Results
AFIP Wednesday Slide Conference - No. 30
28 May 1997
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- Conference Moderator: Dr. Thomas P. Lipscomb
Diplomate, ACVP
Department of Veterinary Pathology
Armed Forces Institute of Pathology
Washington, D.C. 20306-6000
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Case I - 388 (AFIP 2578783)
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- Signalment: 5-year-old, castrated male, lop-eared
rabbit.
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- History: In early January, this rabbit developed ocular
discharge and was treated for Pasteurella infection. Soon after,
the owner noticed a lump below the philtrum which was biopsied
in mid-January and diagnosed as ameloblastoma. The ocular discharge
never resolved, and the mass began growing back by late January
and gradually deformed the right side of the face. Sneezing worsened
and by
mid-February, the rabbit began having breathing difficulty and
was euthanized.
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- Gross Pathology: A 1x1x2 cm exophytic mass is present
within the oral cavity just below the nasal philtrum. The right
nasal bones are markedly convex from the nasal planum to a point
just rostral to the eye. The convex region has marked crepitus
on palpation, and measures 2x2x3 cm with the skin removed. Longitudinal
section of the skull reveals a mass associated with the oral
mass. There is bone destruction of the maxilla, nasal bones,
hard palate and turbinates. The mass is soft with numerous mineralized
foci.
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- Laboratory Results: None.
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- Contributor's Diagnosis and Comments: Ameloblastoma
- maxillary gingiva, nasal philtrum, maxilla and nasal cavity,
extensive, asymmetric.
- Ameloblastoma is a rare neoplasia of tooth root origin and
has never been reported in the rabbit. The tumor is locally invasive
and locally destructive to bone. Metastasis has not been reported.
The histologic criteria to be alerted to are the irregular islands
with peripheral palisading columnar cells with polarized nuclei
away from the basement membrane, and the stellate reticulum within
the central region.
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- AFIP Diagnosis: Nasal cavity: Ameloblastoma, with
hard substance, lop-eared rabbit, lagomorph.
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- Conference Note: Odontogenic neoplasms are uncommon.
Teeth develop from two embryonic tissues. The enamel cap is derived
from the dental lamina, which is an invagination of squamous
epithelium from the lining of the buccal cavity. All other parts
of the tooth, including dentin, cementum, and pulp, arise from
the embryonic mesenchyme. Classification of odontogenic neoplasms
is based on the inductive concept of odontogenesis: ameloblastic
epithelium induces differentiation of dental papilla mesenchyme
into odontoblasts, which forms dentin. The dentin induces ameloblasts
to form enamel.
- During normal tooth development, an epithelial ridge (dental
lamina) develops, grows, and extends into the underlying mesenchymal
tissue. The invading epithelium continues to proliferate as a
solidly cellular mass forming the cap stage. There is condensation
of the mesenchymal component (dental papilla) at its base. Both
the epithelium and dental papilla mesenchyme continue to grow
convert the epithelium into a bell-like structure in the bell
stage. The epithelium, now an enamel organ, is divisible into
distinct regions. The inner enamel epithelium is composed of
columnar ameloblasts. The center of the enamel organ is the stellate
reticulum. The ameloblasts are separated from the dental papilla
by a basement membrane. The region of contact between the stellate
reticulum and ameloblasts is occupied by cuboidal cells (stratum
intermedium). As the tooth develops, the stellate reticulum (enamel
pulp) atrophies and the outer enamel epithelium collapses upon
the inner enamel epithelium. The dental papilla is entrapped
within the confines of the enamel organ. A thin layer of columnar
cells (odontoblasts) differentiates from the mesenchyme along
the inner surface of the basement membrane; the remaining papilla
becomes the pulp. A condensed mass of connective tissue (dental
sac) surrounds the enamel organ and dental papilla, giving rise
to alveolar bone, the periosteum surrounding the root, cementoblasts,
and the periodontal membrane. (Banks, 1993)
- In animals, ameloblastomas are reported more commonly in
dogs and cattle than in cats and horses and are most frequently
located in the mandible. They tend to be slow growing and invasive,
resulting in extensive bone destruction. They do not metastasize
but tend to recur after incomplete excision. Histologically,
ameloblastomas are composed of islands and anastomosing cords
of epithelium with peripheral palisades of polarized, cuboidal
to columnar cells that resemble the inner enamel epithelium and
enclose stellate reticulum-like tissue. There may be occasional
keratinization. There may be cysts originating from the degeneration
of centers of epithelial islands or from stromal degeneration.
In animals, the presence of dentin or osteodentin-like hard substance
has been noted in ameloblastomas.
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- Contributor: University of California - Davis, Veterinary
Medical Teaching Hospital, Davis, CA
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- References:
1. Banks WJ (editor): Applied Veterinary Histology. Third
edition, Mosby Year- book, pp. 331-336, 1993.
- 2. Dubielzig, RR, Thrall, DE: Ameloblastoma and keratinizing
ameloblastoma in dogs. Vet Pathol 19:596-607, 1982.
3. Shafer, WG: A textbook of oral pathology, WB Saunders, pp
308-314, 1983.
- 4. Jubb KVF, Kennedy PC, Palmer N (eds): Pathology of Domestic
Animals. Vol. 2, pp 21-26, 1993.
- 5. Moulton, JE (editor): Tumors in Domestic Animals. 3rd
ed., Univ. of Calif. Press, Berkeley, pp. 364-370, 1990.
- 6. Gardner DG: Ameloblastomas in the horse: a critical review
and report of an additional example. J Oral Pathol Med 23:41-4,
1994.
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- International Veterinary Pathology Slide Bank:
Laser disc frame #3336, 9349, 19928-9.
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Case II - D95-203 (AFIP 2551585)
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- Signalment: 8-month-old, female, ferret (Mustela furo).
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- History: This ferret was obtained from a commercial
vendor, where it had been maintained under artificial lighting
conditions consisting of 16 hours of light and 8 hours of darkness.
These lighting conditions were continued after the animal was
received from the vendor. Weight loss occurred over the next
18 days, and the animal was submitted for a diagnostic necropsy.
The animal had not been experimentally manipulated during this
time.
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- Gross Pathology: The animal was moderately thin, with
little body fat. The uterus was enlarged.
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- Laboratory Results: None.
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- Contributor's Diagnosis and Comments:
1. Uterus: Endometrial hypertrophy with symplasma formation
(pseudopregnancy), Mustela furo.
2. Uterus: Endometritis, acute, multifocal, mild.
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- Pseudopregnancy in the ferret can develop following a sterile
mating, or as result of hormonal imbalance caused by reduced
light intensity one month before breeding. The history of this
ferret prior to receipt from the vendor is unknown.
- Histological changes in the endometrium are the same in the
pregnant and pseudopregnant uterus. Features of the endometrium
in the present case include dilated glands containing large amounts
of secretory material, marked enlargement of luminal and glandular
epithelial cells with extreme karyomegaly, symplasma formation,
and sloughing of symplasmic masses into the uterine lumen. There
are also small accumulations of neutrophils within some dilated
glands. These features are similar to the appearance of the endometrium
20 to 25 days following breeding. Symplasma formation occurs
as the most superficial hypertrophied epithelial cells lose their
integrity and form masses of protoplasm containing whole or fragmented
nuclei. The duration of pseudopregnancy is identical to pregnancy
(40-42 days). The endometrium breaks down between day 35 and
day 40, and resembles the anestrous state by day 45.
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- AFIP Diagnosis:
- 1. Uterus: Endometrial hypertrophy with symplasma formation,
ferret (Mustela furo), mustelid.
2. Uterus: Endometritis, acute, multifocal, mild.
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- Conference Note: In ferret uteri, the pre-implantation
period is characterized by general growth of the tissue and moderate
secretory activity. At the time of implantation, the luminal
epithelium undergoes hypertrophy and hyperplasia and shows much
secretory activity. This area of altered activity sweeps progressively
toward the gland fundi, and the epithelium behind it becomes
progressively enlarged forming symplasmic masses. In the ferret,
symplasma formation occurs in all regions of the uterus in both
pregnant and pseudopregnant animals, in contrast to other carnivores
that have been studied in which it develops only at implantation
sites.
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- Contributor: The Procter & Gamble Company, Miami
Valley Laboratories, P.O. Box 398707, Cincinnati, OH 45239-8707.
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- References:
1. Buchanan GD: Reproduction in the ferret (Mustela furo).
I. Uterine histology and histochemistry during pregnancy and
pseudopregnancy. Am J Anat 118(1): 195- 216, 1966.
- 2. Fox JF: Biology and Diseases of the Ferret. Lea &
Febiger, Philadelphia, 1988.
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- International Veterinary Pathology Slide Bank: None.
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Case III - 1000194 (AFIP 2550496)
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- Signalment: Hare (Lepus europaeus), male, adult
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- History: The animal was shot in January 1994 together
with six other hares from the same area in order to find out
possible causes of the progressive diminishing of the hare population
in Germany. The epidemiological study included parasitological,
serological, toxicological and histopathological investigation
on 88 hares from 4 adjacent areas altogether. Tissues from lungs,
heart, pancreas, spleen, kidneys, adrenals, thyroid gland, brain
and testes were submitted for histopathological examination.
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- Gross Pathology: Macroscopic changes in this animal
were restricted to the liver which exhibited multiple firm yellowish
grey patches.
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- Laboratory Results: Serologically, antibodies to Brucella
spp., Leptospira spp. and Pasteurella tularensis were not detected.
The Coxiella burnetii titer was suspicious (1:10). A hemagglutination
inhibition test for rabbit hemorrhagic disease virus antibodies
showed a positive result (titer 1:80). The parasitological investigation
revealed eggs of Capillaria hepatica in the liver, as well as
low contents of Trichostrongylus retortaeformisand Trichuris
leporis in the intestine.
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- Contributor's Diagnosis and Comments: Liver: hepatitis,
granulomatous, multifocal, chronic, severe, with eggs of Capillaria
hepatica and caseous necrosis within granulomas.
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- Sections of the liver contain multiple coalescing granulomas
characterized by central partially calcified caseous necrosis,
cellular debris and granulocytes, epithelioid macrophages and
giant cells. Lesions are surrounded by a zone of fibroblast proliferation
and encapsulated by fibrous connective tissue. In adjacent areas,
bile duct proliferation can be observed. In the centers of the
granulomas, either multiple ovoid, intact parasite eggs with
obvious polar caps or their disintegrated remnants are found
in an intracellular or extracellular localization.
- Additionally, two other hares from the same areas also showed
a Capillaria hepatica infection. The remaining 85 animals examined
within this study over a period of three years, were not affected.
The reason for the local and temporary limitation of the infection
remains unknown.
- Rats and mice are the usual hosts of Capillaria hepatica.
The parasite shows a direct life cycle with both female and male
worms in the liver parenchyma. Eggs remain in the liver until
the host is devoured or the liver undergoes postmortem decomposition.
Embryonation occurs in the soil (CONLOGUE et al., 1979). Antemortem
diagnosis is only possible by liver biopsy. The parasites are
not highly pathogenic. Their importance is gathered by their
ability to infect other mammals. Sporadically carnivores [dogs
(see: AFIP 2415684), cats, coyotes), horses, hares, hedgehogs,
and humans] may be affected (BRANDER et al., 1990;PANNENBECKER
et al., 1990).
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- AFIP Diagnosis: Liver: Granulomas, eosinophilic, multiple,
coalescing, with bioperculate barrel-shaped nematode eggs, hare
(Lepus europaeus), lagomorph, etiology consistent with Capillaria
hepatica.
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- Conference Note: Capillaria hepatica is apparently
a widespread parasite of wild mice and rats; up to an 80% incidence
has been reported in urban rats in some areas. Infection is usually
inapparent in rodents, and is uncommon in laboratory-reared animals
because of the unusual requirements of the life cycle. This parasite
is occasionally seen in dogs and monkeys, has been described
in several other wild animal species (beavers, muskrats, hares,
and peccaries), and sometimes infects man. Capillaria spp. are
aphasmids and are classified in the group Trichinellina, which
includes both Capillariidae and Trichuridae; these aphasmids
are unique among nematodes because they have stichosomes (a series
of glands along their esophagus) and one or more bacillary or
hypodermal bands (hypodermal gland cells that have pores through
the cuticle) that give the cuticle a striated appearance, and
distinguish it from the other trichurids. Their musculature is
coelomyarian, polymyarian but may be inapparent. The intestine
is composed of uninucleate cuboidal to columnar cells. Eggs are
bioperculate, barrel- shaped, thick- shelled and the outer shell
layer is striated.
- Microscopically, both adult nematodes and masses of eggs
can be seen. The adults cause some traumatic hepatitis and the
eggs provoke the development of granulomas. The hepatitis may
be severe enough in some animals to result in cirrhosis. In primates,
the disease is severe and has been associated with some deaths.
- C. hepatica is of public health significance where children
play in rat-infested areas. Clinical manifestations in humans
resemble visceral larva migrans. There is eosinophilia and hepatomegaly,
and acute or subacute hepatitis.
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- Contributor: Institut für Veterinär-Pathologie,
der Unversität Leipzig, Margarete- Blank-Str. 4, D-04103,
Leipzig.
- References:
1. Brander P, Denzler T, Henzi M: Capillaria hepatica in
a dog and hedgehog. Schw Arch Teirheilk 132:365-370, 1990.
- 2. Conlogue G, Foreyt W, Adess M, Levine H: Capillaria hepatica
(Bancroft) in select rat populations of Hartford, Connecticut,
with possible public health implications. J Parasitol 65:103-108,
1979.
- 3. Farhang-Azad A: Ecology of capillaria hepatic (Bancroft
1893) (Nemotoda). 1. Dynamics of infection among Norway rat populations
of the Baltimore Zoo, Baltimore, MD J Parasitol 63:117-122, 1977.
- 4. Pannenbecker J, Miller TC, Müller J, Jeschke R: Severe
Capillaria hepatica infestation in a young child. Monatsschr
Kinderheilkd 138:767-771, 1990.
- 5. Chitwood, M, and Lichtenfels, JR: Identification of parasitic
metazoa in tissue sections. Exp Parasitol 32: 407-519, 1972.
- 6. Jubb KVF, Kennedy PC, Palmer N (eds): Pathology of Domestic
Animals, Fourth edition, Vol. 2, Academic Press, p. 376, 1993.
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- International Veterinary Pathology Slide Bank:
Laser disc frame #4131, 19337-40.
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Case IV - 95P1056 (AFIP 2551662)
- Signalment: 5-year-old, female, Holstein, bovine.
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- History: The herd has lost 18 cattle in the last 4
to 5 weeks. This cow calved 6 days ago and was down this morning.
She died during calcium therapy.
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- Gross Pathology: There were multiple and numerous
linear and punctate erosions and ulcers in the distal ½
of the esophagus. There were petechia in the abomasum. The ileum
and colon were filled with serosanguineous fluid containing clots
of blood and fibrin. The liver was pale and swollen. The uterine
mucosa was diffusely gray, thickened, necrotic and foul smelling.
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- Laboratory Results: Florescent antibody test for bovine
viral diarrhea (BVD) virus on esophagus and ileum was positive.
Culture of Peyer's patches and colon yielded Salmonella serogroup
E and liver yielded E. coli and Pasteurella hemolytica.
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- Contributor's Diagnosis and Comments:
- 1. Esophagitis, necrotizing, multifocal, acute, moderate.
2. Enteritis, necrohemorrhagic, diffuse, acute, severe with thrombosis
and lymphoid (Peyer's patch) necrosis due to infection with BVD
virus and Salmonella serogroup E.
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- The cow had classical mucosal disease and was also infected
with Salmonellaserogroup E. Probably the cow was persistently
infected with a non-cytopathic strain of bovine viral diarrhea
virus and was recently exposed to a cytopathic BVD strain or
a cytopathic mutant of the persisting strain. Two of the other
affected herdmates were also positive for BVD virus and were
infected with Salmonella serogroup E. By genomic typing, BVD
isolates are divided in BVD VIRUS type 1 and type 2. Both cytopathic
and non-cytopathic isolates are found among each subtype.
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- AFIP Diagnosis:
- 1. Small intestine: Enteritis, necrotizing, subacute, fibrinosuppurative
and hemorrhagic, transmural, severe, with necrotizing vasculitis,
thrombosis, lymphoid necrosis and depletion, bacilli and fungal
hyphae, Holstein, bovine.
2. Esophagus: Esophagitis, necrotizing, subacute, multifocal,
moderate, with intra- epithelial cleavage vesicles, Holstein,
bovine.
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- Conference Note: The histopathologic findings are
characteristic of mucosal disease. In addition to the evidence
of viral and bacterial infection, a section stained by the GMS
method demonstrated vaso-invasive fungal hyphae morphologically
consistent with Aspergillus sp. The fungal hyphae are very difficult
to discern in the HE stained sections. A Gram's stain demonstrated
gram-negative bacilli wihin the inflamed intestinal wall. A variety
of opportunistic infections have been reported in cases of mucosal
disease.
- Bovine viral diarrhea virus infection produces a wide spectrum
of disease including subclinical infection (most common), bovine
virus diarrhea, immunosuppression, infertility, abortion and
mummification, congenital defects, immunotolerance and persistent
infection, and acute and chronic mucosal disease.
- The principle routes of infection are via inhalation or ingestion
of infected saliva, oculonasal discharge, urine and feces. Transmission
may also occur through infected semen, uterine secretions, amniotic
fluid, placenta or via contaminated hypodermic needles. Blood-feeding
flies can transmit the infection experimentally.
- The virus can cross the bovine placenta and fetal blood-brain
barrier and infect the fetus; a wide variety of developmental
abnormalities and/or fetal death may result. Cows usually remain
clinically normal; however, fertility is transiently reduced.
Fetal damage is probably due to specific interference with tissue
differentiation, maturation, and growth, since there are no placental
lesions.
- BVD virus is antigenically related to the Hog Cholera virus
of pigs and the Border Disease virus (Hairy Shaker Disease) affecting
sheep.
Contributor: Iowa State University, Department of Pathology,
South 16th Street, Ames IA 50011.
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- References:
1. Boling S. In Report of the committee on infectious diseases
of cattle, bison and llama. Proc USAHA Ann mtg. Grand Rapids,
MI, 1994, pg 266-268.
- 2. Baker JC. Bovine viral diarrhea virus: A review. JAVMA
190:1449-1458, 1987.
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- International Veterinary Pathology Slide Bank:
Laser disc frame #1302, 1328, 1561, 2030, 2031, 2668, 2847,
2848, 3511, 3512, 8868.
- Lance Batey
Captain, VC, USA
- Registry of Veterinary Pathology*
Department of Veterinary Pathology
Armed Forces Institute of Pathology
(202)782-2615; DSN: 662-2615
Internet: Batey@email.afip.osd.mil
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- * The American Veterinary Medical Association and the American
College of Veterinary Pathologists are co-sponsors of the Registry
of Veterinary Pathology. The C.L. Davis Foundation also provides
substantial support for the Registry.
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