Persistent pain after lymph node excision in patients with malignant melanoma is neuropathic

Persistent postoperative pain is a common complication of surgery, including surgical interventions for cancer. So far, there is limited information about the prevalence and clinical characteristics of pain after lymph node biopsy and dissection in patients with malignant melanoma. In this study, a questionnaire was sent out to all surviving patients (n=402) after surgery for cutaneous malignant melanoma at the Aalborg Hospital Department of Plastic Surgery, Aalborg, Denmark. Of patients responding, sentinel node biopsy (SNB) and/or lymph node dissection (LND) was performed in 175 patients. All patients with pain and a control group were invited to a clinical examination. Altered sensation and pain were significantly more common after LND (82% and 34%, respectively) than after SNB (32% and 14%, respectively). In patients with LND, 12% reported at least moderate pain and 14% impact of pain on quality of life, while in patients with SNB, 3% reported at least moderate pain and 2% pain impact on quality of life. The most important predictor of pain was sensory abnormalities. At the clinical follow-up, 10 out of 12 patients with pain both met the criteria of the recently proposed grading system for probable neuropathic pain and used descriptors on the DN4 questionnaire suggestive of neuropathic pain. Different patterns of sensory profiles were observed in single patients, suggesting heterogeneous sensory processing within single patients. This study suggested that nerve injury was the main underlying mechanism of persistent pain after lymph node excision.