Anal Disease Flashcards
How do you identify the dentate/pectinate line? Above = internal hem, Below = external hem
Anal valves and bases of anal columns. Microscopically, transitions from mucocutaneous junction between nonkeratinizing squamous mucosa and keratinizing squamous epithelium.
Innervation: SOMATIC below, AUTONOMIC above.
What is the arterial blood supply to the anal region?
Proximal (above dentate) = superior rectal artery / superior rectal vein (IMV) and middle rectal vein (iliacs)
Distal = inferior rectal branch of PUDENDAL artery / inferior hemorrhoidal vessels (iliac)
What is the lymphatic drainage of the anal region?
Proximal (above dentate) = mesorectal, internal iliac, inferior mesenteric nodes
Distal = inguinal nodes
What is the incidence of anal cancer?
2.6% of GI malignancies.
Histologic variants of anal squamous neoplasms?
Cloacogenic
Basaloid
Epidermoid
Mucoepidermoid
All need Nigro.
Main HPV variants that cause anal squamous cell carcinoma?
16 and 18.
What is condyloma acuminata?
Anal warts. Mostly 6 and 11. Flesh colored papules that itch.
How do you treat condyloma acuminata?
Imiquimod cream, podophyllotoxin, 5-FU, sinecatechins clear to 40-60% especially in smaller lesions.
If fails, try 80-90% trichoroacetic acid TCA (in office), cryotherapy, or fulguration/excision.
If very large, surgical excision.
if > 50% circumference, need to stage to avoid stenosis
What is the recurrence rate of condyloma after treatment?
20-40%.
What is Buschke-Lowenstein tumor?
Verrucous carcinoma or giant condyloma acuminatum; with very high risk of fistula/abscess formation. Spreads laterally (doesn’t really metastasize). HPV 6, 11. Treat with WLE.
What is the Bethesda classification in the setting of AIN?
ASCUS, LSIL (AIN I), HSIL (AIN II/III), atypical squamous cells that cannot exclude HSIL.
What cyclin dependent kinase inhibitor is overexpressed in HPV associated carcinogenesis?
P16
How do you screen for anal SCC in high risk population?
Annual anal pap smear with high resolution anoscopy (with 3% acetic acid solution or Lugol’s) for ASCUS or dysplasia.
How do you treat LSIL?
Nothing, can just surveillance q3-6 mos with pap +/- HRA
How do you treat HSIL?
Topical 5% Imiquimod
Topical 5% 5-FU
TCA
should be adjuncts to photodynamic therapy, RF ablation, infrared coagulation, electrocautery.
What is superficially invasive squamous cell carcinoma of the anus?
Minimally invasive SCC that is completely excised with 3mm or less basement membrane invasion and 7mm or less horizontal spread.
How often does anal SCC spread?
32% nodal, 13% metastatic.
Workup of anal mass?
DRE/anoscopy/BIOPSY, FNA of lymphadenopathy, CT CAP for staging, MRI for locoregional disease
What is the Nigro protocol?
5-FU , mitomycin C, 30 Gray radiation x 3 weeks.
How successful is Nigro protocol?
80-90% for locoregional disease.
What chemotherapeutic do you consider to add to 5-FU for metastatic anal SCC?
Cisplatin.
When is surgery indicated for anal SCC?
Locoregional recurrence/persistence after Nigro protocol, after 6 months. Surgery of choice is salvage APR (5 yr overall survival 25-60% compared to 3%)
What is the surveillance after Nigro protocol?
DRE/anoscopy q3-6 months x 5 years; add panscan if nodal disease present or above T3 primary lesion.
How to treat T1 well-differentiated perianal SCC that you can pull out of anus easily ?
WLE 1 cm margins alone.
