Lecture 15: Perianal Tumors Flashcards
What is the pathogenesis of perianal gland adenoma?
- Majority of perineal tumors
- Arise from circumanal glands
-
Associated w/ plasma androgen level
- Testosterone favors the development while estrogen does not
How do you create a plan for the diagnosis and staging of a dog or cat with a perianal mass?
Diagnosis:
- Adenoma = Large polyhedral cells (“hepatocytes”)
- Adenocarcinoma = Greater pleomorphism
- Biopsy
What are the treatments for perianal adenoma?
- Castration & surgical with mm to 1cm margins
- Submit testicle and mass for histopathology
- With no castration, IT WILL come back
- Radiation (overkill)
- Cryosurgery
- Electrochemotherapy
Prognosis: - Great
- Monitor for new tumors (esp if not castrated)
What are the treatments for perianal adenocarcinoma?
- locally invasive
- GSD, Artic breeds
- Ulcerated, disgusting looking
Treatments:
- Surgical removal with 1cm margins, removal of metastatic LN +/- castration
- Radiation therapy for incomplete excision
- Electrochemotherapy
Prognosis:
- Tumors >5cm: 11x increased risk of tumor-related death & increased risk of recurrence
- Metastatic disease: 45x increased risk of tumor-related death
- Invasion of underlying structures = increased risk of recurrence
What are the treatments for apocrine gland anal sac adenocarcinoma (AGASACA)?
- Large masses can mimic the gross appearance of hepatoid tumors
- Doesn’t arise from skin
- Very different behavior
- Highly metastatic (regional LN (fecal or urinary obstruction), lungs, liver, spleen)
-
Hypercalcemia in 27% (kidney disease)
- PU/PD
- Muscle weakness - Slow growing
How do you create a plan for the diagnosis and staging of a dog or cat with a rectal mass?
- Benign: Adenomatous polyps
- Malignant: Adenocarcinoma (dogs), Lymphosarcoma (cats)
Clinical signs:
- Hematochezia
- Tenesmus
- Rectal prolapse
- Obstipation
- Abnormal feces
- Dyschezia
- Diarrhea (“end stage”)
Diagnostics:
- Abdominal palpation & rectal exam
- Mass, blood, or stenotic lesion
- Lymph nodes
- Bloodwork (leukocytosis)
- FNA, biopsy, rectal scrape
- Thoracic imaging
- Abdominal US or CT
- Colonoscopy: Used to determine the extent of disease and obtain biopsies
What is the approach for the removal of a rectal mass?
Surgical Considerations:
- Type of lesion: determines margin and depth
- Shape of the lesion: Annular worse prognosis
- Number of lesions: Multiple may not be a surgical candidate (rare 7%)
- Location and size of lesion: Determines surgical approach
- Presence of metastatic disease
Surgical Approaches:
- Simple ligation/electrocautery/cyrosurgery ->only very small pedunculated masses
- Mucosal eversion -> works pretty well
- Advanced procedures: Transanal endoscopic resection and cautery
What Perianal Tumor is uncommon but is very malignant?
Non-glandular tumors
- Anaplastic squamous cell carcinoma
- Melanoma
- Both poor prognosis, highly invasive/metastatic
- Fibroma
- Lipoma
- Hemangiopericytoma
What is the best way to Diagnose AGASACA?
- FNA: neuroendocrine appearance (no need for bx, can complicate surgery)
- DON’T FORT THE LYMPH NODES
What is the treatment for AGASACA?
- Surgical removal of the primary tumor and any metastatic LNs
- +/- radiation (if there is “anything” left behind)
- +/- chemotherapy
Anatomy & Blood Supply:
What are the main things you wouldn’t want to damage?
- Rectal sphincter
- Internal anal sphincter
- External anal sphincter
- Anal sac
- Caud. rectal n.v.a. (may have trouble pooping)
List the Lymph Nodes:
Iliosacral Lymphocenter
- Medial iliac lymph nodes
- Internal iliac lymph nodes
- Sacral lymph nodes
(T/F) Multiple surgeries to remove metastatic lymph nodes increases survival time
True
Surgery for AGASACA:
- Closed anal sacculectomy
- Modified closed technique (remove duct)
Rectal Tumors:
- Arises from smooth m. between serosa and submucosa
- Well-circumscribed intramural mass
- CS generally associated with extraluminal compression
- Good Prognosis
Leiomyoma
