Management of the difficult sentinel lymph node in patients with primary cutaneous melanoma.
Amanda M. Silverio, Matthew C. McRae, Stephen Ariyan, MD, MBA, FACS, Deepak Narayan, MD, FRCS.
Yale University, New Haven, CT, USA.
BACKGROUND: Sentinel lymph node (SLN) mapping and biopsy in primary melanoma define a subset of patients who may benefit from complete lymphadenectomy and trials of adjuvant therapy. We reviewed over 700 SLN cases treated at the Yale Cancer Center Melanoma Unit in which SLN biopsy was complicated by issues of (1) Access to SLN, (2) Visualization of SLN, (3) Altered lymphatic drainage of SLN secondary to surgery, (4) Concurrent and topographically close melanomas, or (5) Aberrant lymphatic drainage outside standard basins. The management of these difficult cases is discussed.
METHODS: Ten patients were identified from over 700 melanoma patients who underwent SLN biopsy for primary cutaneous melanoma at or beyond Stage Ib and who presented with challenges related to access, visualization, and altered lymphatic drainage complicating the detection and harvesting of the SLN. All ten patients underwent preoperative lymphoscintigraphy and intraoperative lymph node mapping with injection of technetium-99 sulfur colloid and Lymphazurin blue dye.
RESULTS: At least one SLN was harvested in all ten patients. Although two had evidence of SLN metastasis, none of the ten patients had evidence of recurrent disease at mean follow-up of 16.6 months (range of 4-33 months).
Access: Two patients presented with SLN that were difficult to access due to location deep to the ribs. One SLN was located anteriorly along the internal mammary chain and the other was found posteriorly under Harrington rods placed for correction of scoliosis. The anterior node was dissected out without rib resection but the latter was abandoned since access would mean repeat spinal instrumentation.
Visualization: Two patients with facial melanomas presented with non-visualised SLNs on preoperative lymphoscintigrams. In one patient the SLN was immediately below the lesion and in the second the SLN was identified by the use of blue dye alone.
Altered drainage: Three patients had undergone previous SLN biopsy or had extensive primary site reconstruction that threatened the accurate identification of lymphatic flow.
Concurrent melanomas: One patient presented with two separate primary melanomas of the back within 2-cm of one another. Despite their close proximity, staged lymphoscintigrams revealed that the melanomas ultimately drained to different basins.
Aberrant drainage: Two patients with truncal melanomas showed uptake in lymphoid tissue outside the standard basins (i.e. neck groin axilla and abdomen). One was in the soft tissue of the chest wall and the other along the intercostal vessels, both of which were confirmed by biopsy.
CONCLUSIONS: Ideally, SLN should be excised and examined for occult melanoma metastases to support accurate staging and therapeutic considerations. However the surgeon must be aware of various pitfalls in SLN node biopsy as illustrated in this case series.