Utility of computed tomography and magnetic resonance imaging staging before completion lymphadenectomy in patients with sentinel lymph node-positive melanoma

Purpose: Although melanoma patients with regional nodal metastases are frequently imaged with computed tomography (CT) and magnetic resonance imaging (MRI) scans, the efficacy of routine radiologic staging in asymptomatic patients with microscopic nodal involvement has not been established. To determine the utility of this approach, we analyzed the incidence of synchronous distant metastases (SDM) detected by CT or MRI of the head, chest, and abdomen in a large group of patients with sentinel lymph node (SLN) -positive melanoma. Patients and Methods: Positive SLNs were identified in 314 (16.2%) of the 1,934 melanoma patients who underwent sentinel lymphadenectomy at our institution from 1996 to 2003. Within 3 months of sentinel lymphadenectomy, 270 (86.0%) of the 314 SLN-positive patients were radiologically staged. To determine which prognostic factors were associated with SDM, associations between final staging outcomes and clinicopathologic variables, including SLN tumor burden, were analyzed. Results: CT and/or MRI scans identified lesions that were suspicious for SDM in 23 (8.6%) of the 270 patients who underwent staging. In eight of these patients, further diagnostic studies determined that these abnormalities were benign. The remaining 15 suspicious lesions were percutaneously biopsied (10 negative and five positive), yielding a radiologically detectable SDM rate of 1.9%. Detection of SDM was associated with primary tumor thickness (P = .011), ulceration (P = .018), and SLN tumor burden (P = .018). Conclusion: These data suggest that the vast majority of asymptomatic patients with a new diagnosis of microscopic SLN-positive melanoma do not harbor radiologically detectable SDM and can proceed to completion lymph node dissection without immediate CT or MRI staging.