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==
===General===
===General===
*Common.
*Common [[ditzel]] - often young men.<ref name=pmid22362468>{{Cite journal  | last1 = Ommer | first1 = A. | last2 = Herold | first2 = A. | last3 = Berg | first3 = E. | last4 = Fürst | first4 = A. | last5 = Sailer | first5 = M. | last6 = Schiedeck | first6 = T. | title = German S3 guideline: anal abscess. | journal = Int J Colorectal Dis | volume = 27 | issue = 6 | pages = 831-7 | month = Jun | year = 2012 | doi = 10.1007/s00384-012-1430-x | PMID = 22362468 }}</ref>
*May be due to [[Crohn's disease]].<ref name=pmid21088749>{{Cite journal  | last1 = Lewis | first1 = RT. | last2 = Maron | first2 = DJ. | title = Efficacy and complications of surgery for Crohn's disease. | journal = Gastroenterol Hepatol (N Y) | volume = 6 | issue = 9 | pages = 587-96 | month = Sep | year = 2010 | doi =  | PMID = 21088749 }}</ref>


===Microscopic===
===Microscopic===
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===Sign out===
===Sign out===
<pre>
<pre>
PERIANAL MASS, EXCISION:  
PERIANAL TISSUE ("ABSCESS"), EXCISION:
- PERIANAL ABSCESS.  
- PERIANAL ABSCESS.
- REACTIVE SQUAMOUS EPITHELIUM WITH PARAKERTOSIS AND ULCERATION.  
- REACTIVE SQUAMOUS EPITHELIUM WITH PARAKERTOSIS AND ULCERATION.
- ABUNDANT COCCI ORGANISMS IN CLUSTERS.  
- ABUNDANT COCCI ORGANISMS IN CLUSTERS.
- NEGATIVE FOR MALIGNANCY.
- NEGATIVE FOR MALIGNANCY.
</pre>
</pre>


==Hidradenoma papilliferum==
<pre>
:See ''[[Hidradenoma papilliferum]]''.
PERIANAL TISSUE ("ABSCESS"), EXCISION:
*Can be perianal.<ref name=pmid17347625>{{Cite journal  | last1 = Daniel | first1 = F. | last2 = Mahmoudi | first2 = A. | last3 = de Parades | first3 = V. | last4 = Fléjou | first4 = JF. | last5 = Atienza | first5 = P. | title = An uncommon perianal nodule: hidradenoma papilliferum. | journal = Gastroenterol Clin Biol | volume = 31 | issue = 2 | pages = 166-8 | month = Feb | year = 2007 | doi =  | PMID = 17347625 }}</ref>
- ABSCESS.
- SKIN WITH ULCERATION AND REACTIVE CHANGES.
- NEGATIVE FOR MALIGNANCY.
</pre>
 
====Micro====
The sections show skin with acanthosis, hypergranulosis, compact hyperkeratosis and focal full thickness loss of the epidermis, associated with a mixed inflammatory infiltrate. The dermis has reactive fibroblasts with moderate grey cytoplasm, nuclear enlargement and round small nucleoli. The fibroblast nuclei have regular nuclear membranes and a bland chromatin pattern. Clusters of neutrophils are present. There is no epidermal nuclear atypia. Mitotic activity is seen focally. No atypical mitotic figures are apparent. The inflammation extends to the deep aspect of the specimen.


==Hemorrhoids==
==Anal fistula==
===General===
===General===
*Benign.
*[[Clinical diagnosis]].
 
*May be seen in association with an [[perianal abscess|abscess]].
Clinical features:<ref>{{Cite journal  | last1 = Cazemier | first1 = M. | last2 = Felt-Bersma | first2 = RJ. | last3 = Cuesta | first3 = MA. | last4 = Mulder | first4 = CJ. | title = Elastic band ligation of hemorrhoids: flexible gastroscope or rigid proctoscope? | journal = World J Gastroenterol | volume = 13 | issue = 4 | pages = 585-7 | month = Jan | year = 2007 | doi = | PMID = 17278225 }}</ref>
*Common in Crohn's disease.<ref name=pmid23798025>{{Cite journal  | last1 = Burri | first1 = E. | last2 = Vavricka | first2 = SR. | title = [Perianal Crohn's disease]. | journal = Ther Umsch | volume = 70 | issue = 7 | pages = 417-28 | month = Jul | year = 2013 | doi = 10.1024/0040-5930/a000427 | PMID = 23798025 }}</ref>
*Bright red blood per rectum (BRBPR).
*Pain.
*Itching.
*Prolapse.
 
===Gross===
Features:<ref name=Ref_GLP401>{{Ref GLP|401}}</ref>
*Grey mucosa.
*Pale or purple stroma.


===Microscopic===
===Microscopic===
Features:<ref name=Ref_GLP401>{{Ref GLP|401}}</ref>
Features:
*Polypoid lesion - epithelium on three sides:
*Squamous mucosa with acute and chronic inflammation.
**Large dilated veins and thick-walled vessels +/- fibrin thrombi - '''key feature'''.
**Edema.
**Squamous epithelium +/- keratinization ''or'' columnar epithelium.


DDx:
DDx:
*[[Fibroepithelial polyp]].
*[[Squamous cell carcinoma]].<ref name=pmid23069004>{{Cite journal  | last1 = Benjelloun | first1 = el B. | last2 = Abkari | first2 = M. | last3 = Ousadden | first3 = A. | last4 = Ait Taleb | first4 = K. | title = Squamous cell carcinoma associated anal fistulas in Crohn's disease unique case report with literature review. | journal = J Crohns Colitis | volume = 7 | issue = 6 | pages = e232-5 | month = Jul | year = 2013 | doi = 10.1016/j.crohns.2012.09.015 | PMID = 23069004 }}</ref>
*Vascular lesions.
**[[Kaposi sarcoma]].
**[[Angiosarcoma]].
**[[Arteriovenous malformation]] - has large arteries.
 
Image:
*[http://www.profimedia.si/picture/longitudinal-section-of-human-rectum-hemorrhoid-tissue/0039860546/ Hemorrhoids (profimedia.si)].


===Sign out===
===Sign out===
<pre>
<pre>
ANAL LESION, REMOVAL:
PERIANAL TISSUE ("OPENING OF FISTULA"), EXCISION:
- HEMORRHOID.
- PERIANAL TISSUE CONSISTING OF SCANT SQUAMOUS EPITHELIUM AND MUSCLE
  WITH MILD INFLAMMATION.
- SMALL COLLECTION OF NEUTROPHILS.
- MILD FIBROSIS WITH FOCALLY PROMINENT DILATED BLOOD VESSELS.
- NEGATIVE FOR DYSPLASIA AND NEGATIVE FOR MALIGNANCY.
</pre>
</pre>


<pre>
==Hidradenoma papilliferum==
HEMORRHOIDS, EXCISION:  
:See ''[[Hidradenoma papilliferum]]''.
- HEMORRHOIDS.
*Can be perianal.<ref name=pmid17347625>{{Cite journal  | last1 = Daniel | first1 = F. | last2 = Mahmoudi | first2 = A. | last3 = de Parades | first3 = V. | last4 = Fléjou | first4 = JF. | last5 = Atienza | first5 = P. | title = An uncommon perianal nodule: hidradenoma papilliferum. | journal = Gastroenterol Clin Biol | volume = 31 | issue = 2 | pages = 166-8 | month = Feb | year = 2007 | doi =  | PMID = 17347625 }}</ref>
</pre>


====Micro====
==Hemorrhoids==
The sections show rectal and anal mucosa, and a submucosa with prominent blood vessels in a fibrotic stroma.  The rectal mucosa has focal reactive nuclear changes and evidence of prior erosions. The anal mucosa is unremarkable.
{{Main|Hemorrhoid}}


=Anal neoplasia=
=Anal neoplasia=
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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===
Note:
AIN is graded much like [[cervix|cervical intraepithelial neoplasia]]:
*The terminology changing to match the one now widely used for the [[uterine cervix]].
*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>
SKIN LESION, PERIANAL, BIOPSY:
- 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]]''.
 
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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DDx:
DDx:
*[[Rectal adenocarcinoma]] - usu. CK7 -ve, CK20 +ve.
*[[Rectal adenocarcinoma]] - usu. CK7 -ve, CK20 +ve.
*Mucinous adenocarcinoma - usu. CK7 +ve, CK20 +ve.
*[[Mucinous adenocarcinoma]] - usu. CK7 +ve, CK20 +ve.


Image:
Image:
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