MESOTHELIOMA- A State of the Art Review
Joanna Koilpillai (5th Year B.VSc Student)
Madras Veterinary College, Vepery High Road, Chennai, Tamil Nadu-600007, India
A mesothelioma is a tumour originating from the mesothelium which is the membranous epithelial tissue that lines the serous cavities of the body. Mesotheliomas, therefore, are the result of abnormal division and replication of mesothelial cells, and their subsequent migration to other sites in the body. The resultant tumours cause numerous non-specific symptoms, such as a history of chronic disease and fluid accumulation in the affected body cavity. In advanced cases, the tumour may even displace internal organs based on their location. In veterinary medicine, mesothelioma has been reported in domesticated animals such as cattle, buffalo, horses, rats, mice, dogs, sheep, hamsters and cats. In birds, it has been reported in Chickens, Ducks, Hawks and Ratites. Mesothelioma was originally considered to be a solely geriatric condition with the average age of diagnosis in dogs being 8.6 years. However, recent studies report cases of Juvenile Mesothelioma in dogs less than one year old with both sexes equally represented.
The perfect chance to study this neoplastic condition came in the form of the following case which was treated at the Veterinary University Peripheral Hospital belonging to Tamil Nadu Veterinary and Animal Sciences University (located in Chennai, Tamil Nadu, India).This essay describes the diagnosis, prognosis and management of mesothelioma.
A 2-year-old Desi hen (Gallus gallus domesticus) was presented with a history of anorexia, distended abdomen and cessation of egg laying for 3 weeks. The owner also complained of frequent straining despite the prolonged pause that the bird was facing. They were rearing a few birds as backyard poultry.
General examination of the bird showed that the bird was emaciated, with a ruffled feather coat and had a visibly distended abdomen. She was sluggish and preferred to sit for extended periods of time, only moving when forced to do so with extremely reluctant movements. Physical examination included palpation and percussion of the abdomen which was suggestive of fluid accumulation. Ascites was radiograpically confirmed. Aspiration of the ascitic fluid revealed adark red, blood-tinged serous fluid as seen in figure 1.
Figure 1: Aspirating the accumulated peritoneal fluid
However, before the treatment could be initiated, the bird collapsed and all efforts to revive her failed. Upon obtaining the owner’s consent, the necropsy was carried out on the same day.
In the necropsy, opening the body cavity revealed an accumulation of 400 millilitres of serosanguinous fluid as shown in figure 2. The reproductive tract was empty and the cloaca showed no traces of egg formation or shell residues, indicating that the bird was experiencing a prolonged pause. The prominent gross lesion noticed within the coelom was multiple, small, firm, whitish nodules that were scattered along the length of the intestine as seen in figure 3. An interesting finding was that the luminal surface of the intestines was unaffected by the nodules which were solely restricted to the mesentery. Samples collected for laboratory diagnosis included aspirated ascitic fluid, impression smears of Intestine, Heart, Liver, Lung, Spleen and Kidney as well as a biopsy of the nodules.
Figure 2: The serosanguinous ascitic fluid (around 400 millilitres) in the peritoneal cavity
Figure 3: Whitish firm nodules seen along the length of the Mesentery and intestinal serosal surface
The condition was tentatively diagnosed as Tuberculosis. Other likely possibilities included Lymphoma, viral diseases causing tumours such as Marek’s Disease, Lymphoid Leukosis and parasite infestation. These hypotheses were based solely on the gross lesions of the nodules along the mesentery and ascites- possibly a sequlae of hypoproteinaemia.
To quote Dr. Balachandran, Professor of Pathology, Madras Veterinary College, “Necropsy is a message sent from the dead to the living.” This was indeed a fine example of that statement. For the laboratory diagnosis along with cytological evaluation revealed that there was no bacteria isolated from the aspirated fluid and all the organ smears showed no cytological alterations. Histopathology of the nodules on the mesentery consisted of Epithelioid cells with acidophilic granular cytoplasm, prominent nucleoli and a vesicular nucleus, suggestive of a mesothelioma.
This effectively ruled out all the possible causes we had initially considered. Thus, based on laboratory results and necropsy findings, the condition was diagnosed definitively as a mesothelioma.
The complete paper is attached ....
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Mesothelioma- A State Of The Art Review