The role of ultrasound examination for early identification of lymph-node metastasis of cutaneous squamous cell carcinoma: results from a single institutional center

BACKGROUND: Metastasis from cutaneous squamous cell carcinoma (cSCC) mainly involve the regional nodal basin, with an incidence ranging from 2-4% until 15% in case of high-risk tumors. When dealing with high-risk cSCC, ultrasound examination is recommended every 3-4 months during follow-up. We aimed to determine the role of US examination in the early diagnosis of nodal metastasis from cSCC. METHODS: We conducted a retrospective cohort study enrolling consecutive cases of histopathologically verified cSCCs from January 2007 to March 2018. All the enrolled cases were followed for at least one year and all cases of histopathologically verified metastasis were registered. We also reported if ultrasound of the regional basin was performed between the primary diagnosis and metastasis and how the latter was identified, through ultrasounds or clinically. A Kaplan-Meier survival analysis was conducted on patients undergoing ultrasounds during follow-up. RESULTS: A total of 1881 cases, belonging to 1441 patients were included. Thirty-one cases of nodal metastasis diagnosed after the primary tumor, in as many patients, were identified. All of the selected metastasis derived from high-risk primary cSCCs. Only in 19 cases ultrasound examination was performed during follow-up; of these, 10 were diagnosed through ultrasounds and 9 clinically. Survival analysis demonstrated that the time interval between primary tumor and metastasis was significantly lower for patients with metastasis diagnosed by ultrasounds than clinically (P=0.036). CONCLUSIONS: Our study highlighted the need to optimize the use of nodal ultrasound examination for high-risk cSCCs in order to early detect metastasis.