Mid-arm sentinel lymph nodes showing surprising drainage from a malignant melanoma in the forearm

A 51-year-old man with a malignant melanoma in his left forearm was studied to detect the sentinel lymph node and to assess the possibility of micrometastases in regional lymph nodes. Lymphoscintigraphy demonstrated two sentinel lymph nodes in the midarm. Two other nodes in the same location as well as in the left axilla were also observed. The exact location of the sentinel lymph nodes was identified with a gamma-ray detector. At the time of surgery, blue dye was injected around the primary lesion and the two sentinel lymph nodes on the inner side of the left arm were resected. Both lymph nodes were pigmented black. The histopathologic study demonstrated metastases from malignant melanoma in both nodes. This case reflects the main role of lymphoscintigraphy in identifying draining lymph nodes in unusual locations as observed in this patient.