Guidelines for imaging in cutaneous melanoma

Pelvic lymph node dissection in metastatic melanoma to the groin should not be abandoned yet

BACKGROUND

In recent years there has been a plea to abandon the pelvic lymph node dissection in the treatment of patients with metastatic melanoma to the groin. A trend towards a conservative surgical treatment is already evolving in several European countries. The purpose of this study is to identify factors associated with pelvic nodal involvement, in order to improve selection of patients whom might benefit from a pelvic nodal dissection.

METHODS

A retrospective analysis was performed on prospectively collected data concerning patients who underwent an inguinal lymph node dissection (ILND) with pelvic lymph node dissection for metastatic melanoma at the University Medical Center Groningen. Multivariable logistic regression analysis was performed to determine factors associated with pelvic nodal involvement. Diagnostic accuracy was calculated for 18F-FDG PET + contrast enhanced CT-scan and 18F-FDG PET + low dose CT-scan.

RESULTS

Two-hundred-and-twenty-six ILND's were performed in 223 patients. The most common histologic subtype was superficial spreading melanoma (42.6%). In patients with micrometastatic disease, 15.7% had pelvic nodal involvement vs 28.2% in patients with macrometastatic disease (p: 0.030). None of the characteristics known prior to the ILND, were associated with pelvic nodal involvement. Imaging methods were unable to accurately predict pelvic nodal involvement. Negative predictive value was 78% for 18F-FDG PET + low dose CT-scan and 86% for an 18F-FDG PET + contrast enhanced CT-scan.

CONCLUSION

There are no patient- or tumor characteristics available that can predict pelvic nodal involvement in patients with melanoma metastasis to the groin. As no imaging technique is able to predict pelvic nodal involvement it seems unjust to abandon the pelvic lymph node dissection.

The clinical use of PET/CT in the evaluation of melanoma

Positron emission tomography combined with computed tomography (PET/CT) has emerged in the last decade as a dominant imaging modality used for staging, monitoring response and surveillance of various cancers, including melanoma. Using 2-deoxy-2-((18)F)fluoro-D-glucose ((18)F-FDG) as the radiopharmaceutical, PET/CT has demonstrated its efficacy and its utility in the management of patients with advanced melanoma. Nonetheless, challenges remain in the early stage evaluation of melanoma and in the development of novel radiotracers to better characterize lesions found on PET/CT. This chapter focuses on the advantages and limitations of this imaging modality in melanoma. We also detail and describe the approach to perform (18)F-FDG PET/CT, the methods to accurately quantify lesions, as well as the pearls/pitfalls of image interpretation. Finally, an overview of preclinical and investigational clinical radiopharmaceuticals is presented.

Preoperative imaging for early-stage cutaneous melanoma: predictors, usage, and utility at a single institution

BACKGROUND

Preoperative imaging for early-stage cutaneous melanoma is not recommended by current guidelines. Our goal was to investigate our institutional usage and utility.

METHODS

Patients with clinically node-negative cutaneous melanoma undergoing surgery with sentinel lymph node biopsy were identified retrospectively. Any melanoma-related imaging after diagnosis and before surgery was considered a staging study.

RESULTS

Five hundred fifteen studies were performed in 409 of 546 (75%) patients. Chest x-rays was performed in 70% and advanced imaging in 14% (computed tomography imaging, magnetic resonance imaging, ultrasound, and positron-emission computed tomography imaging). No metastatic lesions were identified. A Breslow thickness greater than 4 mm (odds ratio = 6.46 vs <1 mm; 95% confidence interval, 2.07 to 20.15) and male sex (odds ratio = 2.62 vs female; 95% confidence interval, 1.26 to 5.46) were associated with an increased likelihood of advanced imaging.

CONCLUSIONS

Preoperative imaging was performed in the majority of patients with node-negative melanoma, with 14% undergoing advanced studies. No metastatic lesions were identified, confirming the limited utility in this setting.

Guidelines for lymphoscintigraphy and F18 FDG PET scans in melanoma

Melanoma has a high potential to develop metastases. Accurate staging is essential for appropriate management. Sentinel node (SN) status is a powerful prognostic factor in early stage melanoma. Staging is assisted by SN biopsy after lymphoscintigraphy to locate all true SNs prior to biopsy. PET using F18-FDG can detect metastases and is used to restage patients with AJCC Stages III and IV disease before planning surgery with curative intent.