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
Prognosis For Rectal Mass:
- Good
- 17- 55% recurrence
- 18% developed the malignant transformation
- MST Adenoma >2years
- MST Carcinoma in Situ 5-24m
Adenoma & Carcinoma in Situ
Prognosis For Rectal Mass:
- Guarded
- Annular masses - MST 1.6m (worst)
- Nodular/cobblestone - MST 12m
- Pedunculated - MST 32m
Malignant Neoplasia with surgery
Development of which of the following perianal tumors is influenced by androgens?
a. Perianal gland carcinoma
b. Perianal fibroma
c. Perianal gland adenoma
d. Anal gland anal sac adenocarcinoma
c. Perianal gland adenoma
When performing any approach to the rectum, which nerve should be preserved to maintain fecal continence?
Caudal Rectal Nerve
(T/F) Chemotherapy is not very good at preventing local recurrence, since it is a systemic therapy
True
Approximately what percent of dogs with AGASACA will have bilateral disease?
10%
