1. The Pathology of Anal Neoplasia Dr Bryan F Warren Consultant Gastrointestinal Pathologist, Honorary Senior Lecturer and Fellow of Linacre College, Oxford M62 Course 2005

3. Epithelial tumours of the anus Rare and diverse in histological type. many different types of epithelium present. malignant tumours anal canal and anal margin. Anal margin tumours-keratinising squamous cell carcinomas with better prognosis and need less aggressive treatment than their non- keratinising variants in the anal canal.

4. fibro epithelial polyps, inflammatory cloacogenic polyps squamous hyperplasia (leucoplakia). Anal intraepithelial neoplasia (AIN). Benign tumours of the anus

5. AIN (Dysplasia of the squamous epithelium of the anal canal) AIN 1, 2 or 3 depending on its severity precursor of squamous cell carcinoma related to human papilloma virus. Interobserver variation in the diagnosis of AIN 1, 2 and 3. 44.6 44.7 44.8 44.9 44.10. AIN 1 and wart virus effects AIN 111

6. Viral warts Viral warts may also be seen at the anal verge - condylomata acuminata Giant condyloma of Buschke and Loewenstein which may be enormous before it develops invasion. The invasion is by veruccous carcinoma which may present considerable difficulties in diagnosis on biopsy, since the cytology is so bland.

7. Benign anal lesions which may mimic malignancy. Keratoacanthoma - benign lesion which can be misdiagnosed as SCC Bowen’s Disease - SCC in situ. Cf… Bowenoid papulosis is a papular eruption in the anogenital region in young to middle aged adults and the histology resembles Bowen’s Disease. This can cause considerable confusion if viewed histologically in isolation without the history and knowledge of the macroscopic appearances of this eruption around the anus and this may lead to misdiagnosis with serious consequences.

8. Sweat gland tumours, Extramammary Paget’s disease, (Metastatic tumours occasionally) Uncommon tumours

9. Malignant epithelial tumours squamous cell carcinoma, which in the anal canal is often basaloid or non-keratinising, malignant melanoma, which unfortunately usually presents quite late due to the site Anal gland tumours

10. Malignant melanoma, unfortunately usually presents quite late due to the site Malignant melanoma

11. Adenocarcinoma of anal ducts and anal glands. colloid carcinoma causes considerable difficulties biopsies - mucus only (endoscopic appearances are characteristic). Mucinous adenocarcinomas may occur within fistulae. Anal gland adenocarcinoma

13. Anal margin squamous cell carcinomas and basal cell carcinomas may be seen other very rare tumours may occur occasionally Anal margin tumours - skin tumours

14. Pathological staging of anal canal carcinoma Tx cannot be assessed T0 no evidence of primary tumour Tis carcinoma in situ T1Tumour =/< 2 cm T2 Tumour = 2-5cm T3 Tumour > 5cm T4 Tumour invades adjacent organs (vagina, urethra, bladder - invasion of sphincter muscle(s) alone does not make it T4)

16. Pathological staging of anal canal carcinoma Regional lymph nodes: perirectal, internal iliac, inguinal lymph nodes. Nx cannot be assessed N0 No regional lymph node metastasis N1 Metastasis in perirectal lymph nodes N2 Metastasis in unilateral internal iliac and / or inguinal lymph node(s) N3 Metastasis in perirectal and inguinal lymph nodes and / or bilateral internal iliac and / or inguinal lymph nodes

17. Pathological staging of anal canal carcinoma Mx,M0,M1 UICC stages Stage 0 Tis N0M0 Stage I T1 N0M0 Stage II T2/3 N0M0 Stage IIIA T1,2,3 N1M0 or T4N0M0 Stage IIIB T4N1M0, or any T withN2,N3M0 Stage IV Any TorN with M1

18. Summary Correct pathological diagnosis of anal neoplasia is crucial to the correct management.