Leiomyosarcoma of the Wing in a Vieilott's fireback pheasant (Lophura rufa).
Key words: leiomyosarcoma, smooth muscle neoplasm, immunohistochemistry, avian, Vieilott's fireback pheasant, Lophura rufa
A 15-year-old, female Vieilott's fireback pheasant (Lophura rufa) weighing 1.4 kg, with thin body condition, was presented to the Fort Worth Zoo's Veterinary Hospital (Fort Worth, TX, USA) because of a drooping right wing. On examination, marked soft tissue swelling extended from the right shoulder to the humeral-radio-ulnar joint with associated feather loss. An open, minimally painful wound, with marked soft tissue swelling and green discoloration, was observed in the right elbow (Fig 1A). When compared with the contralateral wing, the circumference of the affected wing was double in size. The bird showed minimal pain reaction during manipulation of the affected wing. Results of a complete blood cell count revealed absolute leukocytosis (67 500 cells/[micro]L; reference interval [mean [+ or -] SD], 22 600 [+ or -] 11 120 cells/[micro]L) characterized by marked heterophilia (39 825 cells/[micro]L; reference interval, 9892 [+ or -]4813 cells/[micro]L), and mild lymphocytosis (27 675 cells/[micro]L; reference interval, 9755 [+ or -] 8352 cells/[micro]L), which corresponded to the severe tissue inflammation of the right wing. (1) Results of serum biochemical analysis showed a severe increase in creatine kinase activity (67 265 U/L; reference interval, 2156 [+ or -] 801 U/L), moderate increase in aspartate aminotransferase activity (633 U/L; reference interval, 304 [+ or -] 94 U/L), and mild hypoproteinemia, characterized by decreased values for albumin (1.0 mg/dL; reference interval, 2.0 [+ or -] 0.4 mg/dL), total protein (3.2 mg/dL; reference interval, 4.6 [+ or -] 0.5 mg/dL), and globulins (2.2 mg/dL; reference interval, 2.9 [+ or -] 0.4 mg/dL). (1)
Ventrodorsal (Fig 1B) and right lateral orthogonal radiographs revealed that the right humerus was diffusely mottled in opacity with loss of healthy bone trabeculation. Poorly defined regions of lysis were identified within the proximal and distal right humeral metaphyses. These lytic lesions extended proximally and distally to the margins of articular subchondral bone. An oblique, irregularly marginated fracture was identified through the proximal humeral metaphysis. On the ventrodorsal view, that fracture appeared to extend through the cranial cortex of the humerus at 2 sites, just distal to the subchondral bone of the humeral head, and to the level of the proximal diaphysis. The fracture was angulated with caudal rotation of the humeral head. A mild amount of sclerosis was identified along the fracture margins. The distal humerus was also fractured, with an oblique fracture line through the distal humeral epicondyle. That fracture appeared to extend distally to the subchondral bone and articular surface. A mild and diffuse, incompletely mineralized, smoothly marginated to palisading, periosteal bony proliferation was identified along the right humeral diaphysis. Moderate to marked soft tissue swelling of the right wing was identified, especially around the humerus. A small screw was also identified in the ventriculus. The main differential diagnoses included pathologic fractures because of neoplasia, osteomyelitis, or combinations thereof.
Given the severity of the lesion in the right wing, amputation was elected. Briefly, anesthesia was induced via face mask and maintained by delivery of sevoflurane (SevoFlo, Abbott Laboratories, Chicago, IL, USA) with a 2.5-mm Cole endotracheal tube. An incision was made in the right humeral-coracoid-scapular articulation; after surgical debridement of muscles, tendons, and connective tissue, the axillary artery and vein and nerves were ligated with 4-0 polydioxanone (PDS II, Ethicon, Somerville, NJ, USA). Samples of the mass incorporating humerus and brachial muscle were collected from the amputated wing and fixed in 10%-neutral formalin for histologic examination and immunohistochemistry. An additional tissue sample was obtained for aerobic and anaerobic bacterial culture and fungal culture. Muscular layers were closed with a horizontal mattress suture pattern (because of the high tension in the area) with 3-0 polydioxanone, and the skin was closed with same material in a simple, interrupted pattern. The bird received intravenous fluids, pain medications, and antibiotics during and after surgery and recovered well from anesthesia. Despite a successful amputation surgery, the bird appeared severely depressed the next morning and died while being treated.
Necropsy revealed a bird with the absence of subcutaneous and intracoelomic fat. The only gross abnormality was a 62-g pasty fecal mass filling the colon. Histologically, the wing lesion consisted of a neoplastic proliferation of spindle cells arranged in interlacing streams and bundles and short-stacking palisades of spindle cells that infiltrated the skeletal muscle (Fig 1C). These cells were spindloid with scant eosinophilic cytoplasm, elongated or ovoid nuclei with small nucleoli, mild anisokaryosis, variably blunt nuclear poles, and a mitotic index of 1 per 10 high-power fields. The tumor infiltrated skeletal muscle and humeral bone and was associated with bone lysis and reactive bone formation, hemorrhage, and necrosis. No infectious agents or lesions attributed to an infectious agent were seen histologically. To further determine the cell line of origin, immunohistochemical labeling for S100 protein (rabbit polyclonal anti-SlOO at 1:100, Novocastra, Newcastle, UK), CD34 (goat polyclonal anti-CD34 antibody at 1:80, Santa Cruz Biotechnology, Santa Cruz, CA, USA), smooth muscle actin (SMA; mouse monoclonal anti-SMA antibody at 1:100, Dako, Carpinteria, CA, USA), and vimentin (mouse monoclonal antivimentin antibody ViM3b4 at 1:50, Dako) was performed on 5-pm serial sections of the mass as follows: brain for S100 protein; uterus for SMA; haired skin for vimentin; and hemangiopericytoma for CD34. Smooth muscle cells of the blood vessels within the pheasant tissue showed cytoplasmic labeling for SMA, which was used as an internal positive control. The neoplastic cells showed labeling for vimentin and SMA and were negative for S100 protein (Fig ID). The fungus Scopulariopsis species was cultured from a sample of muscle tissue of the affected area, but no pathogenic bacteria were obtained. The fungal isolate was considered a contaminant. Histologic evidence of metastasis was not seen in the ventriculus, colon, intestines, ovaries, esophagus, lungs, liver, kidneys, great vessels, thyroid, thymus, large nerve, gallbladder, esophagus, trachea, or eyes. Additional histologic findings were moderate to marked atrophy of fat, mild mesangioproliferative glomerulopathy with renal tubular necrosis, and acute pulmonary congestion, hemorrhage, and interstitial pneumonia. The cause of death of this pheasant was attributed to a combination of pulmonary shock and low-grade sepsis. The source of the septic process was not apparent in the submitted tissues.
This report describes the clinical appearance, radiographic findings, and histopathologic features of a wing tumor in a Vieilott's fireback pheasant. Immunohistochemical labeling for vimentin and SMA allowed for further characterization of the tumor as a leiomyosarcoma.
Much data exist regarding the occurrence and prevalence of neoplasia in various avian species. In a recent review of a group of 22 avian orders studied, Galliformes, the order the Vieilott's fireback pheasant belongs to, ranked as the third order with the highest prevalence of neoplasia (9.9%). (2) Smooth muscle neoplasms are the most common muscle neoplasm reported in captive and free-ranging birds. (3,4) However, published cases of leiomyosarcoma in avian species are infrequent and describe budgerigars (Melopsittacus undulatus), (5,6) an Amazon parrot (Amazona aestiva), (7) a zebra finch (Taeniopygia guttata). (8) a domestic pigeon (Columba livia), (9) and Japanese quail (Coturnix japonica). (10) Furthermore, in most of the reported cases, this neoplasm affected only internal organs.
A histologic study of budgerigars reported 16 cases of leiomyosarcomas from 168 cases of neoplasia. The primary site affected was the spleen for 15 cases and intestine in 1 case; hepatic metastasis was observed in 2 of those cases. (5) Histologically, leiomyosarcomas are composed of sheets of spindle cells with eosinophilic cytoplasm and occasionally pleomorphic nuclei. (3)
There are only 2 previous reports of a leiomyosarcoma affecting a limb in an avian species. Specifically, one was in the subcutaneous tissue of the tarsometatarsus of a sarus crane (Grus antigone) where metastasis to the liver and kidneys occurred, (11) and the other was a subcutaneous leiomyosarcoma in the left humerus-radius-ulna joint of a Eurasian crane (Grus grus) that had metastasized to the lungs. (12) In our case, metastases were not observed, and the wing was considered the primary focus of the tumor.
In mammals, leiomyosarcomas are immunohistochemically positive for vimentin and SMA, and some are positive for desmin. (13) In birds, the specificity and sensitivity of the mammalian immunohistochemical markers can vary, and the presence of internal positive control tissues is helpful in assessing the usefulness of the markers. The neoplastic cells in this case exhibited moderate to strong cytoplasmic immunolabeling for vimentin and approximately 70% of the neoplastic cells showed strong cytoplasmic immunolabeling for SMA. An anti-SlOO protein was used to rule out a neoplasm of neural origin, such as a schwannoma or peripheral nerve sheath tumor. The neoplastic cells were negative for S100 protein. The CD34 is a marker that is used to detect neoplasms that originate in the perivascular wall, thus healthy vessels should be labeled with this marker as an internal control. None of the cells in the tissue sections labeled for CD34; consequently, that antibody did not appear to work in the formalin-fixed, paraffin-embedded tissues of this pheasant. There is a need to standardize immunohistochemical detection of these markers in most avian species, so their use can be available for a broader number of avian species, particularly endangered or rare ones.
Limited information exists on the treatment and survival of birds with leiomyosarcomas. Early and aggressive surgical excision is recommended to avoid recurrence, local invasion, and metastasis. (7,14) In the pheasant we describe, the gross appearance and size of the wing lesion suggested advanced neoplasia with the bird already in a compromised state, warranting a guarded prognosis.
Increases in creatine kinase and aspartate aminotransferase were attributed to the severe muscle insult and bone pathology; the hypoproteinemia and hypoalbuminemia were associated with the poor body condition. The foreign body identified in the ventriculus was considered an incidental finding. Scopulariopsis species fungus was deemed a contaminant because it is commonly found in soil and feathers, and there was no evidence of infection at the site of tumor development.
To our knowledge, this is the first report of the occurrence of a neoplasm in a fireback pheasant and the third report of a leiomyosarcoma described in a limb of a bird, with the distinction that, in this case, no metastases were observed.
Martin A. Zordan, MV, Michael M. Garner, DVM, Dipl ACVP, Rebecca Smedley, DVM, MS, Dipl ACVP, Dana Neelis, DVM, MS, Dipl ACVR, and Carlos R. Sanchez, DVM, MSc
From the Latin American Association of Zoological Parks and Aquariums, Nuestra Sra. del Rosario 165, Las Condes, Santiago, Chile (Zordan); Northwest ZooPath, 654 W Main St, Monroe, WA 98272, USA (Garner); Diagnostic Center for Population and Animal Health, Michigan State University, 4125 Beaumont Rd, Lansing, MI 48910, USA (Smedley); Animal Imaging, 6112 Riverside Dr, Irving, TX 75039, USA (Neelis); and the Animal Health Department, Fort Worth Zoo, 1989 Colonial Pkwy, Fort Worth, TX 76110, USA (Sanchez).
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Caption: Figure 1. A right wing mass in a Vieilott's fireback pheasant. (A) An ulcerated mass surrounds the elbow region of the wing. (B) Radiographic image of the right wing, showing moderate to marked soft tissue swelling, with osteolysis and a pathologic fracture of the proximal right humerus (arrows). (C) Photomicrograph of the neoplasm showing interlacing bundles (arrows) of neoplastic smooth muscle cells. Hematoxylin and eosin, bar = 150 [micro]m. (D). Photomicrograph of histologic image showing diffuse positive staining reaction for smooth muscle actin (arrow). Immunoperoxidase with hematoxylin counterstain, bar = 200 [micro]m.
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|Title Annotation:||Clinical Report|
|Author:||Zordan, Martin A.; Garner, Michael M.; Smedley, Rebecca; Neelis, Dana; Sanchez, Carlos R.|
|Publication:||Journal of Avian Medicine and Surgery|
|Article Type:||Clinical report|
|Date:||Jun 1, 2017|
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