The failure of a sentinel node biopsy due to an absence of nodal uptake of nuclear isotope in consecutive melanomas in a single patient – a physiological aberration

Nodal metastasis is an independent prognostic factor in patients with melanoma. Sentinel lymph node biopsy (SNB) is a recommended component of the management of patients with AJCC stage T1b or above. The dermal scar is injected with a Technetium-99 m (99MTc) Nanocolloid, a radiotracer that drains into sentinel nodes to be identified on a preoperative SPECT/CT scan. Intraoperatively the sentinel nodes are located using a gamma probe and patent blue dye. A 79-year-old male was referred to the Plastics Outpatient Department for management of a biopsy proven pT4b melanoma on the right flank and a suspicious lesion on the right shoulder. He was scheduled for a SNB and wide local excision of the flank melanoma and excisional biopsy of the shoulder lesion. He received injections of 99MTc Nanocolloid around the flank biopsy scar, however, preoperative, and intraoperative attempts to locate a node using radiological and surgical techniques were unsuccessful. The biopsy of the shoulder lesion sent for histopathology revealed a pT1b melanoma. A subsequent second SNB on the shoulder melanoma was unsuccessful, as 99MTc Nanocolloid failed to drain into a sentinel node for a second time. The drainage function of lymphatic vessels declines with age however the complete failure of nodal uptake is exceptionally rare. Novel radiotracers such as 99MTc Tilmanocept have shown superior lymph node tracking in recent tracers.