1. Anus Anatomic subsites of the anus. The epithelium in the peri-anal region and the vulvar zone is at risk for squamous carcinomas, along with HPV and other skin infections. While these are of a lower malignant potential, they can be troublesome. In women, there are diseases that give rise to peri-vulvar squamous carcinoma that can be a problem. In men, there may be condylomas in HIV positive disease, and perhaps some HPV positive disease that can morph into squamous cell carcinoma. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

2. Anus Regional lymph nodes of the anus. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

3. Anus T1 is defined as tumor that is 2 cm or less in greatest dimension. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

4. Anus Two views of T2 showing tumor that is more than 2 cm but not more than 5 cm in greatest dimension. On the right side of the diagram, the tumor extends above the dentate line. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

5. Anus T3 is defined as tumor that is more than 5 cm in greatest dimension. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

6. Anus T4 is defined as tumor of any size that invades adjacent organ(s), e.g., vagina (as illustrated), urethra, and bladder. Note: Direct invasion of the rectal wall, perirectal skin, subcutaneous tissue, or the sphincter muscle(s) is not classified as T4. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

7. Anus N1 is defined as metastasis in perirectal lymph node(s). Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

8. Anus N2 is defined as metastasis in unilateral internal iliac. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

9. Anus N2 is defined as metastasis in inguinal lymph node(s). Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

10. Anus N2 is defined as metastases in unilateral internal iliac and inguinal lymph node(s). Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

11. Anus N3 is defined as metastasis in perirectal and inguinal lymph nodes (as illustrated) and/or bilateral internal iliac and/or inguinal lymph nodes. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

12. Anus N3 is defined as metastases in bilateral internal iliac lymph nodes. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer

13. Anus N3 is defined as metastases in bilateral internal iliac and inguinal lymph nodes. Compton, C.C., Byrd, D.R., et al., Editors. AJCC CancerStaging Atlas, 2nd Edition. New York: Springer, 2012. ©American Joint Committee on Cancer