A case series of anal melanoma including the results of treatment with imatinib in selected patients.

AIM: Anal melanoma is a rare malignancy with a poor prognosis.

METHOD: All patients with a diagnosis of anal melanoma treated at a single institution between 2000 and 2012 were identified and their treatment and outcome were evaluated.

RESULTS: Sixteen patients had a median survival of 2.9 years. Fourteen had Stage I or II disease with a median survival of 4.0 years and progression-free survival of 1.5 years. When used for disease staging, whole body positron emission tomography/CT identified an additional three sites of metastasis in five patients compared with CT of the chest, abdomen and pelvis. Surgery involved wide local excision or abdominoperineal excision with respective local recurrence rates of 50% and 66%. Eleven patients underwent testing for c-Kit mutations, of whom five were positive. Four of these were treated with the tyrosine kinase inhibitor imatinib, and showed rapid response of metastases outside the central nervous system.

CONCLUSION: The outcome of this malignancy remains poor. PET is the modality of choice for disease staging. Testing tumours for c-Kit mutations may allow selected patients to participate in trials of tyrosine kinase inhibitors.