• 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
• No known risk factors.
• Risk factors for cutaneous melanoma like
nevus, sunlight exposure does not predispose
to anal melanoma.
• 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.
• Bleeding per rectum –
most common (50-
• Perianal itching and
• mass protruding through
• perianal discharge.
• More common in women
• Mean age :70 yrs(29-91)
• Distant metastasis seen in 30% of people at
● USG abdomen/pelvis : to r/o liver mets.
● ENDOLUMINAL USG : Depth of invasion
and nodal status.
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%.
Melanoma panel of markers
To R/o other disease
*Cytokeratins (Paget’s disease), CD45 (lymphoma),
chromogranin and synaptophysin (undifferen-
tiated carcinoma), CD34 (GIST) and Desmin and
• The staging of anal melanoma differs from that of
cutaneous melanoma( based on Breslow
• 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.
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
• WIDE LOCAL EXCISION / ABDOMINO PERINEAL
RESECTION for Stage I/II disease
• Wide local excision (R0 resection ) is
WIDE LOCAL EXCISION
• Loan star retractor preferred.
• 1 cm margin(R0 resection) .
• TEMS for localised leision in rectum
• 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
• Droesh et al -2005
• 301 pt
• 172-APR,129- WLE.
• Mean survival same for both.
• 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.
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 )
• Systemic chemotherapy
• Drugs used are akin to cutaneous melanoma
• Commonly used drugs
• 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.
• STAGE I &II : mean survival 11 – 20 months.
• STAGE III : Less than 10 months.
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
• 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