Melanoma on the Face
Melanoma occurs rather commonly on the face and most often takes the form of an in situ (Hutchinson’s melanotic freckle or lentigo maligna) or thin invasive lesion. However, despite their diminished biologic aggressiveness, the cosmetic and functional considerations of performing tumor surgery on the face makes treating even these lesions especially challenging.
Surgical biopsy should be performed to fully assess melanoma thickness, in order to appropriately plan definitive surgical treatment of the primary lesion and to determine the risk of regional lymph node metastases and the need for procedures such as lymphatic mapping and sentinel lymphadenectomy. As in other anatomic locations, complete excisional biopsy is the procedure of choice for confirming the diagnosis of melanoma and for measuring lesion thickness. Other techniques such as shave, punch, and incisional biopsy clearly have a role in certain circumstances, but they are less optimal for facial melanomas, since melanocytic neoplasms on the face, melanomas in situ in particular, are often far more extensive microscopically in terms of their radial extension than they appear clinically. If complete excisional biopsy of such a large lesion is required to fully examine the lesion, and the result would be a large surgical defect not amenable to a cosmetically acceptable primary wound closure, the wound should not be closed at that time but should be covered with a moist, sterile dressing until the pathological examination of the surgical specimen is complete. Care should be taken, however, with any biopsy technique chosen, to avoid injury to the branches of the facial nerve. The marginal mandibular division (near the lower jaw), due to its superficial location and diminutive size, is particularly at risk. The possibility of facial nerve injury should be discussed with the patient and documented appropriately prior to any biopsy procedure.
All melanomas, ranging from in-situ to invasive lesions, should be excised with clear margins. However, for melanomas very close to facial structures such as the eye, nose, and mouth, achieving an appropriately wide resection margin may be difficult. A good rule of practice would be to obtain as close to as possible the desired surgical margin based on the thickness of the melanoma. This practice is a reasonable approach in such circumstances, as prospective randomized trials designed to define the width of melanoma excision have demonstrated that thinner margins obtained for melanomas >1 mm in thickness are associated with slightly higher local recurrence rates but have no significant impact in long-term survival.
Traditional resection margin widths for the excision of in situ and thin invasive melanomas have recently been challenged by investigators advocating the technique of Mohs micrographic surgery as an alternative to wider local excision. Preliminary reports on the utility of this technique in the treatment of such melanomas are promising, with acceptably low rates of local recurrence.
A plastic reconstructive surgeon should be included in the planning and performance of any resection of a melanoma on the face that will result in a significant surgical defect. A range of reconstructive techniques is now widely available to make the final cosmetic and functional surgical result more acceptable. All patients should have the advantage of such a multidisciplinary approach to their tumor, with their medical team including a dermatologist, a surgical oncologist, and a plastic reconstructive surgeon.
All patients with melanomas on the face approaching >0.8 mm in thickness are at risk for occult (clinically imperceptible) micrometastases in the regional lymph nodes. Although for many years it has been appreciated that to some extent the anatomic location of the primary melanoma on the head and neck enables a prediction of the most likely site of regional nodal metastasis, the advent and refinement of cutaneous lymphoscintigraphy has better delineated the often complex lymphatic drainage patterns unique to this region. Accordingly, elective lymph node dissection of presumed sites of micrometastatic disease in the head and neck region has for the most part been replaced by cutaneous lymphoscintigraphy, using a combination of intradermally injected vital blue dye and a radio labeled tracer substance such as technetium sulfur colloid, and sentinel lymphadenectomy. Regional lymphadenectomy is performed selectively in those patients with histologically documented micrometastases in the sentinel nodes. Superficial parotidectomy (removal of the parotid gland, the largest of the salivary glands) with dissection of all facial nerve branches is recommended for patients with micrometastases in peri-parotid nodes. Selective cervical lymph node dissection (removal of lymph nodes in the neck) based on the precise location of a positive cervical sentinel node has replaced more traditional and potentially more morbid procedures such as modified radical and formal radical neck dissections. Patients presenting with or developing palpable lymph node metastases in the absence of significant distant metastases should undergo formal regional lymph node dissection as described above.
In a small but not insignificant number of patients with melanoma of the face, preoperative cutaneous lymphoscintigraphy reveals a complex pattern of lymphatic drainage from the primary lesion to multiple sentinel nodes widely dispersed throughout the head and neck region. The diagnostic accuracy may decline and risk of facial and or spinal accessory nerve injury rises as the complexity and number of individual sentinel nodes to be identified and excised increases. Therefore, it seems reasonable to forgo sentinel lymphadenectomy in individualized circumstances when more than two sentinel node sites are revealed by preoperative cutaneous lymphoscintigraphy. The reasons for this decision as well as the risks and benefits of not identifying potential microscopic regional nodal metastases should of course be fully discussed with the patient and carefully documented.