Rapid Immunostaining in Mohs: Current Applications and Attitudes

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.

Lentigo Maligna Treatment-An Update

Lentigo maligna (LM) is a melanoma in situ that is prevalent in chronically sun-damaged skin. Characterized by a slow growth pattern and high mutation rates due to chronic UV exposure, LM poses diagnostic and therapeutic challenges, particularly given its tendency to mimic other skin lesions and its occurrence in cosmetically sensitive areas. Its diagnosis is based on an integrated approach using dermoscopy and reflectance confocal microscopy (RCM). Despite its slow progression, LM can evolve into lentigo maligna melanoma (LMM), making its treatment necessary. Treatment modalities encompass both surgical and non-surgical methods. Surgical treatments like Wide Local Excision (WLE) and Mohs Micrographic Surgery (MMS) aim for clear histological margins. WLE, a standard melanoma surgery, faces challenges from LM's subclinical extensions, which increase the recurrence risk. MMS, effective for large or poorly defined lesions, is defined by precise margin control while considering cosmetic outcomes. Non-surgical options, including radiotherapy and imiquimod, are alternatives for non-surgical candidates. Radiotherapy has been effective since the 1950s, offering good control and cosmetic results, especially for older patients. Imiquimod, an immunomodulator, shows promise in treating LM, though its application remains off-label. The increasing incidence of LM/LMM necessitates a balance in treatment choices to minimize recurrence and maintain cosmetic integrity. A multidisciplinary approach, integrating clinical examination with dermoscopy and RCM and histological assessment, is essential for accurate diagnosis and effective LM management.

Recurrence Rate for Melanoma Excised by Mohs Micrographic Surgery Without Immunostaining

BACKGROUND

Mohs micrographic surgery (MMS) is becoming increasingly popular for the treatment of cutaneous melanoma (CM) as multiple studies have demonstrated favorable outcomes for local recurrence and overall survival.

OBJECTIVE

To analyze the outcomes of noninvasive (NIM) and invasive melanomas (IM) using MMS with fresh frozen sections. The primary outcome was local recurrence. The secondary outcome was to identify mean surgical margins based on tumor type and location.

METHODS

Retrospective cohort study of 224 cases of CM treated from 2006 to 2016 at a tertiary academic center with MMS and fresh frozen sections by a single Mohs surgeon.

RESULTS

The overall recurrence rate was 2.6% with a mean follow-up of 36.2 months. The recurrence rate for NIM versus IM was 1.6% and 7%, respectively. The mean margins for NIM and IM were 7.9 mm and 10.1 mm, respectively. These varied by tumor site and location.

CONCLUSION

This study supports the use of MMS in the treatment of CM and highlights how narrower surgical margins for NIM of the head and neck can be achieved without increasing risk of local recurrence.

MOC-31 Antibody Immunolabeling During Mohs Surgery

BACKGROUND

Ber-EP4 is an antibody that labels basal cell carcinoma (BCC) by targeting epithelial cell adhesion molecule (Ep-CAM). MOC-31, a monoclonal mouse antibody, also targets Ep-CAM and is currently used to differentiate several extracutaneous epithelial tumors. However, the utility of MOC-31 has not been fully described in cutaneous tumors and in Mohs micrographic surgery (MMS).

OBJECTIVE

To evaluate MOC-31 labeling in BCC and other cutaneous tumors and to compare immunolabeling intensity of MOC-31 and Ber-EP4 in BCCs.

MATERIALS AND METHODS

Nineteen permanently fixed and 29 frozen BCC specimens and 23 other cutaneous tumors were labeled with MOC-31; labeling intensity of tumors, epidermis, and adnexal structures were recorded. In a separate study, a blinded dermatopathologist compared labeling intensities of 8 BCC specimens, each labeled with MOC-31 and Ber-EP4.4.

RESULTS

MOC-31 labeled all BCCs. Eccrine coils and follicular bulbs did label variably, although this did not detract utility of MOC-31. Five of thirteen cutaneous squamous cell carcinomas and one of two Merkel cell carcinomas demonstrated MOC-31 positivity. MOC-31 and Ber-EP4 labeled BCCs similarly.

CONCLUSION

MOC-31, an antibody directed against Ep-CAM, is sensitive for BCCs in frozen specimens encountered in MMS and permanently fixed specimen. In addition, MOC-31 demonstrated comparable immunolabeling characteristics with Ber-EP4 for BCCs.

Immunostained Frozen Sections Vs Traditional Permanent Paraffin Sections for Lentigo Maligna Treated With Mohs Micrographic Surgery

BACKGROUND

Mohs micrographic surgery (MMS) has risen in popularity as a management option for treating lentigo maligna (LM) because of its ability to accurately detect subclinical spread while conserving tissue. The primary concern for opponents of MMS in melanoma remains the difficulty associated with interpretation of frozen sections compared with traditional paraffin sections; this has been made easier with the advent of immunostaining.

OBJECTIVE

Our study aims to assess the concordance in clearance reporting of LM in immunostained frozen sections compared with permanent paraffin sections and hematoxylin and eosin staining.

METHODS

We conducted a retrospective analysis of 38 LM cases treated by MMS between 2017 and 2020 in Melbourne, Australia. Immunostained frozen sections were assessed by a Mohs surgeon, whereas permanent paraffin sections were assessed by an external dermatopathologist.

RESULTS

We report 86% agreement in reporting of LM in immunostained frozen sections compared with permanent paraffin sections. In 5/38 cases, permanent paraffin sections were reported as clear for LM, but the Mohs surgeon had detected positive margins, requiring further excision.

CONCLUSION

For LM treated with MMS, there is a high agreement of clearance reporting between immunostained stained frozen sections and permanent paraffin sections without immunostaining; however, immunostained frozen sections may be more sensitive.

The Current State of Mohs Surgery for the Treatment of Melanoma: A Nationwide Cross-Sectional Survey of Mohs Surgeons

BACKGROUND

The increased use of Mohs micrographic surgery (MMS) to treat melanoma has been accompanied by wide variations in practice patterns and a lack of best practice guidelines.

OBJECTIVE

The present study was a nationwide cross-sectional survey of Mohs surgeons to elucidate commonalities and variations in their use of MMS to treat melanoma.

MATERIALS AND METHODS

A cross-sectional analysis was performed using survey responses of Mohs surgeons with membership in the American College of Mohs Surgery.

RESULTS

A total of 210/513 (40.9%) participants used MMS to treat melanoma of any subtype and 123/210 (58.6%) participants within this group treated invasive T1 melanoma (AJCC Eighth Edition) with MMS. A total of 172/210 (81.9%) participants debulked melanoma in situ (MIS). Average margin size of the first Mohs stage for MIS was 4.96 ± 1.74 mm. A total of 149/210 (71.0%) participants used immunohistochemical stains, with 145/149 (97.3%) using melanoma antigen recognized by T-cells 1 (MART-1) in 96.5% of melanoma cases treated with MMS.

CONCLUSION

Over half of surveyed Mohs surgeons treating melanoma with MMS are treating early invasive melanoma with MMS. Most Mohs surgeons treating melanoma with MMS debulk MIS and virtually all use MART-1 when excising invasive melanoma with MMS.

Mohs surgery for the treatment of lentigo maligna and lentigo maligna melanoma - a systematic review

BACKGROUND

The role of Mohs micrographic surgery (MMS) in the treatment of lentigo maligna (LM), and lentigo maligna melanoma (LMM) has been controversial. The use of frozen sections is commonly cited as a suboptimal way to distinguish atypical melanocytes, resulting in traditional wide-local excision techniques as the mainstay of therapy.

OBJECTIVE

To compare the success of MMS as a treatment option for LM and LMM with that of traditional surgical and nonsurgical therapies by analyzing the published recurrence rates of these lesions after MMS procedures.

METHODS AND MATERIALS

PubMed database was used to find relevant articles with search terms related to MMS, LM, and LMM.

RESULTS

The search strategy resulted in 27 articles that fulfilled the inclusion criteria. All studies considered; MMS provided a 1.35% recurrence rate with follow-up times ranging from 1 month to 5 years. Specifically, studies employing classical MMS and MMS with rush sections provided recurrence rates of 1.17% and 2.4%, respectively.

CONCLUSION

MMS is one of the most successful treatment options for LM and LMM, with published evidence of improved recurrence rates when compared to other forms of therapy. Additional clinical trials are needed to further delineate the role of MMS in the treatment algorithm for these conditions.

Mohs Micrographic Surgery: Past, Present, and Future

BACKGROUND

Mohs micrographic surgery (MMS) is a frequently used technique that provides total margin visualization for treatment of skin neoplasms.

OBJECTIVE

To provide a comprehensive review of MMS literature, focusing on its origins, evidence behind present-day uses of MMS, and future directions.

METHODS

A literature search was conducted using PubMed to identify articles pertaining to MMS.

RESULTS

The fresh frozen technique led to widespread use of MMS in the 1970s. One randomized controlled trial and several large prospective studies have demonstrated low recurrence rates for treatment of nonmelanoma skin cancer (NMSC). MMS, when compared with surgical excision, also achieved a statistically significant higher cure rate for treatment of recurrent NMSC. Studies have demonstrated low recurrence for the treatment of melanoma and melanoma in situ with MMS. MMS has also been shown to effectively treat several rare cutaneous neoplasms. The future of MMS is likely to include the adoption of noninvasive imaging, immunostaining, and digital technology.

CONCLUSION

Mohs micrographic surgery is an effective treatment modality for numerous cutaneous neoplasms. It has achieved statistically significant superiority to surgical excision for the treatment of recurrent and high-risk NMSC. The future is likely to see increased use of noninvasive imaging, immunostaining, and digital technology.

Current perspectives on Mohs micrographic surgery for melanoma

Mohs micrographic surgery (MMS), a specialized surgical excision technique used primarily in the treatment of skin cancers, is tissue sparing and provides optimal margin control through evaluation of 100% of both the peripheral and deep margin. The use of MMS for the treatment of malignant melanoma (MM) and melanoma in situ (MIS) has been slow in gaining the same widespread acceptance that it has for keratinocyte carcinomas despite its cost-effectiveness and the growing body of evidence demonstrating similar or improved cure rates to standard wide local excision. However, modern advances in immunohistochemical staining have continued to greatly enhance the ability of Mohs surgeons to interpret MMS frozen sections of melanoma specimens – the primary concern of most opponents of MMS for melanoma. These advances, coupled with an increased recognition by professional organizations of the utility of MMS in treating MM and MIS, have led to a rise in the use of MMS for melanoma in recent years. Given the expanding role of MMS in the treatment of cutaneous melanoma, this manuscript will describe how MMS is performed, discuss the rationale and current evidence regarding the use of MMS for MM and MIS, review the immunohistochemical stains currently available for use in MMS, and consider special situations and future directions in this area of growing interest.

High-risk squamous cell carcinoma masquerading as dense inflammation on Mohs frozen sections

High-risk squamous cell carcinoma (SCC) can present a unique challenge in Mohs surgery. This case report describes how high-risk SCC may masquerade as only a dense inflammation on frozen sections. This feature should raise the index of suspicion for hidden SCC and be a routine indication for further processing by paraffin sections and immunohistochemistry.

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.