Surgery is the most important modality for malignant melanoma. Surgery means wide excision of the primary site, surgical management of clinically normal and abnormal lymph nodes, and surgery for distant metastases.
Wide excision of primary melanoma
The primary treatment modality for malignant melanoma is surgical excision (). After the diagnosis of melanoma has been histologically confirmed and the primary lesion has been adequately staged, a wider and deeper excision is needed. It is reported that melanoma cells may extend micro-satellite fashion from several millimeters to several centimeters from the clinically visible lesion.
Wide excision of malignant melanoma of the plantar area (black line, margin of tumor; red line, margin of wide excision).
Excision margins for melanoma have been a major subject of heated debate in recent years. Recommended surgical margins are based on a prospective randomized controlled study for survival and mortality (). The primary goal of wide excision of malignant melanoma is to achieve a histologically negative margin and prevent local recurrence. Surgical margin recommendations are based on studies in which margins were clinically measured around the primary tumor and including these basic concepts: 1) Wide excision is associated with a reduced risk of local recurrence; 2) there is no evidence in thin melanoma (<1 mm) to confirm the improvement of the survival or local recurrence rate with excision margins exceeding 1 cm; 3) Excision with greater than 2-cm margins offers no benefit in the survival rate or local recurrence [22
Recommended excision margin in malignant melanoma
Melanoma of 1.0 mm or less (T1). Wide excision with a 1.0 cm margin is recommended. However, many surgeons consider 0.5 cm margins the standard of care for excision of melanoma in situ
. For melanoma between the depth of 1.0 and 2.0 mm, 1 to 2 cm margins are adequate while 2 cm margins are adequate for lesions up to 4 mm thickness (). Although patients with lesions above 4 mm in thickness have a relatively high risk of local recurrence, there are few data to support the use of margins wider than 2 cm [23
]. In desmoplastic melanoma, which shows locally aggressive behavior, a resection margin of 3 to 5 cm is needed [23
Wide excision with a 2 cm margin and reconstruction with a thracodorsal artery perforator flap.
Excision margins should be performed with known guidelines, but may involve amputation depending on the anatomical location of the lesion. For more complex areas, such as the perineum, fingers and toes, or where the primary melanoma involves the anatomic areas not amenable to simple wide excision, a multidisciplinary treatment modality should be sought. Caution should be exercised in choosing the width of the margins of in situ melanomas as there are no known randomized studies.
Regarding excision depth, the recommended depth for invasive melanoma has always been to the level of the muscle fascia; no unequivocal evidence exists to support that this is necessary in every circumstance such as in anatomic locations with an a thick fat layer. Although no recommended depth of excision exists, the expert group recommends that, whenever possible, excision should be performed down to the muscle fascia, or at least deep adipose tissue [20
Deciding on the surgical management of the scalp area is challenging because reconstructive options are limited. Even after free flap surgery reconstruction, an additional operation will be needed for resolving the alopecia. Some authors recommend that scalp melanoma should be excised including the 'galea aponeurosis' down through the pericranium. In this clinical situation, reconstruction is difficult because a skin graft is impossible and local flap usage is not desirable due to the risk of recurrence (). Also, malignant melanoma in the head and neck area shows a high mortality compared with other sites, when controlled for other factors [25
Male 54-year-old, 8 mm invasion, T4aN0M0, Stage IIIb. Wide excision and skin grafting was performed.
Ear and face
Wide excision of the lesions in the face is limited to avoid injury or deformity of vital structures which is important for cosmetic results (). The ear is the site of primary malignant melanoma in 7% to 20% of cases of head and neck melanoma [26
]. Depending on the lesion in the ear, in most cases, it is best treated with wedge resection. When the excision has been performed with an initially narrower margin, the surgeon should obtain a negative resection margin. The excision depth should be down to the perichondrium and include the cartilage. Partial or total auriculectomy should be performed in only recurrent or extensive disease. Lymphatic drainage of the ear is to flow to the parotid basin and the superficial parotidectomy and anterior neck dissections are indicated in positive sentinel lymph nodes. The drainage is occasionally into the posterior neck, and level V lymph node dissection should be indicated.
Female 87-year-old, 5 mm invasion, T4bN0M0, Stage IIc. Wide excision with a 2 cm margin and coverage with a local flap and split-thickness skin graft were performed.
Excision of melanoma of the toe or finger is controversial. The traditional method of treatment is amputation of the involved digit. The thumb is the most commonly affected digit in the hand, and loss of its function can be devastating. In primary lesions of the subungal or distal phalanx, the digit should preferentially be amputated at the level proximal to the distal interphalangeal (DIP) joint to preserve as much of the length of the digit as possible (). Kozlow and Rees [27
] insisted that superficial lesions (below 1 mm) could be treated with wide excision. Only in invasive lesions (greater than 1 mm), is amputation of the digit required at one joint proximal to the lesion. For the index finger, ray amputation should be preferred considering the improved functional ability in pinching.
Male 76-year-old, acral lentiginous malignant melanoma with amputation just proximal to the distal interphalangeal joint.
Recent studies have shown that more distal levels of amputation do not compromise the survival or recurrence rate [28
]. Unless the bone is directly involved, total amputation of a finger or ray amputation is not mandated for proximal finger lesions. Also, the digit-sparing approach shows good results [28
]. Adequate soft tissue excision with reconstruction should be performed to prevent functional impairment.
Sentinel lymph node biopsy and lymphadectomy
The initial site of metastasis in melanoma is via the lymphatics in the majority of cases [29
]. In general, nodal metastases in melanoma happen in an ordered manner. Involvement of the sentinel lymph node (SLN) occurs first, then the more distal lymph node (LN) is involved. The incidence of skip metastasis (cases of negative SLN with positive involvement of non-sentinel LN) is <5% [30
]. Lymphatic mapping using lymphoscintigraphy and intraoperative injection of radioisotope and/or blue dye is used to identify the lymph node immediately flown from the primary lesion [30
]. Histologic examination of the sentinel lymph node is known to be the most important prognostic indicator for disease-specific survival of patients with melanoma greater than 1 mm in thickness (T2) [34
]. The overall rate of SLN positivity among patients with intermediate depth melanoma is approximately 15% to 20%, and it significantly decreases in melanoma with less than a 1 mm thickness [37
]. Sentinel lymph node biopsy should be considered in patients with melanoma >1 mm in thickness (T2, 3, and 4), and it is not recommended for patients with melanoma in situ or T1a lesions. In patients with T1b melanoma of 0.76 to 1.00 mm thickness, sentinel lymph node biopsy should be discussed; in T1b melanoma, with tumor thickness <0.75 mm, sentinel lymph node biopsy should not be considered, unless other adverse parameters in addition to ulceration or increased mitotic rate are present, such as angiolymphatic invasion, positive deep margin, or young age [20
]. Some authors recommend sentinel lymph node biopsy for most patients with melanomas >0.76 mm and increased mitotic rate [40