine III including Bibliography of Diseases of Birds of Prey. Lumeij JTDR. (eds Redig P, Lierz M, Cooper JE) Zoological Education Network Inc, Lake Worth, Florida, 2000; 127145.
  • 3
    Manarolla G, Radaelli E, Pisoni G et al. Rhabdomyosarcoma of the pectoral muscles of a free-living European robin (Erithacus rubecula). Avian Pathology 2008; 37: 311314.
  • 4
    Maluenda AC, Casagrande RA, Kanamura CT et al. Rhabdomyosarcoma in a yellow headed Caracara (Milvago chimachima). Avian Diseases 2010; 54: 951954.
  • 5
    Cooper BJ, Valentine BA. Tumours of Muscle. In Tumors in Domestic Animals. 4th edn. Iowa State Press, Iowa, 2002; 319363.
  • 6
    Fernandez-bellon H, Martorell J, Rabanal R, Ramis A. Rhabdomyoszarcoma in a racing pigeon (Columba livia). Avian Pathology 2003; 32: 6.
  • 7
    Skalli O, Gabbiani G, Babai F, Seemayer TA, Schurch W. Intermediate filament proteins and actin isoforms as markers for soft tissue tumor differentiation and origin. American Journal of Pathology 1988; 130: 515531.