Does injection distance of the radiocolloid modify lymphatic mapping in melanoma?

BACKGROUND. An important factor to be considered when performing lymphogamm agraphy in melanoma patients is the adequate distance of injection of the r adiopharmaceutical from the biopsy excision site or the primary lesion. OBJECTIVE. To test the reproducibility of lymphatic mapping in patients wit h primary cutaneous melanoma who had undergone narrow excisional biopsy by injecting a technetium marker at different distances from the biopsy scar. METHODS. After informed consent, two lymphoscintigraphies were performed on each of 19 melanoma patients, following narrow excisional biopsy. Four ali quots of the radiocolloid were intradermally injected in each procedure, su rrounding the biopsy excision site at 1.5 and 0.5 cm, respectively. RESULTS. Both lymphoscintigraphies showed similar lymph channels and sentin el node(s). CONCLUSION. In melanoma patients who have undergone narrow excisional biops y, lymphoscintigraphy marks with accuracy the sentinel node, at least when the radiopharmaceutical is injected at a distance of less than 1.5 cm from the limits of the biopsy scar.