We report the case of a 12-year-old male child with malignant melanoma on his left thigh. Sentinel node biopsy was preformed with blue dye and radioisotope using gamma probe. 99mTc-stannous phytate (particle size: 200-1000nm) was used as a radiolabeled tracer. Prophylactic inguinal lymph node dissection was also performed in parallel with sentinel node dissection, which resulted in two radioactive blue nodes among 14 nodes dissected. Although the guidelines for sentinel node biopsy in Japan have not been established, a survey of the literature suggests that sentinel node biopsy is a more appropriate modality for the treatment of malignant melanoma. The tentative criterion for sentinel nodes in our institute is all nodes that show at least 10% counts of the hottest radioactive node and/or all blue-dye stained nodes. [Skin Cancer (Japan) 2002; 17: 269-273]
