A technique for lymphoscintigraphy and sentinel node dissection for melanomas of the head and neck

Abstract

Melanoma of the head and neck is an increasingly frequent lesion that is often managed by the otolaryngologist/head and neck surgeon [1], partly because of an explosion of this disease, a disproportionate presence on the head and neck [2], and an increased appreciation for its management by members of this specialty [3]. Melanomas with a Breslow depth greater than 0.75 mm are considered to be at moderate to high risk for occult nodal metastasis. Because more adjuvant treatment is now available, patients who undergo aggressive regional staging and have positive disease might experience a survival benefit from additional therapy. This issue is easily settled by lymphoscintigraphy and sentinel node dissection (SND). Discovery of subclinical nodal metastases increase the melanoma stage (usually to stage III), making the patient eligible for adjuvant therapy, which can take the form of elective lymph node dissection (ELND), neck radiation, or immunotherapy. Additionally, an increased public awareness of melanoma vaccines has increased the profile of lymphoscintigraphy/SND in the management of melanoma. The concept of a sentinel node draining a malignancy has existed for decades [4], but it was developed into a clinical procedure by Morton and colleagues in the early 1990s [5]. Since this initial report, radioguided surgery has proliferated in its use for staging melanoma and has been popularized for breast cancer and other malignancies [1,6–8]. As a result, many major medical centers already possess the necessary equipment for this technique, and it can be effectively incorporated into a head and neck practice. This article reviews the equipment and procedures required to perform lymphoscintigraphy and SND on patients suffering from melanoma of the head and neck. The emphasis in this review will be on the surgical exercise [9]. Nuclear medicine physicians are familiar with basic principles and practice of lymphatic mapping, and it is also described in their literature [10]. Indications for this technique are briefly mentioned but are discussed at length elsewhere in this issue. There are four major reasons to perform SLN biopsy: (1) SLN biopsy improves the accuracy of TNM staging and provides valuable prognostic information to guide subsequent treatment decisions, (2) SLN biopsy can result in early therapeutic lymph node dissection for patients with nodal metatases, (3) SLN biopsy identifies patients who are candidates for adjuvant therapy with interferon alfa-2b, and (4) SLN biopsy identifies patients for entry into clinical trials of novel adjuvant therapy agents (vaccines). Overall, the benefit of accurate nodal staging obtained by SLN biopsy far outweighs the risks and has important implications for patient management [11]. When a patient has a suspicious melanotic lesion of the head and neck, a biopsy is often performed to assess its histology. This is often times performed prior to surgical referral. Occasionally, the lesions are shaved or completely excised, which can result in confusion in interpreting the pathology report with respect to thickness and margins, respectively. If the lesion is confirmed to be malignant melanoma, Clarke’s level and Breslow depth are usually reported. In the author’s institution, when head and neck lesions are greater than 0.75 mm in thickness, patients are offered lymphoscintigraphy, intraoperative lymphatic