Micrometastasis to in-transit lymph nodes from extremity and truncal malignant melanoma

Background: The sentinel lymph node (SLN) is the first lymph node in the re gional nodal basin to receive metastatic cells. In-transit nodes are found between the primary melanoma site and regional nodal basins. To date, this is one of the first reports on micrometastasis to in-transit nodes. Methods: Retrospective database and medical records were reviewed from Octo ber 21, 1993, to November 19, 1999. At the UCSF Melanoma Center, patients w ith tumor thickness >1 min or <1 mm with high-risk features are managed wit h preoperative lymphoscintigraphy, selective SLN dissection, and wide local excision. Results: Thirty (5%) out of 557 extremity and truncal melanoma patients had in-transit SLNs, Three patients had positive in-transit SLs, and negative SLNs in the regional nodal basin. Two patients had positive in-transit and regional SLNs. Three patients had negative in-transit SLNs but positive reg ional SLNs. The remaining 22 patients were negative for in-transit and regi onal SLNs. Conclusions: In-transit SLNs may harbor micrometastasis. About 10% of the t ime, micrometastasis may involve the in-transit and not the regional SLN. T herefore, both in-transit and regional SLNs should be harvested.