Lymphoscintigraphy in melanoma of the upper and lower limbs: Using 99mTc-Phytate preoperative scintigraphy in identifying sentinel lymph node

Objectives Melanoma is a malignant tumor of melanocytes which are found predominantly in skin. When melanoma begins to lymphogenous metastasis, it follows regular stage which goes to sentinel lymph node(SLN). So we would know the whole lymph nodes' possibility of metastasis with sentinel-lymphogenous metastasis. The administration of preoperative lymphoscintigraphy could help to have clinical information, possibility and ranges of lymphectomy. Especially it could reduce the operation time. In this study, we try to figure out the accurate region of SLN in patient with upper or lower limb melanoma.

Methods We performed lymphoscintigraphic studies in 20 patients with melanoma on the upper or lower limbs for surgery. We used 99mTc-PHYTATE using 26gauge-1cc syringe, 1 mCi per 0.1 ml. We injected the radiopharmaceutical subcutaneously on the site of 12, 3, 6 and 9 clockwise direction which is 2~3mm away from primary tumor each. If the region was on the upper limb we had images on hand, elbow and shoulder. On lower limb, we had ankle, knee and pelvic images. When we had SLN images straightly, we marked on patients' skin on front and lateral point of SLN.

Results In lymphoscintigraphy, 8 patients among 20 had melanoma on upper limb. 2 were found on elbow region and 6 were found on axillary region. 12 patients had melanoma on lower limb. 4 were found on popliteal region and 8 were found SLN on inguinal area. In 16 patients, we found SLN on early static scan. The patients who confirmed SLN on delayed images were 4. After the examination, patients went to an operating room. Lymphoscintigraphy helped to find exact SLN when the surgeon examine with gamma-prove.

Conclusions Lymphoscintigraphy helps to find the SLN in melanoma of the upper or lower limbs quickly and accurately. Moreover, it helps to decide to the range of lymphadenectomy and localization. It could help to prevent metastasis and recurrence to other organs so that the patients' survival time will be longer and it also could reduce the surgery time