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EMBRYONAL RHABDOMYOSARCOMA IN A ROTHSCHILD’S
GIRAFFE (GIRAFFA CAMELOPARDALIS ROTHSCHILDI)
Margarita Woc-Colburn, D.V.M., Suzan Murray, D.V.M., Dipl. A.C.Z.M., Nancy Boedeker, D.V.M.,
Tabitha Viner, D.V.M., Dipl. A.C.V.P., Michelle L. Fleetwood, D.V.M., Dipl. A.C.V.P., Tony
C. Barthel, Kurt D. Newman, M.D., and Carlos R. Sanchez, D.V.M., MSc.
Abstract: A 3-yr-old male Rothschild’s giraffe (Giraffa camelopardalis rothschildi) presented for acute swelling
caudomedial to the left parietal horn. Following initial diagnostics and supportive treatment, the mass was
surgically resected and intralesional chemotherapy was administered. Despite treatment, the giraffe’s condition
worsened and euthanasia was performed. Gross necropsy revealed neoplastic invasion and destruction of
underlying parietal bone, adjacent horn base, and sinuses, and metastases in the tracheobronchial and mandibular
lymph nodes and lung. Histologically, the tumor was composed of packets of anaplastic round cells.
Immunohistochemical studies further characterized the tumor as an embryonal rhabdomyosarcoma. This is the
first reported case of rhabdomyosarcoma in a giraffe.
Key words: Rothschild’s giraffe, Giraffa camelopardalis rothschildi, embryonal rhabdomyosarcoma.
BRIEF COMMUNICATION
Rhabdomyosarcomas arise from either striated
muscle or muscle progenitor cells.
11,16
These
tumors are classified into three main types based
on histopathologic features; namely embryonal,
alveolar, and pleomorphic. The reported inci-
dence of rhabdomyosarcomas in domestic ani-
mals is less than 1%of all neoplasias, most of
which are reported in dogs.
2,3,6,10,11,15,16
No sex or
age predisposition has been observed; however,
botryoid embryonal subtypes are most common-
ly found in the urinary bladder of juvenile large-
breed dogs.
10,15,16
In zoo animals, rhabdomyosar-
comas have been reported in Baird’s tapir
(Tapirus bairdii), fallow deer (Dama dama)and
white-tailed deer (Odocoileus virginianus).
1,5,9
The
following is the first reported case of an
embryonal rhabdomyosarcoma in a young
Rothschild’s giraffe (Giraffa camelopardalis
rothschildi).
A 3-yr-old, male, 666-kg Rothschild’s giraffe
presented for an acute swelling around the left
parietal horn. Examination revealed a 3-cm
diameter, soft, fluctuant, subcutaneous mass
caudomedial to the left parietal horn. A fine
needle aspirate of the mass was obtained under
chute-restraint. Cytologic analysis revealed pe-
ripheral blood and a presumptive diagnosis of
hematoma was made.
One month after initial presentation, the
giraffe had intermittent bouts of inappetence,
lethargy, and abnormal neck posture. The mass
remained unchanged. A repeat fine needle
aspirate was obtained. Cytology revealed many
clusters of round cells with a moderate amount of
granular cytoplasm suggestive of poorly differ-
entiated sarcoma. Using behavioral restraint,
phlebotomy was performed for hematologic and
serum biochemical evaluation. Complete blood
count and serum chemistry abnormalities includ-
ed mild hyperproteinemia (8.8 g/dl; reference
range 5.9–7.9 mg/dl) and mild hyperfibrinogen-
emia (400 mg/dl; reference range 0–315 mg/dl).
7
Over the next 6 days, no improvement was seen.
Biopsy of the mass was elected.
Standing sedation was performed using detomi-
dine hydrochloride (Dormosedan, Pfizer Animal
Health, New York, New York 10017, USA; 10 mg
i.m.) delivered by hand injection. Sedation was
antagonized with yohimbine (ZooPharm, Lara-
mie, Wyoming 82070, USA; 66 mg i.m. [cumula-
tive]). Analgesic treatment was achieved with
ketoprofen (Ketofen, Fort Dodge Animal Health,
Fort Dodge, Iowa 50501, USA; 300 mg i.m.).
The soft tissue mass contained a soft, fluctuant
region cranially delimited by firm tissue. Two 4-
From the Smithsonian Institution’s National Zoo-
logical Park, 3001 Connecticut Avenue NW, Washing-
ton, D.C. 20008-2598, USA (Woc-Colburn, Murray,
Boedeker, Viner, Barthel, Sanchez); the Department of
Veterinary Pathology, Armed Forces Institute of
Pathology, 6825 16th Street NW, Washington, D.C.
20306, USA (Fleetwood); and the Children’s National
Medical Center, 111 Michigan Avenue NW, Washing-
ton, D.C. 20010-2970, USA (Newman). Present address
(Sanchez): Chicago Zoological Society, Brookfield Zoo,
3300 Golf Road, Brookfield, Illinois 60513, USA.
Correspondence should be directed to Dr. Woc-Colburn
(margarita_woc@yahoo.com). The author(s) prepared
this manuscript as part of their official duties with the
U.S. Government and are unable to assign rights to the
American Association of Zoo Veterinarians.
Journal of Zoo and Wildlife Medicine 41(4): 717–720, 2010
717
mm punch biopsies were obtained from the firm
aspect of the mass. Cytology of a Wright’s-
stained impression revealed a monomorphic
population of round cells with scant cytoplasm.
The biopsy sample was fixed in 10%neutral
buffered formalin and processed routinely for
histology. Histopathology revealed packets of
polygonal cells with indistinct cell borders, small
amounts of fibrillar cytoplasm, and up to five
irregularly round nuclei per cell with finely-
stippled chromatin and variably distinct nucleoli.
Packets of neoplastic cells were supported by a
fibrovascular stroma. The cells often lined the
boundaries of the packets, and cells at the center
of the packets were vacuolated or had lost cell
contact (Fig. 1). The mitotic activity was ap-
proximately 1 per 3400 field. In some areas,
neoplastic cells were more anaplastic; with a loss
of packeting arrangement, more abundant eosin-
ophilic cytoplasm, anisokaryosis, anisocytosis,
and large nucleoli. Immunohistochemical stain-
ing was performed on deparaffinized sections
using the avidin-biotin-peroxidase complex tech-
nique for vimentin (mouse monoclonal antibody,
clone V9, Ventana, Tucson, Arizona 85755,
USA; premixed solution), neuron-specific enolase
(mouse monoclonal antibody, clone E27, Ven-
tana; premixed solution), glial fibrillary acidic
protein (rabbit polyclonal antibody, Dako, Car-
pinteria, California 93013, USA; 1:16,000 dilu-
tion), Melan A (mouse monoclonal antibody,
clone A103, Novocastra, Newcastle NE12 8EW,
United Kingdom; 1:50 dilution), chromogranin
(rabbit polyclonal antibody, Dako; 1:1,600 dilu-
tion), synaptophysin (rabbit polyclonal antibody,
Ventana; premixed solution), muscle-specific ac-
tin (mouse monoclonal antibody, clone HUC1-1,
Ventana; premixed solution), myogenin (mouse
monoclonal antibody, clone F5D, Dako; 1:50
dilution), and myoD1 (mouse monoclonal anti-
body, clone 5.8A, Novocastra;1:50 dilution).
Sections were also stained under identical condi-
tions, with normal rabbit or normal mouse serum,
to serve as negative controls. These immunohis-
tochemical stains were incubated with diamino-
benzidine chromogen (Ventana) and counter-
stained with Mayer hematoxylin.
Strong positivity for actin and desmin was
found in the cytoplasm of approximately 50%of
the neoplastic cells, and nuclei were positive for
myogenin (100%of cells) and myoD1 (75%of
cells). Nearly 100%of the neoplastic cells were
also nonspecifically positive for vimentin in
the cytoplasm, as well as for S-100 protein
within nuclei. These immunohistochemical find-
ings, coupled with the histomorphology of the
mass, indicated embryonal rhabdomyosarco-
ma.
4,14,16
Surgical excision of the mass, followed by
intralesional chemotherapy under general anes-
thesia, was performed. The giraffe was immobi-
lized with medetomidine hydrochloride (Zoo-
Pharm; 6 mg), ketamine hydrochloride (Zoo-
Pharm; 400 mg) and A3080 (ZooPharm; 3 mg)
i.m. via hand injection. Muscle relaxation was
maintained with guaifenesin (Vedco, St. Joseph,
Missouri 64503, USA; 12,500 mg i.v. continuous
drip). Anesthesia was antagonized with naltrex-
one (ZooPharm; 50 mg i.m.) and atipamezole
(30 mg i.v. and 30 mg i.m.).
Right and left oblique skull radiographs
revealed lytic changes of the parietal bone
underlying the soft tissue mass. To control
intracranial swelling, dexamethasone (VetOne,
Meridian, Idaho 83680, USA; 500 mg i.v.) and
prednisolone sodium succinate (Solu-delta-cortef,
Pfizer Animal Health; 1,000 mg i.m.) were
administered.
The soft tissue mass located caudal to the left
parietal horn measured 10 310 36 cm. Wide
lateral surgical margins were obtained. On the
basilar aspect, the mass extended to the parietal
bone and full surgical excision was not possible.
Intralesional chemotherapy with 5-fluorouracil
(Fluoroplex, Allergan Inc., Irvine, California
92612, USA; 300 mg) was given. Histopathology
revealed that neoplastic cells extended to all cut
borders of the tissue submitted.
Over the next 11 days, the giraffe was treated
supportively. Five days postoperatively, a new
Figure 1. Embryonal rhabdomyosarcoma of a
Rothschild’s giraffe. Neoplastic polygonal cells are
arranged in packets or sheets. Mitotic figures are
present at a rate of approximately 1 per 3400 field.
H&E, 3200.
718
JOURNAL OF ZOO AND WILDLIFE MEDICINE
mass 2 34 cm developed at the incision site.
Eleven days after surgery, the giraffe became
ataxic, obtunded, and developed bilateral hori-
zontal nystagmus. Brief improvement of vestib-
ular signs was seen with diphenhydramine
(Benadryl, Baxter Healthcare, Deerfield, Illinois
60015, USA; 500 mg i.m.) administration.
Euthanasia was elected due to a grave prognosis.
On gross necropsy, a poorly healed incision site
with an 8 3834 cm hematoma subadjacent to
the incision was noted between the left parietal
horn and pinna. Below the hematoma, there was
a10310 34 cm irregular, soft, pale tan mass
infiltrating the adjacent skeletal muscle, salivary
gland, and bone. There was a 4 34cmareaof
complete bone loss in the base of the parietal
horn and the adjacent parietal bone covering the
parietal sinus. The bone between the parietal
sinus and the brain, at the level of the left cerebral
cortex and cerebellar hemisphere, was completely
lost. The tumor filled the sinus between the areas
of bone loss, compressed the left side of the
cerebellum, and was attached to the meninges of
the caudal left cerebral hemisphere (Fig. 2). The
caudal left cerebral cortex was malacic. There
were multifocal, large hemorrhages in the caudal
left cerebral cortex, the dorsal surface of the
brainstem, and between the left side of the
brainstem and the ventral aspect of the cerebel-
lum. Enlargement of the left mandibular lymph
node, due to tumor metastasis, was present.
There were numerous firm, tan nodules that were
up to 2 cm in diameter throughout the lung.
Tissues were fixed in 10%neutral buffered
formalin, processed routinely, and stained with
hematoxylin and eosin (H&E). Histopathology
revealed that the neoplasm previously described
had eroded the skull and caused extensive
malacia and gliosis of the adjacent gray and
white matter. Neoplastic cells focally infiltrated
the meninges. Tumor cells had also embolized to
the spinal cord vasculature in the area of C1–2.
Based on the histopathology and immunohisto-
chemistry, a diagnosis of embryonal rhabdomyo-
sarcoma with metastasis to the lung, mandibular,
and tracheobronchial lymph nodes was made.
In humans, embryonal rhabdomyosarcomas
are the second most-common malignant head
and neck tumor (18%) in the pediatric popula-
tion.
14
Those found along the parameningeal sites
have a poor prognosis, as 35%of the patients
develop metastases into the meninges and the
central nervous system.
6
In contrast, very few
embryonal rhabdomyosarcomas have been re-
ported along the head and neck of animals.
1–3,5,6
Several of these have been reported to affect
parameningeal sites such as the paranasal sinus,
nasal cavity, and infratemporal fossae, with
metastases to the meninges.
1,2,6,10
This giraffe’s
tumor may have originated in the parameningeal
region. Similar to other parameningeal rhabdo-
myosarcomas, it could have spread to the
meninges and surrounding skeletal muscle.
In both humans and domestic animals, treat-
ment of choice is wide surgical excision of tumor
followed by radiation or chemotherapy.
12,14
A
five-fluorouracil, a pyrimidine antagonist, has
been used in some protocols with varying
success.
12
However, survival rates of patients with
embryonal rhabdomyosarcoma, even with che-
motherapy, rapidly decrease with the presence of
metastasis.
14
Areas of necrosis that involved large
swaths of neoplastic cells with enmeshed blood
vessels were observed on histopathology of the
tumor. This could indicate that intralesional
chemotherapy had a limited effect on tumor
control.
Few spontaneous tumors have been reported in
giraffes. These include a pelvic chondrosarcoma
and a teratoma of the umbilical cord.
8,13
At the
National Zoological Park, a thyroid adenoma
and uterine leiomyoma have also been observed
(unpubl. data). None of these have been reported
to cause neurologic signs.
Acknowledgments: The authors would like to
thank the pathologists and technicians at the
Armed Forces Institute of Pathology who per-
formed the immunohistochemical stains. In
Figure 2. Brain from a 3-yr-old Rothschild’s gi-
raffe. The embryonal rhabdomyosarcoma that extended
through lysed calvarial bone and sinus distorts and
displaces the cerebellum and adjacent cerebrum. Bar 5
1cm.
WOC-COLBURN ET AL.—RHABDOMYOSARCOMA ROTHSCHILD’S GIRAFFE
719
addition, the authors would like to thank Drs.
Mitch Bush and Scott Citino for their assistance
with the giraffe’s immobilization.
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Received for publication 26 September 2009
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