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, closer view

 

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

Uterine horn: Closer view of mass

 

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)

 

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

 

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 individual nodule of metastatic uterine adenocarcinoma

 

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.  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.