Anus and perianal area
Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 16 April 2013, last major update April 2005
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.
● Tumors that arise from downward extension of rectal tumors or from columnar epithelium of proximal zone are considered rectal tumors, are usually CK7-/CK20+
(Arch Pathol Lab Med 2001;125:1074)
● Rare from anal canal; may arise from anal glands or from congenital anorectal duplications, usually in older patients
● May present with fistulous tracts or as vaginal cysts
● Often long history of perianal fistulas, abscesses, surgery
● Indolent course with gradual progression
● HPV 18 is present in 2/ 6; 0/6 were HPV 16+ (Mod Pathol 1991;4:58)
● May contain melanin pigment, perhaps due to tumor cell phagocytosis of melanin from melanocytes (Am J Surg Pathol 1981;5:711)
● May be large, ulcerated buttock masses with gelatinous consistency
● Mucin producing epithelium
● Often well differentiated resembling trapped glands
● May have dilated, mucin-filled cysts containing free floating tumor cells (colloid adenocarcinoma), granulomatous reaction to mucin
● Rectal mucosa not involved
End of Anus and perianal area > Carcinoma > Adenocarcinoma
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