- Anal melanoma is a rare and aggressive form of melanoma, accounting for 0.5-2% of anal malignancies. It commonly presents with bleeding per rectum in patients around age 70. - Diagnosis involves visual inspection, biopsy, and immunohistochemistry confirming S100 and HMB45 markers. Surgery with wide local excision is the primary treatment for stage I-II disease. - Prognosis is poor with average survival of 11-20 months for early stage and less than 10 months for stage III metastatic disease. Targeted therapies for common mutations show promise but survival has only improved by 3-5 months.

1. MELANOMA-ANAL CANAL
Dr.A.Joseph Stalin Mch PG
PROF.DR.R.RAJARAMAN’S UNIT
DEPT OF SURGICAL ONCOLOGY
GOVT ROYAPETTAH HOSPITAL
CHENNAI

2. CONTENTS
• Anal Mucosal Melanoma
- Introduction
- Clinical presentation
- Diagnosis
- Treatment
.Take home message

3. INTRODUCTION
• Anal melanoma - 0.5 to 2% - anal malignancies
• Less than 2% of all melanomas.
• The third most common melanoma after the
cutaneous and ocular varieties.
• Most common site for primary gastrointestinal
melanoma.

4. ETIOLOGY
• No known risk factors.
• Risk factors for cutaneous melanoma like
nevus, sunlight exposure does not predispose
to anal melanoma.

5. PATHOLOGY
• Melanoma arises from melanocytes derived
from neural crest cells.
• Melanocytes subjected to carcinogenic stimuli
undergo malignant transformation.
• Carcinogenic stimuli in anal melanoma unknown
• Subsets of anal melanoma shows mutation in
BRAF, Ckit , p53 mutation.

6. Symptoms
• Bleeding per rectum –
most common (50-
60%)
• Perianal itching and
irritation (15-20%)
• mass protruding through
anus.
• perianal discharge.

7. CLINICAL PRESENTATION
• More common in women
• Mean age :70 yrs(29-91)
• Distant metastasis seen in 30% of people at
diagnosis

8. SPREAD
• Lymphatic Spread : Inguinal & mesorectal
nodes.
• Systemic : Lung,Liver,Brain , Bone

9. DIAGNOSIS
• Diagnosis can be made with visual inspection and
anoscopy.
• commonly present as polypoidal mass
• Distance from anal verge and mobility assessed

10. • Clinically evident pigmented leision only in
20 % of cases.In others pigmentation is
obscured.
• 20 % are amelanotic histologically.

11. THROMBOSED PILE LIKE MASSS

12. Polypoidal lesion in colonoscopy

13. DIFFERENTIAL DIAGNOSIS
●Anal carcinoma/lymphoma
●Perianal haematoma
●Thrombosed haemorrhoids
●Anal or Rectal Polyp

14. INVESTIGATIONS
• PROCTOSCOPY & BIOPSY
• USG ABDOMEN/PELVIS
• ENDOLUMINAL USG
• PET ?

15. ● USG abdomen/pelvis : to r/o liver mets.
● ENDOLUMINAL USG : Depth of invasion
and nodal status.

16. ROLE OF PET CT
• Positron emission tomography (PET) may be
helpful for staging of anorectal melanoma.
• The sensitivity was 74 to 100% and specificity
67 to 100%.

17. IMMUNOHISTOCHEMISTRY
Melanoma panel of markers
S-100 protein
Vimentin,
Melan-A,
HMB-45.
To R/o other disease
*Cytokeratins (Paget’s disease), CD45 (lymphoma),
chromogranin and synaptophysin (undifferen-
tiated carcinoma), CD34 (GIST) and Desmin and
caldesmon (sarcoma)

18. STAGING
• The staging of anal melanoma differs from that of
cutaneous melanoma( based on Breslow
classification).
• Anal melanoma is staged on a clinical basis, focusing on
locoregional and distant spread.
( Clinics of Colorectal surgery vol19 Ross etal )
• Stage I is local disease.
• stage II is local disease with regional lymph nodes.
• stage III is distant metastatic disease.

19. STAGE I & II
• Surgical excision is the treatment of choice.
• Melanoma is highly resistant to RT/ Chemo.
No role either as defnitive treatment or as
adjuvant therapy.

20. SURGERY
• WIDE LOCAL EXCISION / ABDOMINO PERINEAL
RESECTION for Stage I/II disease
• Wide local excision (R0 resection ) is
preferred.

21. WIDE LOCAL EXCISION
• Loan star retractor preferred.
• 1 cm margin(R0 resection) .
• TEMS for localised leision in rectum

22. APR
• When anal sphinter is involved or R0
resection mandates sphinter excision, APR
indicated in stage I& II.
• No survival advantage for APR when
compared to wide local excision

23. STUDIES
• Droesh et al -2005
• 301 pt
• 172-APR,129- WLE.
• Mean survival same for both.

24. • A comparison of wide local excision with
abdominoperineal resection in anorectal melanoma.
• Yap LB1, Neary P.
• Seventeen large case series from over the past 10
years were reviewed.
• Comparison of the survival of patients who underwent
APR with those who underwent WLE showed no
statistically significant advantage for either procedure
in patients at all disease stages.
• APR should therefore only be performed when local
excision is not possible or for palliative purposes.

25. Role of lymph node dissection
• Lymph node dissection – inguinal/mesorectal-
does not confer survival advantage although it
improves locoregional control.
• Bollo et al(23 patients )
• Moozar et al (14 patients )
• Brady et al(retrospective analysis )

26. STAGE III
• Systemic chemotherapy
• Drugs used are akin to cutaneous melanoma
• Commonly used drugs
Dacarbazine
Temozolamide

27. TARGETED THERAPY
• cKIT/ BRAF mutation seen in some subgroup
• Targeted therapy –cKIT ( Imatinib)/ BRAF
(Verufunamib) in adjuvant and metastatic
setting shows good response in phase II trial.
• Yeh et al .Interim analysis shows median
survival improves by 3-5 months.

28. PROGNOSTIC FACTORS
• Tumour thickness.
• Ulceration
• Mitotic rate
• Nodal involvement.
• Relation to dentate line.

29. PROGNOSIS
• STAGE I &II : mean survival 11 – 20 months.
• STAGE III : Less than 10 months.

30. TAKE HOME MESSAGE
• Anal melanoma is a rare and aggressive
variant of mucosal melanoma
• Often misdiagnosed as benign leision.
• High index of suspicion is needed.
• Immunohistochemistry is the gold standard
for diagnosis.

31. • Surgery is the treatment of choice for stage
I& II .
• Wide local excision is the preferred surgery.
• Role of targeted therapy is emerging.
• Mean survival is only 20 months

32. THANK U