Teaching Case

Patient with known history of metastatic melanoma presented with large palpable abdominal mass causing significant symptoms of pain, distension and bowel obstruction.

Patient presented with symptoms of severe abdominal pain and distension with a palpable mass and signs of bowel obstruction. Six years ago, he had been diagnosed with metastatic melanoma and over the time he had undergone a variety of treatment options including immunotherapy, surgery, chemotherapy and radiotherapy. Current examination and imaging revealed extensive intra-abdominal and subcutaneous spread of his disease. In particular he had a large (12cm x12cm) palpable mass in the head of the pancreas (Fig1). The patient's pertinent symptoms were from this large pancreatic secondary. Surgical treatment was considered not to be a viable option and after multidisciplinary discussion it was decided that the best palliation for this symptomatic lesion was radiofrequency ablation (RFA) that would help to de-bulk the tumour and reduce the pressure effect. Radiotherapy treatment regime would then carry on. The risks of the RFA procedure including pancreatitis, abscess formation and haemorrhage were explained to the patient. The procedure was performed under sedo-analgesia using ultrasound guidance. The Radionics triple cooled radiofrequency probe (Fig2) was used, and the needle was redirected three times to treat as much of the tumour mass during the one session. Each treatment lasted for 12 minutes; the average wattage used was 140W with an average tissue temperature achieved of over 80 degrees centigrade. Following treatment the patient's symptoms of abdominal pain, distension and bowel obstruction were much improved. The follow-up CT scan (one week) showed a low attenuation area within the tumour mass that represents necrosis; the pancreatic tumour lesion is smaller and there was now less mass effect (Fig 3). The abdomen on examination was softer and the pancreatic tumour lesion less palpable. At four weeks post-procedure, he had developed some further abdominal symptoms of distension and pain. This was not as severe as had been on initial presentation, but as he had had such a good response we were going to ablate the remainder of the pancreatic secondary lesion. However, within the week, the patient's general condition deteriorated further and he developed features of cord neurology with very severe pain in his feet. He was put on a morphine syringe-driver for pain control and he subsequently died a day latter.

One of the most exciting emerging techniques for percutaneous tumour destruction is RFA. Initially pioneered for treatment of small lesions within the central nervous system, RFA is now being used for larger tumour masses - osteoid osteoma, liver tumours, small renal cell carcinomas, lung cancer, and recurrent head and neck tumours. We are not aware of any previous treatment of a pancreatic tumour with RFA. Potential complications for treating pancreatic tumours include pancreatitis, haemorrhage and infection. With such a large lesion as in this patient, there is less concern about bowel ischaemia/perforation, injury to aorta and inferior vena cava including their branches. Many patients may not be surgical candidates for tumour removal because of location, extent of involvement, concomitant debilitating medical conditions, or a history of multiple previous surgeries. These patients can be safely treated with RFA because the procedure can be performed with local anaesthesia and sedation. RFA can be performed in conjunction with radiation therapy to provide the theoretical advantage of greater up-front tumour cytoreduction. The advantages from the use of RFA far outweigh the risks of this minimally invasive procedure.