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Sentinel lymph-node biopsy after previous wide local excision for melanoma
D R McCready1, D M Ghazarian, M S Hershkop
1Department of Surgical Oncology, University Health Network, Princess Margaret Hospital, University of Toronto, Ont.
Objective:
To document experience with sentinel lymph-node biopsy in patients who have already undergone a wide local excision for melanoma because in many centres previous wide excision has been a contraindication for sentinel lymph-node biopsy.
Design:
A prospective cohort study.
Setting:
A tertiary care academic cancer centre.
Patients:
One hundred patients who presented with cutaneous melanoma (depth >1 mm or Clark level IV) after having undergone wide local excision of the primary lesion that was not situated in the head or neck. The follow-up was 3 years.
Interventions:
Sentinel lymph-node biopsy. Patients with truncal melanoma had preoperative lymphoscintigraphy to document the nodal basins at risk. Technetium-99m sulfur colloid (0.5-1 mCi in 0.5 mL) was injected intradermally around the scar, and the sentinel lymph node was excised with the aid of a hand-held gamma detector.
Outcome Measures:
Accuracy of the biopsy and false-negative rates in this setting.
Results:
Of the 100 patients, 44 had truncal and 56 had extremity lesions. The average tumour depth was 3.47 mm and 3.07 mm respectively. Thirty-one patients had a sentinel lymph node positive for melanoma metastasis. Biopsies were positive for melanoma in 18 (41%) truncal lesions and 13 (23%) extremity lesions. There were 3 (9%) false-negative sentinel lymph-node biopsies as diagnosed by clinically evident nodal disease subsequently appearing in the nodal basin subjected to biopsy. Two occurred in patients after large rotation flap closures of truncal lesions. The third patient had a subungual melanoma of the great toe. No disease was found in the 2 nodes dissected. Two of the 3 false-negative biopsy results were obtained before serial sections and immunohistochemical staining were used to examine the sentinel lymph nodes.
Conclusions:
Sentinel lymph-node biopsies can successfully identify clinically occult nodal metastases in patients who have had previous wide local excision of a melanoma, but the false-negative rate in patients with rotation flap closures should be taken into consideration.