Difference between revisions of "Anal Sac Adenocarcinoma"
| Line 14: | Line 14: | ||
===Rectal examination=== | ===Rectal examination=== | ||
| − | Tumours of the anal sac can be detected by digital rectal palpation of the anal sac and assosiated structures | + | Tumours of the anal sac can be detected by digital rectal palpation of the anal sac and assosiated structures, this must be performed with care as frequently the tumours are small and unilateral. Best carried out under general anaesthetic with manual compression of the caudal abdomen towards the rectum. |
===Biochemistry=== | ===Biochemistry=== | ||
| Line 23: | Line 23: | ||
===Thoracic radiographs=== | ===Thoracic radiographs=== | ||
| − | At least two views to check for thoracic metastases. | + | At least two views to check for thoracic metastases. |
===Abdominal imaging=== | ===Abdominal imaging=== | ||
| − | Caudal lateral abdominal radiographs or abdominal ultrasound to assess the medial iliac lymph nodes for metastases. When enlarged | + | Caudal lateral abdominal radiographs or abdominal ultrasound to assess the medial iliac lymph nodes for metastases. When enlarged they displace the rectum ventrally. |
| − | ===Needle biopsy=== | + | Sites of metastasis include the liver, spleen, abdominal lymph nodes and the lungs. |
| + | |||
| + | ===Needle biopsy and Histopathology=== | ||
Guided by ultrasound to aspirate the effected lymph nodes. | Guided by ultrasound to aspirate the effected lymph nodes. | ||
Revision as of 09:36, 18 July 2010
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Description
A highly malignant neoplasia that readily metastasizes to the medial iliac lymph nodes. Around 50% may lead to paraneoplastic hypercalcaemia due to parathyroid hormone-related peptide. The tumours can be between 1 and 10cm in size and 50% of them will metastasize.
Signalment
Have only been confirmed in dogs although they may occur in cats. Typically older bitches (greater than 10 years) are affected (90% of cases) however male dogs are occasionally affected. Predisposed dog breeds include the german shepherd dog, cocker spaniel, welsh spaniel and standard dachshund.
Diagnosis
History and Clinical Signs
See Anal Sac Disease - General
Also: Obstipation due to enlarged internal iliac lymph nodes and Pernieal swelling. Additionally signs of Hypercalcaemia including polydipsia, polyuria, anorexia and weight loss.
Rectal examination
Tumours of the anal sac can be detected by digital rectal palpation of the anal sac and assosiated structures, this must be performed with care as frequently the tumours are small and unilateral. Best carried out under general anaesthetic with manual compression of the caudal abdomen towards the rectum.
Biochemistry
To assess:
- Calcium
- Phosphate
- Renal function
Thoracic radiographs
At least two views to check for thoracic metastases.
Abdominal imaging
Caudal lateral abdominal radiographs or abdominal ultrasound to assess the medial iliac lymph nodes for metastases. When enlarged they displace the rectum ventrally.
Sites of metastasis include the liver, spleen, abdominal lymph nodes and the lungs.
Needle biopsy and Histopathology
Guided by ultrasound to aspirate the effected lymph nodes.
Treatment
The treatment of choice is surgical excision if the patient is normocalcaemic without any metastases. The success will depend upon the size of the mass.
Adjuvant radiotherapy
Can reduce the local recurrence and used if excision is incomplete. However it may lead to radiation-induced colitis.
Palliative chemotherapy
Using platinum or anthracycline can lead to the primary tumour shrinking before surgical excision.
Treatment of Hypercalcaemia
High fluid rates of 0.9% saline to diurese calcium. Furosemide should be administered (2mg/kg intravenously) once the patient in normocalcaemic.
Prognosis
Potential postoperative complications include infection, wound dehiscence, faecal incontinence and in 25% of cases, local recurrence. Hypercalcaemia reoccurs in 35-50% of cases due to metastases. Serum calcium levels should therefore be reguarly along with evidence of mass regrowth. Post-op survival ranges between 2 and 39 months with the average being 8 months
References
Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA
Merck & Co (2008) The Merck Veterinary Manual
Dobson, J.M. and Lascelles, B.D.X. (2003) BSAVA Manual of Canine and Feline Oncology (2nd Edition) BSAVA