Anus

Question 1

Squamous Cell Carcinoma

Answer 1

• Most common malignancy on anal tract
• Strong association with HPV

Risk Factors:
* Men who have sex with men
* Immunosuppresed
* HIV infection

Site:
* Above dentate line –> women, 60s
* Below dentate line –> men, 30s

IHC:
* Squamous markers –> p40, CK5/6
* HPV staining –> p16

Etiologic Subtypes:

• HPV neg, p53 aberrant staining –> worse prognosis
• HPV neg, P53 wild type –> intermediate prognosis
• HPV pos, p53 aberrant staining –> Intermediate prognosis
• HPV pos, p53 wild type –> Best prognosis

Question 2

Perianal Gland AdenoCa

Answer 2

• Rare adenoCa
• NOT rectal adenoCa that has spread
• May arise from anal glands –> from congenital anorectal duplications along a fistula tract

Molecular:
* KRAS mutations –> 47%
* NRAS mutations –> 6%

IHC:
* CK7 +
* CK 20 -

(compared to CRC which are CK7-, CK20+)