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.

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.

Staged melanoma excision requires larger margins for tumor clearance and results in low rates of recurrence

There is controversy regarding the optimal surgical modality and ideal recommended margins for treating melanoma in situ (MIS) and invasive melanoma (IM). Although wide local excision is recommended, staged excision offers excellent margin control and low recurrence rates. In this manuscript, we reviewed a 10-year experience of staged excisions for the treatment of MIS and IM. A retrospective review was performed of 130 MIS and 32 IM cases treated with staged excision from April 2012 to April 2022. Staged excision was performed on the head and neck in 102 (79%) MIS and 23 (72%) IM cases. Approximately 10% of cases required surgical margins above the current recommendations (11 (9%) MIS and 6 (19%) IM). Twenty-three (19%) MIS and 7 (22%) IM cases required more than one excision to obtain clearance. Recurrence rates among MIS and IM were 0.0% and 0.6%, respectively. Upstaging occurred in 5 (4%) MIS and 7 (22%) IM cases. Complex repairs were performed on 82 (63%) MIS and 17 (53%) IM cases. Our findings revealed that staged excision provides effective margin control and low recurrence rates. Approximately 10% of patients required margins greater than the current recommendations, leading to larger defects and more complex repairs.

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%).

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

BACKGROUND

Prospective trials have not compared the local recurrence rates of different excision techniques for cutaneous melanomas on the head and neck.

OBJECTIVE

To determine local recurrence rates of cutaneous head and neck melanoma after wide local excision (WLE), Mohs micrographic surgery (MMS), or staged excision.

METHODS

A systematic review of PubMed, EMBASE, and Web of Science identified all English case series, cohort studies, and randomized controlled trials that reported local recurrence rates after surgery for cutaneous head and neck melanoma. A meta-analysis utilizing a random effects model calculated weighted local recurrence rates and confidence intervals (CI) for each surgical technique and for subgroups of MMS and staged excision.

RESULTS

Among 100 manuscripts with 13,998 head and neck cutaneous melanomas, 51.0% (7138) of melanomas were treated by WLE, 34.5% (4826) by MMS, and 14.5% (2034) by staged excision. Local recurrence rates were lowest for MMS (0.61%; 95% CI, 0.1%-1.4%), followed by staged excision (1.8%; 95% CI, 1.0%-2.9%) and WLE (7.8%; 95% CI, 6.4%-9.3%).

LIMITATIONS

Definitions of local recurrence varied. Surgical techniques included varying proportions of invasive melanomas. Studies had heterogeneity.

CONCLUSION

Systematic review and meta-analysis show lower local recurrence rates for cutaneous head and neck melanoma after treatment with MMS or staged excision compared to WLE.

Outcomes of Staged Excision With Circumferential en Face Margin Control for Lentigo Maligna of the Head and Neck

BACKGROUND

Treatment practices vary for lentigo maligna (LM). Staged excision with circumferential margin control (SECMC) has the potential to achieve low recurrence rates.

OBJECTIVES

To evaluate the clinical outcomes of SECMC using permanent, paraffin-embedded sections and delayed reconstruction.

METHODS

We conducted a retrospective, uncontrolled, observational cohort study involving patients who underwent staged excision for LM of the head and neck at Women's College Hospital in Toronto, Canada, from September 2010 to March 2013. Recurrence and infection rates were ascertained from patient charts and postal surveys.

RESULTS

One hundred and two patients (45 female, 57 male) were included with a median follow-up time of 1410.5 (IQR 260-1756) days. The median age was 69 (IQR 61-79) years. Approximately one-fifth (21%, 21/102) of patients required greater than 0.5 cm margins to achieve histological clearance. One patient (1/102) upstaged to invasive melanoma based on the initial stage of excision. The infection rate was 6% (6/102) and the 5-year cumulative recurrence rate was 1.4% (95% CI 0.2-9.6%).

CONCLUSION

SECMC using permanent sections and delayed reconstruction appears to be a safe and effective treatment method for LM on the head and neck. Randomized trials are needed to help define the optimal treatment.

Long-term outcomes of Mohs micrographic surgery for invasive melanoma of the trunk and proximal portion of the extremities

BACKGROUND

Microscopic evaluation of the entire surgical margin during excision of cutaneous malignancies results in the highest rates of complete excision and lowest rates of true local scar recurrence. Few studies demonstrate the outcomes of Mohs micrographic surgery specifically for invasive melanoma of the trunk and proximal portion of the extremities.

OBJECTIVE

To evaluate the long-term efficacy of Mohs micrographic surgery for invasive melanoma of the trunk and proximal portion of the extremities, including true local scar recurrence rate, distant recurrence-free survival, and disease-specific survival.

METHODS

Prospectively collected study of 1416 cases of invasive melanoma of the trunk and proximal portion of the extremities was performed to evaluate long-term outcomes.

RESULTS

True local scar recurrences occurred in our cohort at a rate of 0.14% (2/1416), after a mean follow-up period of 75 months and were not associated with tumor depth. The rate of satellite/in-transit recurrences and the disease-specific survival stratified by tumor thickness were superior to historical control values.

LIMITATIONS

We used a nonrandomized, single institution, retrospective design.

CONCLUSIONS

Mohs micrographic surgery of primary cutaneous invasive melanoma on the trunk and proximal portion of the extremities resulted in local control of 99.86% of tumors and an overall disease-specific death rate superior to that of wide local excision.

Histologic Features Associated With an Invasive Component in Lentigo Maligna Lesions

Importance

Lentigo maligna (LM) presents an invasive component in up to 20% of biopsied cases, but to date the histologic features useful in detecting this invasive component have not been described. Some histologic characteristics are hypothesized to contribute to the progression of LM invasion.

Objective

To identify the histologic characteristics associated with lentigo maligna melanoma (LMM) in patients with LM diagnosed by a partial diagnostic biopsy.

Design, Setting, and Participants

A retrospective cross-sectional study of patients treated between January 1, 2000, and December 31, 2017, was conducted in a referral oncology center in València, Spain. Data and specimens of patients (n = 96) with a diagnosis of primary cutaneous melanoma in the form of either LM or LMM who had undergone surgical treatment, a complete histologic examination of the whole tumor, and an initial diagnostic partial biopsy of LM were included in the study. Histologic assessment was blinded to the presence of an invasive component.

Interventions

All biopsy specimens were evaluated for the presence of certain histologic characteristics.

Main Outcomes and Measures

Comparisons between invasive samples and samples without an invasive component were performed. The differences in the distribution of variables between the groups were assessed using the χ2 and Fisher exact tests, and the degree of association of the relevant variables was quantified by logistic regression models. A classification and regression tree analysis was performed to rank the variables by importance.

Results

In total, 96 patients had sufficient histologic material that could be evaluated. The patients were predominantly male (56 [58.3%]) and had a mean (SD) age at diagnosis of 72 (12) years. Of these patients, 63 (65.6%) had an LM diagnosis and 33 (34.4%) had an LMM diagnosis (an invasive component). The histologic variables associated with the presence of an invasive component were melanocytes forming rows (odds ratio [OR], 11.5; 95% CI, 1.4-94.1; P = .02), subepidermal clefts (OR, 2.8; 95% CI, 1.0-7.9; P = .049), nests (OR, 3.0; 95% CI, 1.1-8.6; P = .04), and a lesser degree of solar elastosis (OR, 0.4; 95% CI, 0.1-1.1; P = .07). A classification and regression tree analysis of the relevant histologic features was able to accurately identify lentigo maligna with an invasive component (LMM) in more than 60% of patients.

Conclusions and Relevance

These findings may be useful in classifying early LM specimens at higher risk of invasion, which may eventually be relevant in identifying the most appropriate management for LM.

Locally Recurrent Lentigo Maligna and Lentigo Maligna Melanoma: Characteristics and Time to Recurrence After Surgery

BACKGROUND

Various studies have reported local recurrence (LR) rates after surgical treatment of lentigo maligna (LM) and lentigo maligna melanoma (LMM). However, the time to LR of LM/LMM is not currently known, as few studies report time to LR and have long-term follow-up.

OBJECTIVE

To define time to LR in LM/LMM after surgical treatment, and to describe features of observed LR.

MATERIALS AND METHODS

Retrospective single-center study of consecutive patients presenting with locally recurrent LM/LMM.

RESULTS

Six hundred forty-nine cases of LM/LMM were reviewed; 29 (21 LM, and 8 LMM) of 41 locally recurrent cases had original histology reports and were included. The mean time to LR was 57.5 months (range 7-194). For cases presenting as primary LM, LR was also in situ in 14/21 (67%) of cases. Seven of 21 LM recurred as LMM. Of the 8 primary LMM, 3/8 (37.5%) presented with subsequent LMM and all were slightly deeper on re-excision.

CONCLUSION

The mean time to LR of LM/LMM is at least 57.5 months, underscoring the importance of long-term follow-up. Seven of 21 LM recurred as invasive disease, but the lack of development of LMM from LM in most recurrent cases confirms LM is slowly progressive.

Recurrence Rate of Melanoma in Situ when Treated with Serial Disk Staged Excision: A Case Series

Background

Cutaneous melanoma is one of the fastest rising cancer diagnoses in recent years. Melanoma in situ (MIS) constitutes a large proportion of all diagnosed melanomas. While surgical excision is considered the standard of therapy, the literature is not clear on which surgical technique minimizes local recurrence. A common technique is serial staged excision (SSE), in which a series of mapped excisions are made according to histopathological examination of tissue. Previously published recurrence rates for SSE ranges from 0–12%, over a range of 4.7–97 months of mean follow-up.

Objective

To investigate the recurrence rate of MIS when excised using a serial disk staged excision technique with tissue marked at 12 O’clock for mapping, rush permanent processing and histologic examination, 3-suture tagging for subsequent stages, and “breadloafing” microscopic analysis. Additionally, to determine the relationship between initial lesion size and subsequent stages of excision required for clearance, and final surgical margin.

Methods

Single-institution retrospective chart review of 29 biopsy confirmed MIS lesions treated with our variant of SSE. Statistical analysis via independent t-tests.

Results

No recurrences were observed with mean follow-up of 31.5 months (SD 13.9), over range of 12–58 months. Mean surgical margin of 13.1 mm (SD 5.9). A trend towards larger surgical margin was seen with increasing pre-operative lesion size.

Conclusion

This method of SSE for treatment of MIS is comparable in efficacy to other SSE techniques, and may offer physicians a relatively simple, efficacious, and accessible alternative to wide local excision and Mohs micrographic surgery.

Diagnosis and management of lentigo maligna: a review

Lentigo maligna is a melanocytic neoplasm occurring on sun-exposed skin, usually on the head and neck, of middle-aged and elderly patients. It is thought to represent the in situ phase of lentigo maligna melanoma. The ill-defined nature and potentially large size of lesions can pose significant diagnostic and treatment challenges. The goal of therapy is to cure the lesions in order to prevent development of invasive disease, and surgical excision is the treatment of choice to achieve clear histological margins. Nonsurgical treatment modalities have been reported; however, evidence is lacking to support their use. Age, general health, and comorbidities need to be taken into account when deciding the right treatment modality for each individual patient.