Ultrasound Examination of the Lymphatic Drainage Area and Regional Lymph Nodes in Melanoma Patients with In-Transit Metastases

Background: In-transit metastases (ITMs) are cutaneous or subcutaneous regional metastases that may occur in patients with melanoma. ITMs are often multiple and new lesions tend to appear over time. Ultrasonography can detect impalpable subcutaneous tumors. Objective: The aim of this study was to assess the value of ultrasound examination in detecting additional, non-palpable ITMs and to determine their relevance. Methods: Melanoma patients with ITMs who underwent regional ultrasound examination of the skin and subcutaneous tissue between the wide excision scar of the primary melanoma and the regional lymph node field were identified. In most, ultrasound assessment also included the regional lymph node field. Relevant data were collected and analyzed. Results: Twenty-eight patients presenting with a total of 40 ITMs were included. Ultrasound examination identified additional ITMs in 15 patients (54%). No nodal recurrences were detected. Most additional lesions were found closer to the regional lymph nodes than the original ITMs. Management was influenced by the ultrasound findings in nine patients (32%), five of whom had more extensive surgery, three received systemic drug therapy instead of surgery, and in one patient surgery was delayed and follow-up intensified. In one patient, only subcutaneous fat was found in the excised specimen and the ultrasound was classified as false-positive. Conclusion: In melanoma patients with ITMs, ultrasonography of the lymphatic drainage area provided valuable information, as additional ITMs were identified in more than half of these patients and management was influenced in one-third.