Pathogenesis and treatment of pain caused by skin metastases in neuroendocrine tumours

Prognosis of neuroendocrine tumours has improved during the last decade and one might expect that more patients with (sub)cutaneous metastases will be seen in the future. We investigated the cause of pain in skin metastases and tried to give recommendations about treatment options. We compared histology of (sub)cutaneous metastases in four patients, two with severely painful skin lesions and two without pain. On the pathological slides there were no differences in neuroinvasion, angioinvasion or mitosis between painful and non-painful metastases. However, the painful metastases rapidly multiplied, while the others remained indolent in nature. Pain was very difficult to manage and did not respond to analgesics, irradiation or systemic treatment with interferon or chemotherapy. Local excision was the only successful treatment option. Histology did not show differences between painful and non-painful skin metastases. Local excision is the treatment of choice.