Some authors have advocated the use of Mohs micrographic surgery as a tissue-sparing technique. The relapse rate has been reported to be similar to or better than that of wide excision, but comparatively few cases have been treated in this manner and none in randomized, controlled trials.[7,8,9,10][Level of evidence: 3iiiDiii]
Regional Lymph Node Surgery
In some case series, local-regional recurrence rates are high when pathologic nodal staging is omitted. Surgical nodal staging in clinically negative patients has identified positive nodes in at least 25% to 35% of patients.[4,11,12][Level of evidence: 3iiiDiii] In one retrospective series of 213 patients who underwent surgical treatment of the primary tumor and evaluation of the draining nodes, nodal positivity was found in 2 of 54 patients with small tumors (e.g., ≤1.0 cm) and 51 of 159 patients with tumors greater than 1.0 cm.[Level of evidence: 3iiiDiii]
The role of elective lymph node dissection (ELND) in the absence of clinically positive nodes has not been studied in formal clinical trials. In small case series, ELND has been recommended for larger primary tumors, tumors with more than ten mitoses per high-power field, lymphatic or vascular invasion, and the small-cell histologic subtypes.[14,15,16][Level of evidence: 3iiiDiii]
Recently, sentinel lymph node (SLN) biopsy has been suggested as a preferred initial alternative to complete ELND for the proper staging of MCC. SLN biopsy has less morbidity than complete nodal dissection. Furthermore, for MCC sites with indeterminate lymphatic drainage, such as those on the back, SLN biopsy techniques can be used to identify the pertinent lymph node bed(s). If performed, SLN biopsy should be done at the time of the wide resection, when the local lymphatic channels are still intact.
Several reports have found the use of SLN biopsy techniques in MCC to be reliable and reproducible.[17,18,19,20] However, the significance of SLN positivity remains unclear.
- One meta-analysis of ten case series found that SLN positivity strongly predicted a high short-term risk of recurrence and that subsequent therapeutic lymph node dissection was effective in preventing short-term regional nodal recurrence.
- Another meta-analysis of 12 retrospective case series (only partially overlapping the collection of case series in the previous meta-analysis) found that:[Level of evidence: 3iiiDiii]
- SLN biopsy detected MCC spread in one-third of patients whose tumors would have otherwise been clinically and radiologically understaged.
- The recurrence rate was three times higher in patients with a positive SLN biopsy than in those with a negative SLN biopsy (P = .03).
- Between 2006 and 2010, a large, retrospective, single-institutional series of 95 patients (with a total of 97 primary tumors) identified a SLN in 93 instances, and nodal tumor was seen in 42 patients. Immunohistochemical techniques were used to assess node positivity. Various models of tumor and patient characteristics were studied to predict node positivity. There was no subgroup of patients predicted to have lower than 15% to 20% likelihood of SLN positivity, suggesting that SLN biopsy may be considered for all curative patients with clinically negative nodes and no distant metastases.[Level of evidence: 3iiiDiii]
- From 1996 to 2010, another retrospective, single-institutional study of 153 patients with localized MCC who underwent SLN biopsy analyzed factors associated with SLN positivity. The best predictors of SLN biopsy positivity were tumor size and lymphovascular invasion.[22,23][Level of evidence: 3iiiDiii]