Anus
The anus occasionally shows-up on the pathologists desk. It sometimes comes with the rectum and colon, as an abdominoperoneal resection (APR).
Benign disease
Anal wart
- See condyloma acuminatum.
Perianal abscess
General
- Common - often young men.[1]
- May be due to Crohn's disease.[2]
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.[3]
Microscopic
Features:
- Squamous mucosa with acute and chronic inflammation.
DDx:
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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.[5]
Hemorrhoids
General
- Benign.
Clinical features:[6]
- Bright red blood per rectum (BRBPR).
- Pain.
- Itching.
- Prolapse.
Gross
Features:[7]
- Grey mucosa.
- Pale or purple stroma.
Microscopic
Features:[7]
- Polypoid lesion - epithelium on three sides:
- Large dilated veins and thick-walled vessels +/- fibrin thrombi - key feature.
- Edema.
- Squamous epithelium +/- keratinization or columnar epithelium.
DDx:
- Fibroepithelial polyp.
- Vascular lesions.
- Kaposi sarcoma.
- Angiosarcoma.
- Arteriovenous malformation - has large arteries.
Image:
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ANAL LESION, REMOVAL: - HEMORRHOID.
HEMORRHOIDS, EXCISION: - HEMORRHOIDS.
Micro
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.
Anal mucosa only
The sections show anal mucosa, and submucosa with prominent blood vessels in a fibrotic stroma. The anal mucosa is unremarkable.
Anal neoplasia
Immunosuppressed individuals and homosexuals have a higher risk of anal intraepithelial neoplasia (AIN) and anal cancer.[8][9]
Anal intraepithelial neoplasia
- Abbreviated AIN.
General
- Precursor lesion of anal squamous cell carcinoma.
- Usually HPV associated.
- May be prevented by HPV vaccine.
Grading
AIN is graded much like cervical intraepithelial neoplasia:
- High-grade anal intraepithelial neoplasia (HGAIN).
- Low-grade anal intraepithelial neoplasia (LGAIN).
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ANAL CANAL, RIGHT UPPER QUADRANT, BIOPSY: - LOW-GRADE SQUAMOUS INTRAEPITHELIAL LESION (CONDYLOMA ACUMINATUM-LIKE).
ANAL CANAL, LEFT UPPER QUADRANT, BIOPSY: - LOW-GRADE SQUAMOUS INTRAEPITHELIAL LESION. - RECTAL MUCOSA WITHIN NORMAL LIMITS.
SKIN LESION, PERIANAL, BIOPSY: - ANAL INTRAEPITHELIAL NEOPLASIA 3 (SEVERE DYSPLASIA), WARTY-TYPE. - MARGIN POSITIVE FOR ANAL INTRAEPITHELIAL NEOPLASIA 3.
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 squamous cell carcinoma - may be referred to as anal carcinoma - most common.
- Malignant melanoma.
- Adenocarcinoma from the rectum.
Anal squamous cell carcinoma
General
- Most common form of anal cancer.
Risk factors:[10]
- Men who have sex with men.
- Immunosuppressed.
- HIV infection.
Microscopic
Features:
DDx:
- Anal gland adenocarcinoma.
- Poorly differentiated rectal adenocarcinoma.
IHC
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RECTUM, DISTAL, BIOPSY: - INVASIVE SQUAMOUS CELL CARCINOMA.
Anal gland adenocarcinoma
- Abbreviation AGA.
- AKA anal adenocarcinoma.
General
- Rare.
Risk factors:[12]
- Anal Crohn's disease.
- Chronic anal fistula.
- Anal sexual intercourse.
Microscopic
Features:[13]
- 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:[13]
See also
References
- ↑ 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.
- ↑ Cazemier, M.; Felt-Bersma, RJ.; Cuesta, MA.; Mulder, CJ. (Jan 2007). "Elastic band ligation of hemorrhoids: flexible gastroscope or rigid proctoscope?". World J Gastroenterol 13 (4): 585-7. PMID 17278225.
- ↑ 7.0 7.1 Iacobuzio-Donahue, Christine A.; Montgomery, Elizabeth A. (2005). Gastrointestinal and Liver Pathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 401. ISBN 978-0443066573.
- ↑ 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.
- ↑ Kutlubay, Z.; Engin, B.; Zara, T.; Tüzün, Y.. "Anogenital malignancies and premalignancies: Facts and controversies.". Clin Dermatol 31 (4): 362-73. doi:10.1016/j.clindermatol.2013.01.003. PMID 23806153.
- ↑ 11.0 11.1 Gunia, S.; Koch, S.; May, M. (Feb 2013). "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?". J Clin Pathol 66 (2): 109-12. doi:10.1136/jclinpath-2012-201138. PMID 23105122.
- ↑ Tarazi, R.; Nelson, RL.. "Anal adenocarcinoma: a comprehensive review.". Semin Surg Oncol 10 (3): 235-40. PMID 8085101.
- ↑ 13.0 13.1 13.2 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.
- ↑ 14.0 14.1 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.