Upstaging of melanoma in situ and lentigo maligna treated with Mohs micrographic surgery rarely results in additional surgical management

Mohs micrographic surgery in the surgical treatment paradigm of melanoma in situ and invasive melanoma: A clinical review of treatment efficacy and ongoing controversies

Mohs Micrographic Surgery (MMS) for treatment of melanoma offers several advantages over wide local excision (WLE), including complete histologic margin evaluation, same-day resection and closure, and sparing of healthy tissue in critical anatomic sites. Recently, a large volume of clinical data demonstrating efficacy in MMS treatment of melanoma was published, leading to emerging patient safety considerations of incurred treatment costs, risk of tumor upstaging, and failure of care coordination for sentinel lymph node biopsy (SLNB). MMS offers a safe, effective, and value-based treatment for both melanoma in situ (MIS) and invasive melanoma (IM), particularly with immunohistochemistry use on frozen sections. Compared to wide local excision, MMS treatment demonstrates similar or improved outcomes for local tumor recurrence, melanoma-specific survival, and overall survival at long-term follow-up. Tumor upstaging risk is low, and if present, alteration to clinical management is minimal. Discussion of SLNB for eligible head and neck IM cases should be done prior to MMS. Though challenging, successful multidisciplinary coordination of SLNB with MMS has been demonstrated. Herein, we provide a detailed clinical review of evidence for MMS treatment of cutaneous melanoma and offer recommendations to address current controversies surrounding the evolving paradigm of surgical management for both MIS and invasive melanoma (IM).

Risk factors associated with tumor upstaging in melanomas treated with Mohs micrographic surgery with melanocytic immunohistochemistry

Background

Mohs micrographic surgery with melanocytic immunohistochemistry (MMS-I) is increasingly utilized for special site melanoma treatment. Yet, frequency and risk factors associated with upstaging of all-stage cutaneous melanomas treated with MMS-I remain undefined.

Objective

Determine upstaging frequency and factors associated with tumor upstaging for all-stage melanomas treated with MMS-I.

Methods

In this retrospective, single-center case series, all cases of invasive and in situ melanoma treated with MMS-I between 2008 and 2018 were reviewed. Patient and tumor characteristics were recorded and compared between tumors that were and were not upstaged from their initial T stage.

Results

Of the 962 melanoma MMS-I cases identified, 44 (4.6%) were upstaged, including 5.6% of in situ and 2.5% of invasive tumors. Risk factors for upstaging included lack of excisional intent at the time of initial biopsy (P < .01), nonlentigo maligna subtype (P = .03), female sex (P = .02), and initial in situ diagnosis (P = .03). Nonstatistically significant characteristics evaluated included patient age (P = .97), initial Breslow depth (P = .18), and biopsy type (P = .24).

Limitations

Retrospective study design.

Conclusions

All-stage cutaneous melanomas treated with MMS-I are associated with low upstaging rates. Tumor upstaging is associated with lack of excisional intent, female sex, and in situ tumors.

Pathologic Upstaging of Cutaneous Melanoma After Mohs Micrographic Surgery

BACKGROUND

Mohs micrographic surgery (MMS) is used for melanoma in situ (MIS) and thin invasive melanomas, particularly on the head and neck, during which a debulk section is typically prepared. Tumor upstaging occurs if the debulking specimen meets criteria for an increased tumor (T) stage per the American Joint Committee on Cancer 8th edition compared with the initial biopsy. Upstaging can alter survival and recurrence outcomes, resulting in increased patient morbidity and mortality.

OBJECTIVE

To determine the rate of cutaneous melanoma upstaging during MMS.

MATERIALS AND METHODS

A multicenter study was performed. Information from electronic medical records from 3 dermatologic surgeons performing MMS for cutaneous melanoma were logged from January 1, 2017 to December 31, 2021. Deidentified information regarding patient demographics and tumor characteristics was recorded.

RESULTS

Three-hundred and ten cases of cutaneous melanoma treated with MMS were identified. 2.3% of cases were upstaged, ranging from T1a to T3a. No significant risk factors for upstaging were identified.

CONCLUSION

Our data demonstrate a lower rate of cutaneous melanoma upstaging during MMS than the current literature. Differences may be accounted for because of differing patient populations, cutaneous melanoma detection at an earlier clinical stage, and evolving melanoma histologic criteria.

Clinical findings are not helpful in detecting lentigo maligna melanoma in patients with biopsy-proven lentigo maligna

BACKGROUND

Lentigo maligna (LM) based on biopsy material might be lentigo maligna melanoma (LMM) after excision.

OBJECTIVES

Investigate whether clinical and dermoscopic mapping increases the detection rate of LMM when investigating staged excision specimens of biopsy proven LM.

METHODS

Patients with biopsy-proven LM planned for staged excision were included. Using clinical inspection and dermoscopy, spots suspicious for LMM were marked. After the excision, needles were placed at the marked spots. Histological examination using vertical sections was done at the needles followed by the standard amount of vertical sections.

RESULTS

In 28 of the 58 biopsy-proven LM, there was clinical suspicion of LMM, only 3 of these 28 cases were upgraded into LMM. These three cases showed LMM in other sections, whereas only 1 case showed LMM around the needle. Within the group without clinical suspicion of LMM, 2 cases were LMM. Biopsy-proven LM were in fact LMM in 8.6% of the cases and were found without the clinical guidance of the dermatologist.

CONCLUSIONS

8.6% of the biopsy-proven LM were LMM after complete histological examination. In this study, the dermatologist was not able to increase the detection rate of LMM by using clinical and dermoscopic mapping.

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.