Anus
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.[1]
Squamous metaplasia of the anus
Main article: Squamous metaplasia of the anus
Benign disease
Anal wart
- See condyloma acuminatum.
Pilonidal cyst
- Also pilonidal sinus and pilonidal disease.
Main article: Pilonidal cyst
Perianal abscess
General
- Common ditzel - often young men.[2]
- May be due to Crohn's disease.[3]
Microscopic
Features:
- Abscess - (extravascular) cluster of neutrophils - key feature.
- +/-Skin ulceration with reactive epithelium.
- +/-Reactive stromal cells.
DDx:
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PERIANAL TISSUE ("ABSCESS"), EXCISION:
- PERIANAL ABSCESS.
- REACTIVE SQUAMOUS EPITHELIUM WITH PARAKERTOSIS AND ULCERATION.
- ABUNDANT COCCI ORGANISMS IN CLUSTERS.
- NEGATIVE FOR MALIGNANCY.
PERIANAL TISSUE ("ABSCESS"), EXCISION:
- ABSCESS.
- SKIN WITH ULCERATION AND REACTIVE CHANGES.
- NEGATIVE FOR MALIGNANCY.
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.
Anal fistula
General
- Clinical diagnosis.
- May be seen in association with an abscess.
- Common in Crohn's disease.[4]
Microscopic
Features:
- Squamous mucosa with acute and chronic inflammation.
DDx:
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Submitted as "Perineal Fistula Tract", Excision:
- Consistent with fistula tract (acutely and chronically inflamed
squamous mucosa with underlying microabscess, skeletal muscle
and fibrosed tissue).
- NEGATIVE for dysplasia and NEGATIVE for malignancy.
Block letters
PERIANAL TISSUE ("OPENING OF FISTULA"), EXCISION:
- 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.
Hidradenoma papilliferum
- Can be perianal.[6]
Hemorrhoids
Main article: Hemorrhoid
Anal neoplasia
Immunosuppressed individuals and homosexuals have a higher risk of anal intraepithelial neoplasia (AIN) and anal cancer.[7][8]
Anal intraepithelial neoplasia
- Abbreviated AIN.
Main article: Anal intraepithelial lesions
Note:
- The terminology changing to match the one now widely used for the uterine cervix.
Anal cancer
- Anal squamous cell carcinoma - may be referred to as anal carcinoma - most common.
- Malignant melanoma.
- Adenocarcinoma from the rectum.
Anal squamous cell carcinoma
Main article: Anal squamous cell carcinoma
Anal gland adenocarcinoma
- Abbreviation AGA.
- AKA anal adenocarcinoma.
General
- Rare.
Risk factors:[9]
- Anal Crohn's disease.
- Chronic anal fistula.
- Anal sexual intercourse.
Microscopic
Features:[10]
- Adenocarcinoma within the anal wall but not within the mucosa, i.e. extramucosal and intramural - key feature.
- The tumour lies beneath the squamous mucosa/rectal mucosa.
DDx:
- Rectal adenocarcinoma - usu. CK7 -ve, CK20 +ve.
- Mucinous adenocarcinoma - usu. CK7 +ve, CK20 +ve.
Image:
IHC
Features:[10]
See also
References
- ↑ Bujanda, L.; Iriondo, C.; Muñoz, C.; Etxezarraga, C.; Ramírez, MM.; Ramos, F.; Sánchez, A. (Feb 2001). "Squamous metaplasia of the rectum and sigmoid colon.". Gastrointest Endosc 53 (2): 255-6. PMID 11174313.
- ↑ Ommer, A.; Herold, A.; Berg, E.; Fürst, A.; Sailer, M.; Schiedeck, T. (Jun 2012). "German S3 guideline: anal abscess.". Int J Colorectal Dis 27 (6): 831-7. doi:10.1007/s00384-012-1430-x. PMID 22362468.
- ↑ Lewis, RT.; Maron, DJ. (Sep 2010). "Efficacy and complications of surgery for Crohn's disease.". Gastroenterol Hepatol (N Y) 6 (9): 587-96. PMID 21088749.
- ↑ Burri, E.; Vavricka, SR. (Jul 2013). "[Perianal Crohn's disease].". Ther Umsch 70 (7): 417-28. doi:10.1024/0040-5930/a000427. PMID 23798025.
- ↑ Benjelloun, el B.; Abkari, M.; Ousadden, A.; Ait Taleb, K. (Jul 2013). "Squamous cell carcinoma associated anal fistulas in Crohn's disease unique case report with literature review.". J Crohns Colitis 7 (6): e232-5. doi:10.1016/j.crohns.2012.09.015. PMID 23069004.
- ↑ Daniel, F.; Mahmoudi, A.; de Parades, V.; Fléjou, JF.; Atienza, P. (Feb 2007). "An uncommon perianal nodule: hidradenoma papilliferum.". Gastroenterol Clin Biol 31 (2): 166-8. PMID 17347625.
- ↑ Park IU, Palefsky JM (March 2010). "Evaluation and Management of Anal Intraepithelial Neoplasia in HIV-Negative and HIV-Positive Men Who Have Sex with Men". Curr Infect Dis Rep 12 (2): 126–133. doi:10.1007/s11908-010-0090-7. PMC 2860554. PMID 20461117. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2860554/.
- ↑ Czoski-Murray C, Karnon J, Jones R, Smith K, Kinghorn G (November 2010). "Cost-effectiveness of screening high-risk HIV-positive men who have sex with men (MSM) and HIV-positive women for anal cancer". Health Technol Assess 14 (53): 1–131. doi:10.3310/hta14530. PMID 21083999.
- ↑ Tarazi, R.; Nelson, RL.. "Anal adenocarcinoma: a comprehensive review.". Semin Surg Oncol 10 (3): 235-40. PMID 8085101.
- ↑ 10.0 10.1 10.2 Warsch, S.; Bayraktar, UD.; Wen, BC.; Zeitouni, J.; Marchetti, F.; Rocha-Lima, CM.; Montero, AJ. (Mar 2012). "Successful treatment of anal gland adenocarcinoma with combined modality therapy.". Gastrointest Cancer Res 5 (2): 64-6. PMID 22690260.
- ↑ 11.0 11.1 Meriden, Z.; Montgomery, EA. (Feb 2012). "Anal duct carcinoma: a report of 5 cases.". Hum Pathol 43 (2): 216-20. doi:10.1016/j.humpath.2011.04.019. PMID 21820151.