Anal intraepithelial neoplasia: A review of diagnosis and management

Table 1 Unification of terms relating to anal intraepithelial neoplasia

Normal	LSIL		HSIL
	Condyloma or ASCUS	AIN grade I	AIN grade II	AIN grade III
	Mild dysplasia		Moderate dysplasia	Severe dysplasia

ASCUS: Atypical squamous cells of undetermined significance; LSIL: Low-grade squamous intraepithelial lesion; HSIL: High-grade squamous intraepithelial lesion; AIN: Anal intraepithelial neoplasia.

Table 2 Rates of anal cancer among various populations compiled from various sources

Anal cancer rates among select populations, per 100000 person-years
General population	2[1]
General population, female	0.55-2.4[13]
HIV positive women	3.9-30[13]
HIV negative MSM	5.1[12]
Solid organ transplant	10-15[66]
Prior HPV related malignancy	0.8-63.8[13]
HIV positive MSM	49.5[12]
Colon cancer in general population	41[2]

HIV: Human immunodeficiency virus; MSM: Sex with men; HPV: Human papilloma virus.

Table 3 Progression rates of anal intraepithelial neoplasia to squamous cell carcinoma

Progression	No. patients	Rate of progression	Median or average progression time	Ref.
AIN II/III to SCC	72	11%	42 mo	[33]
AIN III to SCC	35	8.6%	53 mo	[34]
AIN I to AIN III	199	12.6% (8.1/100 person-years)	18 mo	[35]
ASCUS/AIN I to AIN II/III	556	24.5% (10.5/100 person-years)	36 mo	[36]
HSIL to SCC	138	19.6%	57 mo. w/prevalent HSIL; 64 mo. w/incident HSIL	[37]

ASCUS: Atypical squamous cells of undetermined significance; LSIL: Low-grade squamous intraepithelial lesion; HSIL: High-grade squamous intraepithelial lesion; AIN: Anal intraepithelial neoplasia; SCC: Squamous cell carcinoma.