(A). Lymphoscintigraphy (B) is an important component of the procedure which identifies nodal basin(s) at risk for primary melanomas arising in ambiguous lymphatic drainage sites and the number sentinel nodes in the basin. In panel B, lymphatic drainage from the low back is to the axilla rather thn the closer inguinal basin. Injection of isosulfan blue intradermally around biopsy site in (C), Transcutaneous localization of SLN using gamma detection probe in (D), exploration of nodal basin and visualization of SLN in (E) and (F) and histologic detection of occult metastases in subcapsular sinus in (G).