Background
Malignant melanoma is the skin cancer with the highest mortality rate. Accurate detection of regional lymph node metastases is crucial for staging and treatment planning. Small-volume nodal disease may remain occult on cross-sectional imaging, while ultrasound can help detect particularly small regional lymph node metastases. The increasing role of neoadjuvant therapies further emphasizes the importance of early detection.
Case
We present the case of a 63-year-old patient with a 16-mm-thick, ulcerated melanoma of the right thigh, initially classified as Stage IIC. Clinical examination and CT/MRI showed no evidence of metastatic disease. However, ultrasound identified a suspicious, nonpalpable right inguinal lymph node with malignant sonographic features. Due to its proximity to the femoral vessels, CT-guided wire localization was performed prior to surgical excision. Histopathology confirmed an 8-mm lymph node metastasis, resulting in upstaging to Stage IIIC (pN1b). Adjuvant PD-1 inhibition was initiated for BRAF wild-type melanoma.
Conclusion
This case highlights the potential of ultrasound to detect small-volume, radiologically occult lymph node metastases and thereby substantially alter melanoma staging and therapeutic management. In the era of neoadjuvant treatment strategies, early and accurate detection of regional metastatic disease may become increasingly important. Preoperative wire localization represents a feasible option for precise surgical removal of non-palpable lymph node metastases.