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Melanoma anal canal

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ANAL CANAL MELANOMA

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Melanoma anal canal

  1. 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. 2. CONTENTS • Anal Mucosal Melanoma - Introduction - Clinical presentation - Diagnosis - Treatment .Take home message
  3. 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. 4. ETIOLOGY • No known risk factors. • Risk factors for cutaneous melanoma like nevus, sunlight exposure does not predispose to anal melanoma.
  5. 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. 6. Symptoms • Bleeding per rectum – most common (50- 60%) • Perianal itching and irritation (15-20%) • mass protruding through anus. • perianal discharge.
  7. 7. CLINICAL PRESENTATION • More common in women • Mean age :70 yrs(29-91) • Distant metastasis seen in 30% of people at diagnosis
  8. 8. SPREAD • Lymphatic Spread : Inguinal & mesorectal nodes. • Systemic : Lung,Liver,Brain , Bone
  9. 9. DIAGNOSIS • Diagnosis can be made with visual inspection and anoscopy. • commonly present as polypoidal mass • Distance from anal verge and mobility assessed
  10. 10. • Clinically evident pigmented leision only in 20 % of cases.In others pigmentation is obscured. • 20 % are amelanotic histologically.
  11. 11. THROMBOSED PILE LIKE MASSS
  12. 12. Polypoidal lesion in colonoscopy
  13. 13. DIFFERENTIAL DIAGNOSIS ●Anal carcinoma/lymphoma ●Perianal haematoma ●Thrombosed haemorrhoids ●Anal or Rectal Polyp
  14. 14. INVESTIGATIONS • PROCTOSCOPY & BIOPSY • USG ABDOMEN/PELVIS • ENDOLUMINAL USG • PET ?
  15. 15. ● USG abdomen/pelvis : to r/o liver mets. ● ENDOLUMINAL USG : Depth of invasion and nodal status.
  16. 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. 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. 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. 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. 20. SURGERY • WIDE LOCAL EXCISION / ABDOMINO PERINEAL RESECTION for Stage I/II disease • Wide local excision (R0 resection ) is preferred.
  21. 21. WIDE LOCAL EXCISION • Loan star retractor preferred. • 1 cm margin(R0 resection) . • TEMS for localised leision in rectum
  22. 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. 23. STUDIES • Droesh et al -2005 • 301 pt • 172-APR,129- WLE. • Mean survival same for both.
  24. 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. 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. 26. STAGE III • Systemic chemotherapy • Drugs used are akin to cutaneous melanoma • Commonly used drugs Dacarbazine Temozolamide
  27. 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. 28. PROGNOSTIC FACTORS • Tumour thickness. • Ulceration • Mitotic rate • Nodal involvement. • Relation to dentate line.
  29. 29. PROGNOSIS • STAGE I &II : mean survival 11 – 20 months. • STAGE III : Less than 10 months.
  30. 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. 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. 32. THANK U

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