Sentinel lymph node biopsy for the staging of anal melanoma: report of two cases.

Primary melanoma of the anal region is a rare pathological entity and its prognosis is generally poor. The aim of this report is to demonstrate the feasibility of the sentinel lymph node (SLN) procedure with combined technique in patients with anal melanoma. We report of two cases with anal melanoma that had wide local excision of the primary lesion and was referred for further evaluation. After diagnostic metastatic work-up, SLN procedure consisted of a combination of preoperative lymphoscintigraphy with technetium-99m nanocolloid injected around the tumor, and intraoperative detection of SLN with gamma probe (combined technique) was performed. In addition, patent blue dye was injected at the periphery of the tumor to facilitate direct identification of the blue-stained lymph node. In the first case, SLN identified both inguinal and iliac lymph node basins, both of which were histologically negative on both frozen and paraffin sections. In the other case, SLN removed from the inguinal lymph node basin showed micrometastasis by paraffin section. In both cases SLN procedure with combined technique was performed sufficiently without significant complications. Consequently, we suggest that SLN procedure with combined technique is also a useful technique in malignant melanomas similar to other anal canal cancers.