Ultrasound effective for identifying in-transit metastases in patients with cutaneous melanoma

1. Among patients with cutaneous melanoma, ultrasound evaluation identified in half of patients in-transit metastases that were otherwise not apparent during clinical examination and changed the course of management for a third of patients.

Evidence Leve Rating: 3 (Average)

In-transit metastases (ITMs), or lesions that develop in lymphatics between the primary tumor site and the regional lymph node field, occur in about 4% of patients with cutaneous melanoma. ITMs carry serious prognostic implications; approximately 43% of patients will go on to develop lethal, distant metastases. Thus, reliable ways of identifying ITMs are important for the management of patients with melanoma. This case series from an Australian institution evaluated the impact of using high-frequency ultrasound examination in patients with melanoma and ITMs, specifically looking at the incidence of additional ITMs, the false-positive rate, and the impact on management. 28 patients (median [IQR] age = 72 [63-77] years, 57% male) with a total of 40 ITMs were studied. Ultrasound examination identified additional ITMs in 54% of patients compared with clinical examination alone. Most of these additional ITMs were closer to the regional lymph node field than clinically apparent ITMs. The sensitivity and specificity of detecting additional metastases was 78% and 90%, respectively, with only one false-positive node confirmed after excision. Of note, a previous study found the sensitivity and specificity of PET/CT, a radiation-based imaging modality, for staging patients with ITMs to be 58% and 83%, respectively. Importantly, in 32% of patients, subsequent medical or surgical management was influenced by ultrasound evaluation. In all, this study suggests that ultrasound is a useful staging modality for patients with cutaneous melanoma as it both sensitive and specific for ITMs and has the potential to affect the course of management.

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