Uterine Adenocarcinoma in a Rabbit


Uterine Adenocarcinoma in a Rabbit

History: An 11 year old intact female rabbit  had a chronic history of Pasteurella multocida snuffles and head tilt which had resolved.   Her owner noticed she started to have increased abdominal component of respiration which progressed to open mouth breathing.  A mass was palpated in the caudal abdomen during examination.

Gross Necropsy:

The lungs were almost completely replaced by large numbers of individual to coalescing firm white nodules ranging in size from 0.5 cm to 3 cm in diameter and projecting 1-2 cm from the lung surface. On cut surface the nodules were firm and homogeneously white.

Lungs. liver, in situ: Multifocal tan firm nodules replace most of the lung tissue

Lungs. liver, in situ: Multifocal tan firm nodules replace most of the lung tissue

Lungs, liver, closer view

Lungs, liver, closer view

Lungs (with pluck) removed

Lungs (with pluck) removed

A 3.5 cm x 2 cm x 1 cm elliptical mass was present in the wall of the right uterine horn located approximately 1 cm from the ovary. The mass was irregular and composed of firm white nodules and softer grey areas.

Uterus and uterine horns: One horn is enlarged with a transmural mass

Uterus and uterine horns: One horn is enlarged with a transmural mass

Uterine horn: Closer view of mass

Uterine horn: Closer view of mass

Uterine horn: Lumen opened showing thickened uterine wall

Uterine horn: Lumen opened showing thickened uterine wall

The liver had multifocal firm white nodules (1.5 cm to 0.5 cm in diameter) scattered throughout the parenchyma.

An 11 year 9 month old intact female rabbit was presented for necropsy on 9/19/08. This doe had a
chronic history of Pasteurella multocida snuffles and head tilt which had resolved. On 9/18/08 her
owner noticed she started to have increased abdominal component of respiration which progressed to
open mouth breathing on 9/19/08. She had no previous indication of respiratory distress. A mass
palpated in the caudal abdomen during examination. She was euthanized at 2:10 pm and sent in for
necropsy.

Histopathology:

Uterus:  The myometrium was infiltrated by a neoplasm composed of epithelial cells forming tubules and acini.

Uterine wall: The myometrium is invaded by a neoplasm forming acini (neoplastic endometrial glands)

Uterine wall: The myometrium is invaded by a neoplasm forming acini (neoplastic endometrial glands)

Uterus: Closer view of neoplastic endometrial glands

Uterus: Closer view of neoplastic endometrial glands, the neoplastic cells are separated by fibrous tissue

Uterus: Close up of neoplastic cells

Uterus: Close up of neoplastic cells

Lung and Liver:  The neoplastic cells in the lung and liver resembled those in the uterus, however they formed solid sheets rather than acini and were more anaplastic with marked anisocytosis and anisokaryosis.

Lung: Low power view showing multiple=

Lung: Low power view showing multiple individual nodule of metastatic uterine adenocarcinoma

Liver:  A nodule of metastatic neoplastic cells compresses adjacent liver tissue

Liver: A nodule of metastatic neoplastic cells compresses adjacent liver tissue

Comment:

Uterine adenocarcinoma arises from endometrial glands, and is the most common spontaneous neoplasm in Rabbits.  The incidence of this neoplasm increases to 80% of animals 5-6 years and older in Oryctolagus cuniculus. The etiology of the neoplasm is unknown, however some reports implicate estrogen as a related factor.  A recent report in Vet Pathol found that papillary adenocarcinomas were negative for both estrogen and progesterone receptors, but tubular/solid neoplasms were positive for either estrogen or progesterone receptors.  The authors suggest that there may be a separate pathogenesis between these two forms of the neoplasm.

These tumors usually are multinodular and involve both uterine horns.  They may metastasize to the lung and liver most commonly and become  implanted on serosal surfaces of the abdominal organs.

Reference:

Percy, DH and Barthold, SW. Chapter 6 Rabbit in Pathology of Laboratory rodents and rabbits, 3rd edition.  p 253.  Blackwell Publishing, 2007.

M. G. Asakawa, M. H. Goldschmidt, Y. Une, and Y. Nomura. The Immunohistochemical Evaluation of Estrogen Receptor-{alpha} and Progesterone Receptors of Normal, Hyperplastic, and Neoplastic Endometrium in 88 Pet Rabbits. Vet Pathol March 2008 , 45: 2: 217-225, doi:10.1354/vp.45-2-217.

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About Brian

Anatomic Pathologist, VetPath Services, Stone Ridge, NY- musculoskeletal, oral/dental, and sinonasal diseases
This entry was posted in Necropsy Cases and tagged , , , . Bookmark the permalink.

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