Systematic review and meta-analysis of local recurrence rates of head and neck cutaneous melanomas after wide local excision, Mohs micrographic surgery, or staged excision

Mohs micrographic surgery for the treatment of invasive melanoma: A systematic review with meta-analyses

BACKGROUND

The use of Mohs micrographic surgery (MMS) in melanoma treatment has divided opinion and evidence-based guidelines are lacking.

OBJECTIVES

This systematic review aimed to analyse clinical outcomes for patients with invasive melanomas treated with Mohs rather than wide local excision (WLE).

METHODS

Embase, MEDLINE and Cochrane databases (to 30 August 2023) were searched for studies using Mohs to treat invasive melanoma. Outcomes of interest were local recurrence and death from melanoma.

RESULTS

Thirty-five articles involving 41,499 patients with invasive melanoma treated with Mohs were identified. Sixteen studies compared Mohs with WLE and 19 were Mohs-only, non-comparative studies. Patients treated with Mohs differed significantly from those undergoing WLE, in particular Mohs patients were older and had thinner melanomas. Two comparative studies using the same data source reported adjusted hazard ratios for melanoma-specific death and both showed no significant difference between Mohs and WLE-treated patients; 0.87 (95% CI 0.55-1.35) and 1.20 (95% CI 0.71-20.36). There was also no statistically significant difference in local recurrence risk; the unadjusted risk ratio for patients treated with Mohs was 0.46 (95% CI 0.14-1.51 p = 0.20) with moderate heterogeneity (I2 = 62%). No studies reported multivariable analyses for risk of local recurrence. Many studies generated from relatively few and often overlapping data sets have reported the use of Mohs to treat patients with invasive melanoma. Fewer studies were comparative between Mohs and WLE and these reported substantially different baseline risks of recurrence and death from melanoma between the groups. Mohs has generally been used for thinner melanomas in older patients; therefore, comparisons based on univariable analyses are likely to have been misleading.

CONCLUSIONS

On the basis of currently available data, it is not possible to reliably assess whether outcomes differ if invasive melanomas with comparable features are treated with Mohs or WLE, and randomized trial evidence will be required for reliable conclusions to be reached.

Review on the Role of Paraffin-embedded Margin-controlled Mohs Micrographic Surgery to Treat Skin Tumors

Paraffin-embedded margin-controlled Mohs micrographic surgery (PMMS) includes various procedures such as slow Mohs or deferred Mohs technique, the Muffin and Tübingen techniques, and staged margin excision, or the spaghetti technique. PMMS is a variation of conventional Mohs micrographic surgery (MMS) that allows histopathological examination with delayed margin control. PMMS requires minimum training and may be adopted by any hospital. The setback is that PMMS can require procedures across multiple days. PMMS lowers the rate of recurrence of basal cell carcinoma vs wide local excision in high-risk basal cell carcinoma, and improves the rates of recurrence and survival in lentigo maligna. PMMS can be very useful in high-risk squamous cell carcinoma treatment. Finally, it is a promising technique to treat infrequent skin neoplasms, such as dermatofibrosarcoma protuberans, or extramammary Paget's disease, among others. In this article, we present a literature narrative review on PMMS, describing techniques and indications, and highlighting long-term outcomes.

Review on the Role of Paraffin-embedded Margin-controlled Mohs Micrographic Surgery to Treat Skin Tumors

Paraffin-embedded margin-controlled Mohs micrographic surgery (PMMS) includes various procedures such as slow Mohs or deferred Mohs technique, the Muffin and Tübingen techniques, and staged margin excision, or the spaghetti technique. PMMS is a variation of conventional Mohs micrographic surgery (MMS) that allows histopathological examination with delayed margin control. PMMS requires minimum training and may be adopted by any hospital. The setback is that PMMS can require procedures across multiple days. PMMS lowers the rate of recurrence of basal cell carcinoma vs wide local excision in high-risk basal cell carcinoma, and improves the rates of recurrence and survival in lentigo maligna. PMMS can be very useful in high-risk squamous cell carcinoma treatment. Finally, it is a promising technique to treat infrequent skin neoplasms, such as dermatofibrosarcoma protuberans, or extramammary Paget's disease, among others. In this article, we present a literature narrative review on PMMS, describing techniques and indications, and highlighting long-term outcomes.

Intraoperative Immunohistochemistry During Mohs Micrographic Surgery and Staged Excision Decreases Local Recurrence Rates for Invasive Cutaneous Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Mohs micrographic surgery (MMS) is increasingly used to treat cutaneous melanoma. However, it is unclear whether intraoperative immunohistochemistry (IHC) improves surgical outcomes.

OBJECTIVE

To determine whether intraoperative IHC during MMS and staged excision is associated with a decreased risk of poor surgical outcomes.

MATERIALS AND METHODS

Search of 6 databases identified comparative and noncomparative studies that reported local recurrence after MMS or staged excision with or without IHC for melanoma. Random-effects meta-analysis was used to estimate pooled local recurrence rates, nodal recurrence, distant recurrence, and disease-specific mortality.

RESULTS

Overall, 57 studies representing 12,043 patients with cutaneous melanoma and 12,590 tumors met inclusion criteria. Combined MMS and staged excision with IHC was associated with decreased local recurrence in patients with invasive melanoma (0.3%, 95% CI: 0-0.6) versus hematoxylin and eosin alone (1.8%, 95% CI: 0.8%-2.8%) [p < .001]. Secondary outcomes including nodal recurrence, distant recurrence, and disease-specific mortality were not significantly different between these 2 groups. Study heterogeneity was moderately-high.

CONCLUSION

Local recurrence of invasive melanoma is significantly lower after MMS and staged excision with IHC as opposed to without IHC. These findings suggest that the use of intraoperative IHC during MMS or staged excision should strongly be considered, particularly for invasive melanoma.Trial Registration PROSPERO Identifier: CRD42023435630.

Double Immunohistochemical Labelling of PRAME and Melan A in Slow Mohs Biopsy Margin Assessment of Lentigo Maligna and Lentigo Maligna Melanoma

Introduction: Lentigo maligna (LM) and lentigo maligna melanoma (LMM) predominantly affect the head and neck areas in elderly patients, presenting as challenging ill-defined pigmented lesions with indistinct borders. Surgical margin determination for complete removal remains intricate due to these characteristics. Morphological examination of surgical margins is the key form of determining successful treatment in LM/LMM and underpin the greater margin control provided through the Slow Mohs micrographic surgery (SMMS) approach. Recent assessments have explored the use of immunohistochemistry (IHC) markers, such as Preferentially Expressed Antigen in Melanoma (PRAME), to aid in LM/LMM and margin evaluation, leveraging the selectivity of PRAME labelling in malignant melanocytic neoplasms. Methods: A Novel double-labelling (DL) method incorporating both PRAME and MelanA IHC was employed to further maximise the clinical applicability of PRAME in the assessment of LM/LMM in SMMS biopsies. The evaluation involved 51 samples, comparing the results of the novel DL with respective single-labelling (SL) IHC slides. Results: The findings demonstrated a significant agreement of 96.1% between the DL method and SL slides across the tested samples. The benchmark PRAME SL exhibited a sensitivity of 91.3% in the SMMS specimens and 67.9% in histologically confirmed positive margins. Discussion: This study highlights the utility of PRAME IHC and by extension PRAME DL as an adjunctive tool in the assessment of melanocytic tumours within staged excision margins in SMMS samples.

Clinical Characteristics of Marginally Recurrent Melanoma After Primary Excision: A Multisite Retrospective Analysis of 140 Cases Referred for Mohs Surgery

BACKGROUND

Marginally recurrent melanoma (MRM) manifests immediately adjacent to or within a scar and arises from incomplete tumor clearance after primary treatment. Little is known about the progression and treatment of MRM after all forms of excision.

OBJECTIVE

To determine the invasive growth potential, tumor-stage progression, and outcomes of those with MRM.

METHODS

One hundred forty patients with MRM were collected from 5 practice databases. All patients were treated with Mohs micrographic surgery. They were evaluated for Breslow depth and tumor stage change from the time of primary treatment and recurrent treatment.

RESULTS

Of 101 cases initially treated as melanoma in situ, 13 (12.9%) marginally recurred with invasive disease at the time of Mohs micrographic surgery. The median thickness of these recurrent melanomas was 0.58 mm. Of 39 cases initially treated as invasive melanoma, 10 (25.6%) marginally recurred with a greater Breslow depth. The median increase in thickness from initial treatment to recurrence was 1.31 mm.

CONCLUSION

Marginally recurrent melanoma retains its invasive growth potential. This can lead to Breslow depth increase, tumor-stage progression, and a worse prognosis on recurrence. Obtaining tumor-free margins is critical in initial and recurrence treatments.

An Update and Review of Clinical Outcomes Using Immunohistochemical Stains in Mohs Micrographic Surgery for Melanoma

BACKGROUND

Mohs micrographic surgery (MMS) provides optimal margin control through complete peripheral and deep margin assessment. The treatment of melanoma using MMS has historically been limited by difficulty in interpreting melanocytes using frozen sections. Immunohistochemical (IHC) staining, a technique whereby chromogen-tagged antibodies are used to detect antigens of interest, has revolutionized the surgical treatment of melanoma.

OBJECTIVES

This article provides an update and literature review of current IHC stains used in MMS for melanoma, their sensitivities and specificities, and clinical outcomes.

MATERIALS AND METHODS

A PubMed search was performed using keywords including "immunohistochemistry," "staining," and "Mohs surgery." Articles related to the use of IHC staining for the treatment of melanoma with MMS were included.

RESULTS

Six IHC stains met the criteria for the review including melanoma antigen recognized by T cells (MART-1), SRY-related HMG-box (SOX10), microphthalmia-associated transcription factor, HMB-45, MEL-5, S-100, and preferentially expressed antigen in melanoma.

CONCLUSION

The adaptation of IHC methods to frozen sections has enabled MMS to become a preferred treatment option for melanoma in special-site areas. Future studies are needed to standardize IHC techniques and to define best practices when using frozen section in the treatment of melanoma.

Disease-specific survival of malignant melanoma after Mohs micrographic surgery is not impacted by initial margins: A systematic review and meta-analysis

Background

During Mohs surgery for melanoma, evidence has demonstrated that many surgeons opt for smaller initial margins than traditionally recommended (0.5 cm for in situ and 1 cm for invasive). Literature regarding surgical outcomes based on initial margin is sparse.

Objective

To determine differences in disease-specific survival of melanoma after Mohs micrographic surgery for varied initial surgical margins.

Methods

A literature search was conducted on February 14, 2022, from MEDLINE via PubMed (1946-present), Embase (1974-present), Central (1991-present), and Scopus (1960-present). The primary outcome was disease-specific mortality.

Results

Nineteen studies were included for final analysis. The overall disease-specific mortality rate of melanoma in all included studies was 0.5% (CI, 0.1-0.8; P, .010). Disease-specific mortality for 1 to 5, 5, and 6 to 10 mm categories were 0.4% (CI, 0.0-0.9; P, .074), 0.7% (CI, 0.2-1.3; P, .2-1.3), and 0.4% (CI, -0.9 to 1.8; P, .524), respectively. None of the variances across initial margin categories were statistically significant.

Limitations

Early-stage melanomas have low overall mortality rates. In our associated article, initial margins of 5 to 10 mm were shown to have the lowest rates of local recurrence.

Conclusions

In this systematic review and meta-analysis, melanoma-specific mortality was not significantly impacted by the initial surgical margin taken during Mohs micrographic surgery.

From Centimeters to Millimeters: The Evolution of the Surgical Margins for Melanoma-A Historical Review

BACKGROUND

With an improved understanding of tumor biology and behavior, the recommended margins for the surgical treatment of melanoma have evolved.

OBJECTIVE

We describe the progression of these surgical margins, detailing the historical basis for the 5-cm margin and transitioning to current practice, in which Mohs micrographic surgery (MMS) with immunohistochemistry (IHC) has become increasingly used.

METHODS/MATERIALS

We searched PubMed and Google Scholar for articles published between January 2019 and April 2023 describing the use of MMS for melanoma in situ (MIS) and invasive melanomas.

RESULTS

We identified 12 articles focusing on the use of MMS for MIS and invasive melanomas: 3 meta-analyses and 9 retrospective studies. Two retrospective analyses documented no differences in overall survival between MMS and wide local excision (WLE) and 2 found improved overall survival for MMS compared with WLE. Three retrospective analyses and 3 meta-analyses demonstrated low recurrence rates after the use of MMS for both MIS and invasive melanomas. Finally, 2 retrospective studies documented the success of MMS with IHC using MART-1.

CONCLUSION

Over the past century, the surgical margins for the treatment of melanoma have undergone a marked transformation. MMS with IHC has become increasingly popular given its ability to reliably produce superior clinical outcomes.

Histologic margin status is a predictor of relapse in lentigo maligna melanoma

BACKGROUND

Most surgical margins for lentigo maligna melanomas reported in the literature are clinical and not histologic.

OBJECTIVES

We sought to determine whether histologic margin status is an independent predictor of progression.

METHODS

Clinicopathologic information of 268 invasive lentigo maligna melanomas diagnosed from 1990-2019 were analyzed. Statistical analyses were performed using Cox proportional hazards model and Boruta method.

RESULTS

A total of 75% of the lesions were located on the head and neck. The range of follow-up for all patients was 0 to 31.8 years (median, 10.2 years). Time to local recurrence ranges from 0 to 20 years (median, 3 years). Progression developed in 54 (20.1%) of 268 patients. Local recurrence was seen only in 36 (13.4%), both local recurrence and subsequent metastasis in 7 (2.6%), and only metastasis in 11 (4.1%) of 268 patients. Histologic margin status (positive and close/<3 mm) and tumor site (head and neck location) significantly correlated with worse progression-free survival.

LIMITATIONS

Single institution and retrospective study.

CONCLUSIONS

Histologic margin status is the strongest predictor of progression for lentigo maligna melanoma. Patients with positive or close/<3 mm histologic margins should consider a re-excision due to the increased risk of relapse.

Understanding melanoma in situ: Lentigo maligna surgical treatment terminology and guideline adherence, a targeted review

BACKGROUND

Malignant melanoma in-situ, lentigo maligna (MMIS-LM) can be successfully treated with several different surgical techniques; however, the literature is inconsistent in defining them.

OBJECTIVE

To comprehensively define and describe the national guideline recommended surgical techniques used to treat MMIS-LM to help clarify and standardize this terminology to ensure compliance with the guidelines.

METHODS

A targeted literature review was performed from 1990 to 2022 focusing on articles that discussed the national guideline recommended surgical techniques of wide local excision, Mohs micrographic surgery (MMS), modified Mohs surgery, and staged excision/Slow-Mohs for MMIS-LM, as well as the related methods of tissue processing. National Comprehensive Cancer Network and American Academy of Dermatology guidelines were reviewed to identify how the techniques need to be employed to be compliant with guideline recommendations.

RESULTS

We describe the various surgical and tissue processing techniques and discuss advantages and disadvantages of each.

LIMITATIONS

This paper was styled as a narrative review defining and clarifying terminology and technique and does not investigate these topics more broadly.

CONCLUSION

Understanding the methodology and terminology for these surgical procedures and tissue processing methods is critical so that both general dermatologists and surgeons can employ these techniques effectively for optimal patient care.

Topical and Intralesional Immunotherapy for Melanoma In Situ: A Review

The incidence of in situ melanoma (MIS) has increased over the last decades. The mainstay of treatment for MIS, including lentigo maligna (LM), is complete surgical excision with clear margins (0.5 to 1.0 cm). Nevertheless, MIS lesions often affect elderly patients with comorbidities and involve large lesions in cosmetically sensitive areas, which means surgery is not always appropriate. Non-surgical treatments have a role in these cases, and include radiotherapy, cryosurgery, immunotherapy, laser therapy, and other topical medications. This study aims to review the applications of immunotherapy in MIS, either in monotherapy or in combination with other therapeutic alternatives. The main forms of immunotherapy used are imiquimod and, to a lesser extent, intralesional interferon-α (IL-INF-α) and ingenol mebutate (IM). IL-INF-α and IM have not been studied as extensively as imiquimod, whose results in real-life practice are encouraging. The clearance and recurrence rates reported in MIS treated with imiquimod as monotherapy, or as an adjuvant after surgery with affected or narrow margins, make imiquimod a reliable therapeutic alternative in selected cases. Also, its use as a neoadjuvant therapy before surgery was shown to reduce the final surgical defect size required to confirm negative histologic margins. In conclusion, local immunotherapy is frequently used in clinical practice and experience confirms it to be an excellent option for certain patients.

Outcomes of invasive melanoma of the head and neck treated with Mohs micrographic surgery - A multicenter study

BACKGROUND

There are no randomized controlled trials to guide surgical margins for invasive head and neck (H&N) melanoma using conventional excision. Mohs micrographic surgery (MMS) has shown improved local recurrence rates and survival for invasive H&N melanomas.

OBJECTIVE

Determine local recurrence (LR), nodal recurrence, and distant recurrence rates, and disease specific survival for invasive melanoma of the H&N treated with MMS.

METHODS

A retrospective multicenter study of 785 cases of invasive H&N melanoma treated with MMS using frozen sections with melanoma antigen recognized by T-cells 1 immunohistochemical staining was performed to evaluate long-term outcomes over 12-years.

RESULTS

785 melanomas (thickness: 0.3 mm-8.5 mm) were treated with MMS. LR, nodal recurrence, and distant recurrence rates were 0.51% (4/785), 1.0% (8/785), and 1.1% (9/785) respectively. For T1, T2, T3, and T4 tumors LR was 0.16% (1/636), 1.18% (1/85), 2.22% (1/45), and 5.26% (1/19), respectively. Five and 10-year disease specific survival were 96.8% (95% CI 95.0% to 98.5%) and 93.4% (95% CI 88.5% to 98.3%).

LIMITATIONS

A nonrandomized retrospective study.

CONCLUSION

MMS achieves significant improvements in LR compared to a meta-analysis of historical cohorts of patients treated with conventional excision. MMS should be considered an important surgical option for invasive H&N melanoma.

Previous therapy and the recurrence rate of basal cell carcinoma after Mohs surgery: a meta-analysis

Mohs micrographic surgery (MMS) for basal cell carcinoma (BCC) is indicated for patients at high risk of recurrence; other therapies, including standard surgical excision, cryotherapy, electrodesiccation and curettage, and radiotherapy, are used in low-risk BCC and in patients who cannot undergo surgery. However, in the case of recurrence following treatment with any of these methods, MMS is indicated. This study aimed to examine how preoperative treatment before MMS affects the recurrence rate after surgery. We conducted a meta-analysis to compare the recurrence rates of primary BCC and previously treated BCC in patients undergoing MMS, with a 5-year follow-up. The secondary outcomes were the recurrence rate after MMS based on previous radiation therapy status, mean time to recurrence, and number of cases undergoing more than one stage of MMS. The recurrence rate in the previously treated group was 2.44 times greater than that of the primary BCC group. In the previous treatment group, the patients who underwent previous radiation showed a 2.52-fold higher recurrence rate than those with no previous radiation therapy. However, there was no significant difference in the mean time to recurrence and the number of cases requiring MMS > 1 stage between the previously treated and non-treated groups. Patients with previously treated BCC, especially those treated using radiation, had a higher likelihood of recurrence.

What Should Be the Surgical Technique for Treating Thin Melanoma?

Surgical Technique for Treating Thin MelanomaProspective data comparing the safety and efficacy of complete margin assessment and conventional wide excision in the treatment of melanoma are lacking. This article reviews the evidence and proposes a trial to determine which surgical method is better for treating thin invasive melanoma and melanoma in situ in high-risk anatomical locations.

Factors Influencing General Dermatologists When Referring Patients With Head and Neck Melanoma for Mohs Micrographic Surgery: A Nationwide Cross-Sectional Survey

BACKGROUND

Mohs micrographic surgery (MMS) for cutaneous melanoma has demonstrated higher cure rates, lower local recurrence rates, and improved survival compared with wide local excision (WLE). However, factors affecting referrals by general dermatologists for MMS of head and neck melanoma (HNM) are unknown.

OBJECTIVE

To elucidate referral factors and treatment perspectives of general dermatologists regarding MMS for melanoma in situ (MIS)/lentigo maligna (LM) and early-stage melanoma on the head and neck.

MATERIALS AND METHODS

A cross-sectional analysis was performed using survey responses of general dermatologists with membership in the American Academy of Dermatology.

RESULTS

A total of 231 and 132 of the 402 responding general dermatologists routinely referred melanoma in situ MIS/LM and early invasive melanoma for MMS, respectively. Lack of local access to a Mohs surgeon was the most common deterring reason for MIS/LM referral to MMS, whereas the preference for WLE was the most common deterring reason for early invasive melanoma.

CONCLUSION

Lack of local access to a Mohs surgeon treating HNM with MMS is the primary barrier in referrals to Mohs surgeons for MIS and LM. Among general dermatologists, WLE is preferred for early invasive HNM.

A Cost Comparison Between Mohs Micrographic Surgery and Conventional Excision for the Treatment of Head and Neck Melanomas In Situ and Thin Melanomas

BACKGROUND

Variation in operative setting and surgical technique exists when treating specialty site melanomas. There are limited data comparing costs among surgical modalities.

OBJECTIVE

To evaluate the costs of head and neck melanoma surgery performed with Mohs micrographic surgery or conventional excision in the operating room or office-based settings.

METHODS

A retrospective cohort study was performed on patients aged 18 years and older with surgically treated head and neck melanoma in 2 cohorts, an institutional cohort and an insurance claims cohort, for the years 2008-2019. The primary outcome was total cost of care for a surgical encounter, provided in the form of insurance reimbursement data. A generalized linear model was used to adjust for covariates affecting differences between treatment groups.

RESULTS

In the institutional and insurance claims cohorts, average adjusted treatment cost was highest in the conventional excision-operating room treatment group, followed by the Mohs surgery and conventional excision-office setting (p < .001).

CONCLUSION

These data demonstrate the important economic role the office-based setting has for head and neck melanoma surgery. This study allows cutaneous oncologic surgeons to better understand the costs of care involved in head and neck melanoma treatment. Cost awareness is important for shared decision-making discussions with patients.

Local Recurrence Rates of Malignant Melanoma After Mohs Micrographic Surgery Are Lowest With 5- to 10-mm Initial Margins: A Systematic Review and Meta-Analysis

BACKGROUND

Current consensus guidelines have discouraged the use of sub-0.5-cm (in situ) and sub-1-cm (invasive) margins when performing Mohs micrographic surgery (Mohs) for melanoma, with minimal evidence to guide this recommendation.

OBJECTIVE

To compare melanoma local recurrence rates after Mohs based on initial margin size.

MATERIALS AND METHODS

A systematic review and meta-analysis was conducted with search terms including Mohs micrographic surgery, surgical margin, recurrent disease, and melanoma.

RESULTS

Forty-three studies were included. The 5- to 10-mm margin category had a statistically significant lower local recurrence compared with 1- to 5-mm and 5-mm categories. Recurrence for 1- to 5-mm, 5-mm, 5- to 10-mm, and 10-mm categories were 2.3% (CI 0.8-3.5, p < .001), 1.4% (CI 0.6-2.2, p < .001), 0.3% (CI 0.2-0.5, p < .001), and 6.1% (CI -6.7 - 18.8, p = .349), respectively. Number of stages for 1 to 5, 5, 5 to 10, and 10-mm categories were 1.8, 1.8, 1.6, and 1.6, respectively. There was no statistically significant difference between the groups (p = .694).

CONCLUSION

Five- to 10-mm margins were associated with the lowest local recurrence rates. A 5- to 10-mm initial margin should be considered where other factors (tumor characteristics, anatomical or functional considerations) allow.

Staged Excision of Lentigo Maligna of the Head and Neck: Assessing Surgical Excision Margins With Melan A, SOX10, and PRAME Immunohistochemistry

BACKGROUND

Staged excision has emerged as a superior treatment option for lentigo maligna (LM) of the head and neck when compared with conventional wide local excision. Assessing surgical excision margins for remaining LM poses a diagnostic challenge.

OBJECTIVES

To determine whether immunohistochemical (IHC) staining with SOX10 and preferentially expressed antigen in melanoma (PRAME) aids in diagnosing LM on excision margins compared with conventional hematoxylin and eosin and Melan A IHC staining.

METHODS

This study included cases of LM of the head and neck treated with staged excision. Histological findings were reviewed according to standard criteria for the diagnosis of LM and compared with the results after IHC staining for Melan A, SOX10, and PRAME.

RESULTS

The cohort consisted of 35 sections. Based on hematoxylin and eosin and Melan A IHC staining, 23 sections were diagnosed as LM by the initial pathologist. Further staining with SOX10 IHC showed only 8 to be consistent with a diagnosis of LM and 9 revealing features of actinic melanocyte hyperplasia. PRAME was positive in 5 of the 8 cases of LM and negative in all 9 cases of actinic melanocyte hyperplasia (P = 0.009). The presence of melanocyte nests (P = 0.29) and pagetoid spread (P = 0.003) was the most reliable histological findings distinguishing LM from its mimics.

CONCLUSION

SOX10 is a more specific and sensitive marker for melanocytes when assessing for LM on excision margins compared with Melan A. The addition of PRAME can be useful to confirm or exclude the diagnosis in challenging cases.

Wide Local Excision with Sentinel Lymph Node Biopsy for Digital Papillary Adenocarcinoma: A Case Report

Digital papillary adenocarcinoma (DPA) is a rare but locally aggressive eccrine tumour that has metastatic potential and most frequently found in the upper extremity. It usually presents as an unremarkable swelling of the skin, commonly misdiagnosed as a benign lesion. We present a 67-year-old male who presented with a slowly growing mass of the right middle finger that was biopsied and diagnosed with DPA. The patient was treated with wide local excision (WLE) and sentinel lymph node biopsy by us during the same operative encounter. This report highlights the need for increased clinical vigilance to diagnose DPAs, and that WLE and sentinel lymph node biopsies can be safe and effective treatments offered. Level of Evidence: Level V (Therapeutic).

Lentigo Maligna of the head and neck: A retrospective study assessing surgical excision margins in a South African population

Background

Lentigo maligna (LM) is a subtype of melanoma in situ that occurs on sun-damaged skin and is associated with significant subclinical extension beyond the clinical margins of the lesion.

Objectives

This study aimed to determine if the standard recommended tumor excision margins for LM are adequate to achieve a 97% clearance rate and if any patient or tumor characteristics warranted wider margins.

Methods

This study is a retrospective chart review of all patients who were diagnosed with LM of the head and neck and treated with staged excision.

Results

The study included 64 patients. With a 6 mm surgical excision margin, only 60.9% of LM were completely excised. A 9 mm margin resulted in complete clearance of 71.9% of LM cases, and a 12 mm margin resulted in complete clearance in 90.6%. A surgical excision margin of 18 mm would have been required to excise 96.7% of tumors completely. Recurrent tumors (P = .01) and tumor size larger than 20 mm were associated with wider surgical excision margins (P = .154).

Conclusion

This study of LM in a South African population corroborates that the standard surgical excision margins recommended by international melanoma guidelines for LM are inadequate to achieve a 97% clearance rate.

A review of Mohs Micrographic Surgery for skin cancer: Part 1 - melanoma and rare skin cancers

Mohs micrographic surgery is a precise and effective method commonly used to treat high risk basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) on the head and neck. Whilst the majority of evidence for Mohs relates to keratinocyte cancers, there is published evidence for other types of skin cancer. This review aims to discuss the evidence for using MMS to treat six different types of skin cancer, including melanoma, lentigo maligna, dermatofibrosarcoma protuberans, atypical fibroxanthoma, microcystic adnexal carcinoma and pleomorphic dermal sarcoma, particularly in the context of survival rates and cancer recurrence. These cancers were chosen as there was sufficient literature for inclusion and given MMS is most useful when cancers are contiguous, rather than for cancers with marked metastatic potential such as angiosarcoma or merkel cell carcinoma. We searched Medline, Pubmed and Embase using the keywords: 'melanoma', 'mohs micrographic surgery', 'lentigo maligna', 'dermatofibrosarcoma protuberans', 'atypical fibroxanthoma', 'microcystic adnexal carcinoma' and 'pleomorphic dermal sarcoma' along with their appropriate synonyms, to identify the relevant English-language articles from the year 2000 onwards given that literature for Mohs on non-keratinocyte is sparse prior to this date. A MeaSurement Tool to Assess systematic Reviews (AMSTAR) was used to assess the validity of systematic reviews. Further high-quality, multi-centre randomised trials are necessary to establish the indications and efficacy of MMS for rarer cancers, particularly for AFX and PDS, where limited studies were identified.

Systematic Review of Technical Variations for Mohs Micrographic Surgery for Melanoma

BACKGROUND

Mohs micrographic surgery (MMS) for cutaneous melanoma is becoming more prevalent, but surgical technique varies.

OBJECTIVE

To define variations in published techniques for MMS for melanoma.

METHODS AND MATERIALS

A systematic review was performed of PubMed, EMBASE, and Scopus databases to identify all articles describing surgical techniques for MMS for melanoma. Technical details were recorded for the preoperative, intraoperative, and postoperative phases of MMS.

RESULTS

Twenty-four articles were included. Mohs surgeons vary in how they assess clinical margins, how wide a margin they excise on the first MMS layer, and how they process tissue to determine tumor stage and margin clearance during MMS for melanoma.

CONCLUSION

Mohs micrographic surgery for melanoma is performed with varied surgical techniques. To establish best practices, additional research is necessary to determine how different techniques affect outcomes.

Clinical and histologic features associated with lentigo maligna clearance after imiquimod treatment

BACKGROUND

Imiquimod cream may be used as a non-surgical treatment for lentigo maligna or as adjuvant therapy following excision to decrease the risk of recurrence.

OBJECTIVES

To evaluate histologic and clinical factors associated with clinical clearance of lentigo maligna treated with imiquimod.

METHODS

We performed a retrospective review of all patients diagnosed with lentigo maligna and treated with imiquimod between 1997 and 2019 at our academic institution.

RESULTS

We observed clinical clearance in 93% (66/71) of participants who received adjuvant imiquimod following surgery and 79% (19/24) in the primary non-surgical treatment group over a median of 38 months of follow-up. In the adjuvant therapy group, positive surgical margins were associated with a decreased rate of clinical clearance when compared to cases with close (<1 mm) margins or background melanocytic dysplasia (83.3 vs. 100%, p = .01). The presence of an inflammatory response during treatment was associated with increased clearance (94.1 vs. 66.7%, p = .02).

CONCLUSIONS

Adjuvant imiquimod treatment may decrease LM recurrence rates in cases with background melanocytic dysplasia or close margins. LM cases with positive surgical margins need close clinical follow-up given higher recurrence rates.