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Technique for neck dissection
Technique for neck dissection
HNM accounts for up to 25% of all cutaneous melanomas.91 HNM occurs more often in elderly patients, and lesions are more commonly located on the face rather than the scalp, ears, or neck.92 Limited tissue domain, dense arrangement of critical neurovascular structures, and cosmetic considerations in the head and neck region present unique challenges for primary melanoma excision and lymphadenectomy.
Head and neck lymphatics drain in several patterns that are clinically relevant. Lesions of the face and anterior neck often metastasize to the facial, submandibular, and anterior cervical nodes. Lesions located on the posterior scalp and neck frequently drain to the periauricular, posterior occipital, and posterior cervical nodes, while lesions of the anterior scalp, including the forehead, frequently metastasize to the parotid and upper cervical nodes.93 Approximately 25% of HNM nodal metastases are found in the parotid gland, for which parotidectomy with cervical lymphadenectomy should be considered, as 27% patients with parotid involvement will harbor positive nodes in the neck.94 Lymphatic drainage from the ear is variable, but most often includes the periauricular, postauricular, and superior cervical node basins.
De Rosa et al. performed a systemic review of SLNB for HNM in 3,442 patients, and found that 15% had positive SLNs. At dissection, 13.7% of patients were found to have additional positive nodal metastases.58 Neck dissection is currently recommended for patients with known parotid or nodal involvement, and the extent of dissection depends on the disease burden. Martin et al. evaluated their management of 716 patients with cervical lymph node metastases, and found no difference in recurrence between radical, modified radical, and selective neck dissections.95 In general, removal of all levels containing SLNs, as well as second tier levels that are at risk for harboring occult disease, should be considered. Preservation of the sternocleidomastoid, internal jugular, and accessory nerve is nearly always feasible.
Hyperthermic isolated limb perfusion for extremity melanoma
Hyperthermic isolated limb perfusion (HILP) is a surgical procedure that allows for local delivery of highly concentrated chemotherapeutic agents (up to 20 times that
achieved with systemic therapy) to an extremity, avoiding generalized toxicity.96,97 Hyperthermia (40โ43ยฐC) is independently cytotoxic to cancer cells, and has been shown to reduce tumor burden in melanoma.98,99 Combination of the two is thought to have a synergistic cell-killing effect. HILP may be considered in patients with inoperable extremity melanoma, including primary, recurrent, or satellite lesions, but is more commonly utilized for in-transit metastases that are either too extensive for WLE, or are recurrent in nature. HILP has no prophylactic role, and is recommended only for therapeutic use in the presence of known disease.100
HILP is predicated on circulatory isolation of the affected extremity with extracorporeal oxygenation and perfusion, which requires arterial and venous access with large-bore cannulation under direct vision. A proximal tourniquet is placed to limit leakage through the venous system. For the leg, cannulation of the external iliac artery and vein are most common, and for the upper extremity, the axillary artery and vein. Complete vascular isolation of the extremity is critical to prevent systemic toxicity. Therefore large branch vessels of the artery and vein must either be ligated and transected, or transiently occluded with vessel loops or vascular clamps. Once the cannulae are inserted into the vessels by the surgeon, they are connected to an extracorporeal oxygenation perfusion machine, which is composed of a volume reservoir, oxygenator, heat exchanger, and pump. The extremity temperature is monitored with percutaneous thermistors, and there are multiple methods for monitoring systemic chemotherapy leakage, including use of radiolabeled 99mTc, iodine 131, and dye dilution techniques.101โ103 Leak rate greater than 10% should warrant consideration of stopping the perfusion.104
Heated melphalan (L-phenylalanine mustard) has been shown to be effective in clinical trials.100,105,106 Treatment response rates reported in the literature are variable. Complete response occurs in approximately 25% to 50% of patients, whereas partial response is seen in about two-thirds of patients.107โ110 Multiple other agents have also been studied, some in combination, including TNFฮฑ, IFNฮณ, actinomycin, vincristine, cisplatin, fotemustine, and interleukin-2.111,112 However, these agents did not provide better outcomes, and only melphalan is currently used in the United States for HILP.
Regional toxicity from HILP may include extremity edema, erythema, and blistering. Occasionally, patients may develop neuropathy, joint stiffness, and immobility, though vascular complications and compartment syndrome are rare.113 Arterial thrombosis at the arteriotomy site occurs in up to 2% of patients.114 Importantly, more severe regional toxicity is not associated with improved outcomes.115 Signs of systemic toxicity include gastrointestinal upset including nausea, vomiting, and diarrhea. Postoperatively, patients should be monitored closely for signs of extremity swelling, and should undergo serial neurovascular examinations and evaluation for signs of systemic toxicity.