Adequacy of 5-mm surgical excision margins for non-lentiginous melanoma in situ

No Recurrence in Primary Invasive Stage 1a and 1b Melanoma and Melanoma in Situ Treated With Serial Disk Staged Excision

BACKGROUND

Optimal surgical treatment modality for invasive melanoma (IM) and melanoma in situ (MIS) has been debated with proponents for standard wide local excision (WLE), serial disk staged excision, and Mohs micrographic surgery.

OBJECTIVE

The purpose of this study is to identify the recurrence rates and surgical margins of invasive stage 1 melanoma and MIS lesions using serial disk staged excision technique with rush permanent processing and "bread loafing" microscopic analysis.

MATERIALS AND METHODS

Recurrence rates and surgical margins of 63 IM and 207 MIS at the University of California Dermatology Surgery Unit were retrospectively reviewed.

RESULTS

No recurrences were observed with average follow-up of 34 and 36 months for IM and MIS, respectively (range, 10-92 months). Average surgical margins were 19.8 mm (SD 9.7) for IM and 12.1 mm (SD 12.2) for MIS.

CONCLUSION

This SSE technique for the treatment of IM and MIS is comparable in efficacy to other SSE techniques, and it offers physicians a simple and accessible alternative to WLE and MMS.

Local Recurrence of Melanoma Is Higher After Wide Local Excision Versus Mohs Micrographic Surgery or Staged Excision: A Systematic Review and Meta-analysis

BACKGROUND

Complete removal of melanoma is a primary goal of excision, and local recurrence is one measure to evaluate the efficacy of surgical technique.

OBJECTIVE

To compare published local recurrence rates for melanoma treated with Mohs micrographic surgery (MMS) or staged excision versus wide local excision (WLE).

METHODS AND MATERIALS

Search of 6 databases identified comparative and noncomparative studies that reported local recurrence rates after MMS, staged excision, or WLE for melanoma. Random-effects meta-analysis was used to estimate odds ratios and 95% confidence interval (CI) from comparative studies and event rates from noncomparative studies.

RESULTS

Of the 71 studies included (16,575 patients), 12 were comparative studies (2,683 patients) and 56 were noncomparative studies (13,698 patients). Comparative studies showed increased recurrence after WLE compared with MMS or staged excision (odds ratio [OR], 2.5; 95% CI, 1.4-4.6) and compared with MMS alone (OR, 3.3; 95% CI, 1.8-5.9). Pooled data from comparative and noncomparative studies showed a local recurrence rate of 7% after WLE (95% CI, 5%-11%), 3% after staged excision (95% CI, 2%-4%), and less than 1% after MMS (95% CI, 0%-1%). Statistical heterogeneity was moderate to high.

CONCLUSION

Local recurrence of melanoma is significantly lower after MMS (<1%) and staged excision (3%) compared with WLE (7%).

Melanoma: Staging and Follow-Up

Cancer staging is the process determining to which extent a cancer has spread and where it is located in the body. A thorough staging is of utmost importance, not only because it provides the most accurate prognostic estimation, but also because several crucial decisions, such as the treatment choice and the follow-up strategy, vary according to the tumor's stage. The current staging system for melanoma is based on the 8^th edition of TNM classification issued by the American Joint Committee on Cancer (AJCC) in 2017. It includes a clinical and a pathological staging, both consisting of 5 stages (0-IV). The stage of a melanoma is determined by several factors, among which the Breslow thickness, the pathological presence or absence of ulceration in the primary tumor, the presence and the number of tumor-involved regional lymph nodes, the presence or absence of in-transit, satellite and/or microsatellite metastases, and the presence of distant metastases. Following melanoma diagnosis, an accurate medical workup, in line with the stage and the physical examination, should be performed. A continuous patient monitoring is fundamental to detect a potential relapse or a second primary melanoma and should be lifelong. However, there is still no universally adopted follow-up strategy program and different follow-up schemes have been suggested. Future prospective studies are needed to evaluate different follow-up protocols according to the adopted therapy, as novel recent therapies (targeted and immunotherapies) are being increasingly used. Key MessagesProper staging is of utmost importance because it provides accurate prognostic estimation. Several crucial decisions, such as the treatment choice and the follow up strategy, are based on the tumor stage.Physical examination during staging procedure and follow-up visits are important to avoid unnecessary imaging and laboratory tests that could increase the patients' anxiety. A personalized approach taking into consideration the patient's risk factors, is strongly recommended.Melanoma patients should be kept under surveillance lifelong due to an increased risk of developing a second primary melanoma and the risk of recurrence. Higher intensity follow-up strategies during the first 5 years are recommended due to higher rates of regional or distant relapse.

Melanoma In Situ: A Critical Review and Re-Evaluation of Current Excision Margin Recommendations

Most international clinical guidelines recommend 5-10 mm clinical margins for excision of melanoma in situ (MIS). While the evidence supporting this is weak, these guidelines are generally consistent. However, as a result of the high incidence of subclinical extension of MIS, especially of the lentigo maligna (LM) subtype, wider margins will often be needed to achieve complete histologic clearance. In this review, we assessed all available contemporary evidence on clearance margins for MIS. No randomized trials were identified and the 31 non-randomized studies were largely retrospective reviews of single-surgeon or single-institution experiences using Mohs micrographic surgery (MMS) for LM or staged excision (SE) for treatment of MIS on the head/neck and/or LM specifically. The available data challenge the adequacy of current international guidelines as they consistently demonstrate the need for clinical margins > 5 mm and often > 10 mm. For LM, any MIS on the head/neck, and/or ≥ 3 cm in diameter, all may require wider clinical margins because of the higher likelihood of subclinical spread. Histologic clearance should be confirmed prior to undertaking complex reconstruction. However, it is not clear whether wider margins are necessary for all MIS subtypes. Indeed, it seems that this is unlikely to be the case. Until optimal surgical margins can be better defined in a randomized trial setting, ideally controlling for MIS subtype and including correlation with histologic excision margins, techniques such as preliminary border mapping of large, ill-defined lesions and, most importantly, sound clinical judgement will be needed when planning surgical clearance margins for the treatment of MIS.

Histological Peripheral Margins and Recurrence of Melanoma In Situ Treated with Wide Local Excision

Background

The incidence of melanoma in situ (MIS) is increasing faster compared to invasive melanoma. Despite varying international practice, a minimum of 5 mm surgical excision margin is currently recommended in the UK. There is no clear guidance on the minimum histological peripheral clearance margins.

Aim

This study compares the histological peripheral clearance margins of MIS using wide local excision (WLE) to the rate of recurrence and progression to invasive disease.

Methods

A retrospective single-center review was performed over a 5-year period. Inclusion criteria consisted of MIS diagnosis, ≥16 years of age, and treatment with WLE with curative intent. Those patients with a recurrence of a previous MIS or with a reported focus of invasion/regression were also included. Clinicopathological data and follow-up were recorded.

Results

167 MIS were identified in 155 patients, 80% of which were lentigo maligna subtype. Of patients with completely excised MIS on histology (>0 mm), 9% had recurrence with a median time to recurrence of 36 months. Three (1.8%) cases recurred as invasive disease. Age, MIS site, MIS subtype, and histological evidence of foci of invasion/regression did not predict recurrence nor progression to invasive disease (p > 0.05). The recurrence rate of MIS with a histological excision margin ≤3.0 mm was 13% compared to 3% in those with histology margins of >3.0 mm (p=0.049).

Conclusion

A histological peripheral clearance of at least 3.0 mm is advocated to achieve lower recurrence rates. The follow-up duration should be reviewed due to the median recurrence occurring at 36 months in our cohort. Cumulative work on MIS needs to be collated and completed in a large multicenter study with a long follow-up period.

Induction of G0/G1 phase arrest and apoptosis by CRISPR/Cas9-mediated knockout of CDK2 in A375 melanocytes

Cutaneous melanoma is one of the most common malignant skin tumors, with a continuously increasing incidence. Cyclin-dependent kinase (CDK) 2 is a key regulator of G1-S transition and modulation of G2 progression; however, its role in cancer is a matter of debate. In the present study, a lentivirus expressing single-guide RNA (sgRNA) was constructed to knock out CDK2 using CRISP/Cas9 technology, in order to confirm the role of CDK2 in A375 human melanoma cells. The results demonstrated that CDK2 knockout induced G0/G1 phase arrest and early apoptosis by downregulating the expression of CDK4 and cyclin A2, and by upregulating the expression of cyclin D1. These results suggest that therapeutic strategies designed to target CDK2 using CRISP/Cas9 may improve the treatment outcome of cutaneous melanoma.

Update on Current Treatment Recommendations for Primary Cutaneous Melanoma

Primary cutaneous melanoma describes any primary melanoma lesion of the skin that does not have evidence of metastatic disease. This article reviews the current workup, treatment, and follow-up recommendations for primary cutaneous melanoma (stages 0, I, and II). Specific attention is focused on recent updates with regard to staging, sentinel lymph node biopsy, and surgical modalities.

Comparison of surgical margins for lentigo maligna versus melanoma in situ

BACKGROUND

Multiple studies have shown a 5-mm surgical margin to be inadequate for excision of melanoma in situ. Some have suggested that a wider margin is needed only for the lentigo maligna subtype.

OBJECTIVE

To compare subclinical extension of lentigo maligna with that of melanoma in situ. The secondary objective was to investigate the effect of other factors on extent of subclinical extension.

METHODS

A prospectively collected series of noninvasive melanomas was studied. Original pathology reports were used to identify lentigo maligna and compare data for that subtype with data for the remaining melanomas in situ.

RESULTS

A total of 1506 lentigo maligna cases and 829 melanomas in situ were included. To obtain a 97% clearance rate, both lentigo maligna and melanoma in situ required a 12-mm margin on the head and neck and a 9-mm margin on the trunk and extremities. Only 79% of lentigo maligna and 83% of melanoma in situ were successfully excised with a 6-mm margin (P = .12). Local recurrence was identified in 0.26% (5 facial, 1 scalp, and 1 acral), with a mean follow-up time of 5.7 years.

LIMITATIONS

Margins less than 6 mm were not studied. The use of lentigo maligna diagnosis was not used by all dermatopathologists consistently. The degree of surrounding photodamage was not assessed.

CONCLUSION

Subclinical extension of lentigo maligna and melanoma in situ are similar. Standard surgical excision of all melanoma in situ subtypes, including lentigo maligna, should include at least 9 mm of normal-appearing skin, which is similar to the amount recommended for early invasive melanoma. Lesions on the head and neck or those with a diameter greater than 1 cm may require even wider margins and are best treated with Mohs micrographic surgery. The perception that lentigo maligna has wider subclinical extension may be related to its frequent location on the head and neck, where photodamage can camouflage the clinical border.

Management of Early-Stage Melanoma

Melanoma is a potentially aggressive skin cancer with a steadily rising incidence. Most melanomas are diagnosed at an early stage and associated with an excellent prognosis when treated appropriately. Primary treatment for melanoma is surgical. Wider surgical margins and a variety of techniques for comprehensive histologic margin assessment may be considered for lentigo maligna type melanoma on the head and neck, due to characteristic broad subclinical extension. For invasive melanoma, sentinel lymph node biopsy may be indicated for staging, and to guide further management and follow-up. Appropriate treatment guidelines for early-stage melanoma are reviewed and discussed.

Guidelines of care for the management of primary cutaneous melanoma

The incidence of primary cutaneous melanoma continues to increase each year. Melanoma accounts for the majority of skin cancer-related deaths, but treatment is usually curative following early detection of disease. In this American Academy of Dermatology clinical practice guideline, updated treatment recommendations are provided for patients with primary cutaneous melanoma (American Joint Committee on Cancer stages 0-IIC and pathologic stage III by virtue of a positive sentinel lymph node biopsy). Biopsy techniques for a lesion that is clinically suggestive of melanoma are reviewed, as are recommendations for the histopathologic interpretation of cutaneous melanoma. The use of laboratory, molecular, and imaging tests is examined in the initial work-up of patients with newly diagnosed melanoma and for follow-up of asymptomatic patients. With regard to treatment of primary cutaneous melanoma, recommendations for surgical margins and the concepts of staged excision (including Mohs micrographic surgery) and nonsurgical treatments for melanoma in situ, lentigo maligna type (including topical imiquimod and radiation therapy), are updated. The role of sentinel lymph node biopsy as a staging technique for cutaneous melanoma is described, with recommendations for its use in clinical practice. Finally, current data regarding pregnancy and melanoma, genetic testing for familial melanoma, and management of dermatologic toxicities related to novel targeted agents and immunotherapies for patients with advanced disease are summarized.

Amelanotic Lentigo Maligna Melanoma: Mohs Surgery as the Definitive Treatment of an Invisible Tumour

Amelanotic lentigo maligna melanoma represents <2% of melanomas. Diagnosis is delayed owing to the lack of lesion pigmentation and advanced disease at presentation. Excision with appropriate margins is the treatment standard, but the starting point for such margins is often unclear. We describe 2 patients with amelanotic melanoma treated by Mohs micrographic surgery (MMS) that would not have been cleared by wide local excision alone and provide an extensive review of the literature. Both patients presented with histologic diagnoses of malignant melanoma, one with a barely perceptible biopsy site scar on the left infraorbital cheek/lower eyelid (Breslow 1.8 mm) and the second with an amelanotic tumour on the right helix (Breslow 10 mm). Due to location, aggressive histology, amelanotic appearance, and no apparent surrounding skin surface changes, MMS was elected to maximise margin control. For patient 1, invasive and in situ tumour was found at the American Joint Committee on Cancer–recommended margin of 1.5 cm, and the final defect measured 8.5 × 4.8 cm. Patient 2 had a significant invasive and amelanotic lentigo maligna component, resulting in a 9.0 × 6.5-cm defect. MMS allows for immediate histologic feedback on tumour margins of a clinically invisible tumour and thus offers the most definitive treatment.