Difference between revisions of "Anus"

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The '''anus''' occasionally shows-up on the pathologists desk.  It sometimes comes with the rectum and [[colon]], as an abdominoperoneal resection (APR).
The '''anus''' occasionally shows-up on the pathologists desk.  It sometimes comes with the rectum and [[colon]], as an abdominoperoneal resection (APR).
=Normal=
*The dentate line (also known as the ''pectinate line'') divides the anal canal into upper two thirds and lower one third.
*Typically, the squamocolumnar junction is just above the dentate line.
Note:
*Squamous epithelium 1 cm proximal to the dentate line is considered abnormal.<ref name=pmid11174313>{{Cite journal  | last1 = Bujanda | first1 = L. | last2 = Iriondo | first2 = C. | last3 = Muñoz | first3 = C. | last4 = Etxezarraga | first4 = C. | last5 = Ramírez | first5 = MM. | last6 = Ramos | first6 = F. | last7 = Sánchez | first7 = A. | title = Squamous metaplasia of the rectum and sigmoid colon. | journal = Gastrointest Endosc | volume = 53 | issue = 2 | pages = 255-6 | month = Feb | year = 2001 | doi =  | PMID = 11174313 }}</ref>
==Squamous metaplasia of the anus==
{{Main|Squamous metaplasia of the anus}}


=Benign disease=
=Benign disease=
==Anal wart==
==Anal wart==
*See ''[[condyloma acuminatum]]''.
*See ''[[condyloma acuminatum]]''.
==Pilonidal cyst==
:Also ''pilonidal sinus'' and ''pilonidal disease''.
{{Main|Pilonidal cyst}}


==Perianal abscess==
==Perianal abscess==
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==Anal intraepithelial neoplasia==
==Anal intraepithelial neoplasia==
*Abbreviated ''AIN''.
*Abbreviated ''AIN''.
===General===
{{Main|Anal intraepithelial lesions}}
*Precursor lesion of anal [[squamous cell carcinoma]].
*Usually [[HPV]] associated.
**May be prevented by HPV vaccine.
 
===Grading===
AIN is graded much like [[cervix|cervical intraepithelial neoplasia]]:
*High-grade anal intraepithelial neoplasia (HGAIN).
*Low-grade anal intraepithelial neoplasia (LGAIN).
 
===Sign out===
<pre>
ANAL CANAL, RIGHT UPPER QUADRANT, BIOPSY:
- LOW-GRADE SQUAMOUS INTRAEPITHELIAL LESION (CONDYLOMA ACUMINATUM-LIKE).
</pre>
 
<pre>
ANAL CANAL, LEFT UPPER QUADRANT, BIOPSY:
- LOW-GRADE SQUAMOUS INTRAEPITHELIAL LESION.
- RECTAL MUCOSA WITHIN NORMAL LIMITS.
</pre>


<pre>
Note:
SKIN LESION, PERIANAL, BIOPSY:  
*The terminology changing to match the one now widely used for the [[uterine cervix]].
- ANAL INTRAEPITHELIAL NEOPLASIA 3 (SEVERE DYSPLASIA), WARTY-TYPE.
- MARGIN POSITIVE FOR ANAL INTRAEPITHELIAL NEOPLASIA 3.
</pre>
 
====Micro====
There is dysplastic squamous epithelium with coarse chromatin, nuclear hyperchromasia,
nuclear enlargement, irregular nuclear membranes, and an increase nuclear-to-cytoplasmic
ratio.  Mitotic activity is abundant. Several atypical mitoses are identified.
 
The dysplastic squamous epithelium shows minimal maturation toward the surface (AIN 3). A
sizable portion of the lesion show some maturation to the surface (AIN 2).
 
Inflammation at the dermal-epidermal interface is minimal and the dermal-epidermal
interface is well-demarcated.  Focal ulceration is present.
 
The margin of the biopsy has severely dysplastic epithelium (AIN 3).


=Anal cancer=
=Anal cancer=
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*[[AKA]] ''anal squamous carcinoma''.
*[[AKA]] ''anal squamous carcinoma''.
*[[AKA]] ''squamous cell carcinoma of the anus''.
*[[AKA]] ''squamous cell carcinoma of the anus''.
===General===
{{Main|Anal squamous cell carcinoma}}
*Most common form of anal cancer.
 
Risk factors:<ref name=pmid23806153>{{Cite journal  | last1 = Kutlubay | first1 = Z. | last2 = Engin | first2 = B. | last3 = Zara | first3 = T. | last4 = Tüzün | first4 = Y. | title = Anogenital malignancies and premalignancies: Facts and controversies. | journal = Clin Dermatol | volume = 31 | issue = 4 | pages = 362-73 | month =  | year =  | doi = 10.1016/j.clindermatol.2013.01.003 | PMID = 23806153 }}</ref>
*Men who have sex with men.
*Immunosuppressed.
*[[HIV]] infection.
===Microscopic===
Features:
*See ''[[squamous cell carcinoma]]''.
 
<gallery>
Image:Anus SquamousCellCarcinoma SCC NonKeratinizing AIA SCCIS CTR.jpg|Anus Squamous Cell Carcinoma (Non Keratinizing) - (SKB)
Image:Anus SquamousCellCarcinoma SCC NonKeratinizing MP CTR.jpg|Anus Squamous Cell Carcinoma (Non Keratinizing) - (SKB)
Image:Anus SquamousCellCarcinoma SCC NonKeratinizing MP4 CTR.jpg|Anus Squamous Cell Carcinoma (Non Keratinizing or shall we say poorly keratinizing as there are squamatized nests focally at high power) - (SKB)
</gallery>
DDx:
*[[Anal gland adenocarcinoma]].
*Poorly differentiated [[rectal adenocarcinoma]].
 
===IHC===
*p16 +ve.<ref name=pmid23105122/>
*CDX2 -ve/+ve.
**May be useful to differentiate from vulva and penis.<ref name=pmid23105122>{{Cite journal  | last1 = Gunia | first1 = S. | last2 = Koch | first2 = S. | last3 = May | first3 = M. | title = Is CDX2 immunostaining useful for delineating anorectal from penile/vulvar squamous cancer in the setting of squamous cell carcinoma with clinically unknown primary site presenting with histologically confirmed inguinal lymph node metastasis? | journal = J Clin Pathol | volume = 66 | issue = 2 | pages = 109-12 | month = Feb | year = 2013 | doi = 10.1136/jclinpath-2012-201138 | PMID = 23105122 }}</ref>
 
===Sign out===
<pre>
RECTUM, DISTAL, BIOPSY:
- INVASIVE SQUAMOUS CELL CARCINOMA.
</pre>


==Anal gland adenocarcinoma==
==Anal gland adenocarcinoma==
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