Incomplete Excision Rate for Lentigo Maligna and Associated Risk Factors.

Standard treatment for lentigo maligna (LM) is surgical excision, yet insights into the frequency of and risk factors for incomplete excisions remain limited. The primary objectives were to assess the incomplete excision rate (IER) in primary LM and to explore potential risk factors for incomplete excisions. A retrospective analysis was conducted encompassing consecutive histopathologically confirmed LMs from 2014-2020. Descriptive statistics were used for LM characteristics and IER, while uni- and multivariate analyses were used for calculating risk factors. The study included 395 LMs with an IER of 16.7% (n = 66). Risk factors for higher incomplete excision rates included: head and neck lesions (p = 0.0014), clinical excision margins < 5 mm (p = 0.040), and utilization of preoperative partial biopsies (p = 0.023). Plastic surgeons had higher IERs than dermatologists (p = 0.036). Lesion diameter (p = 0.20) and surgeon experience (p = 0.20) showed no associations with incomplete excisions, yet LMs with a diameter ≥ 20 mm exhibited higher incomplete excision rates (23.2%) compared witho those < 10 mm (12.9%). LMs should be excised with at least 5-mm clinical margins, especially in the head and neck area. LMs ≥ 20 mm may be more surgically challenging. High-er incomplete excision rates associated with the use of preoperative biopsies and/or plastic surgeons may reflect challenging anatomical locations, larger lesion diameter, and/or ill-defined borders.

Utilizing deep learning model for assessing melanocytic density in resection margins of lentigo maligna.

BACKGROUND: Surgical excision with clear histopathological margins is the preferred treatment to prevent progression of lentigo maligna (LM) to invasive melanoma. However, the assessment of resection margins on sun-damaged skin is challenging. We developed a deep learning model for detection of melanocytes in resection margins of LM. METHODS: In total, 353 whole slide images (WSIs) were included. 295 WSIs were used for training and 58 for validation and testing. The algorithm was trained with 3,973 manual pixel-wise annotations. The AI analyses were compared to those of three blinded dermatopathologists and two pathology residents, who performed their evaluations without AI and AI-assisted. Immunohistochemistry (SOX10) served as the reference standard. We used a dichotomized cutoff for low and high risk of recurrence (≤ 25 melanocytes in an area of 0.5 mm for low risk and > 25 for high risk). RESULTS: The AI model achieved an area under the receiver operating characteristic curve (AUC) of 0.84 in discriminating margins with low and high recurrence risk. In comparison, the AUC for dermatopathologists ranged from 0.72 to 0.90 and for the residents in pathology, 0.68 to 0.80. Additionally, with aid of the AI model the performance of two pathologists significantly improved. CONCLUSIONS: The deep learning showed notable accuracy in detecting resection margins of LM with a high versus low risk of recurrence. Furthermore, the use of AI improved the performance of 2/5 pathologists. This automated tool could aid pathologists in the assessment or pre-screening of LM margins.

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.

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.

Sentinel lymph node biopsy for lentigo maligna melanoma under local anaesthesia.

BACKGROUND: Lentigo maligna melanoma is mainly localized in the head and neck region in elderly patients. Due to its slow horizontal growth, it has a good prognosis compared to other melanoma subtypes, but specific data are rare. OBJECTIVES: The aim of this study was to investigate sentinel lymph node biopsy in lentigo maligna melanoma under local anaesthesia and to discuss the benefit. METHODS: Investigation of patients with lentigo maligna melanoma and tumour thickness ≥1 mm treated at the Department of Dermatology, University Medical Centre Tuebingen, between January 2008 and October 2019. RESULTS: In total, 204 patients (126 SLNB, 78 non-SLNB) with a median age of 75.7 years (SLNB: 73.3 years, non-SLNB: 79.7 years) could be included. Sixteen of 126 (12.7%) sentinel lymph nodes were positive. Five-year overall survival was 87.9% (88.5% SLNB; 87.4% non-SLNB) and 5-year distant metastasis-free survival was 85.8% (85.4% SLNB; 86.7% non-SLNB). There was no significant difference for distant metastasis-free survival (p = 0.861) and overall survival (p = 0.247) between patients with and without sentinel lymph node biopsy. CONCLUSIONS: Sentinel lymph node biopsy in lentigo maligna melanoma under local anaesthesia is a safe and simple method, even in very old patients. However, LMM has a very good 5-year overall survival. In high-risk patients with high tumour thickness and/or ulceration, adjuvant immunotherapy can now be offered without the need to perform this procedure.

Is sentinel lymph node biopsy needed for lentigo maligna melanoma?

BACKGROUND AND OBJECTIVES: Sentinel lymph node biopsy (SLNB) is an area of debate in the management of lentigo maligna melanoma (LMM). The utility of SLNB and its prognostic value in LMM have not yet been studied with large databases. METHODS: We performed a retrospective review of the National Cancer Database (2012-2020) and the Surveillance, Epidemiology, and End Results (2010-2019) database for patients with cutaneous nonmetastatic LMM with Breslow thickness >1.0 mm. Multivariable logistic regression identified factors associated with SLNB performance and sentinel lymph node (SLN) positivity. Univariable and multivariable analyses assessed overall survival (OS) and melanoma-specific survival (MSS) based on SLNB performance and SLN status. RESULTS: Compared to other melanoma subtypes, LMM had lower rates of SLNB (66.6% vs. 80.0%-84.0%) and SLN positivity (11.3% vs. 18.6%-34.2%). Compared to patients who did not undergo SLNB, SLN status was significantly associated with improved OS in patients with SLN positive (HR = 0.64 [0.55-0.76]) and SLN negative (HR = 0.68 [0.49-0.94]), and worse MSS only in patients with positive SLN (HR = 3.93, p < 0.05). CONCLUSION: The improved OS associated with SLNB likely implies surgical selection bias. Analysis of MSS confirms appropriate patient selection and suggests important prognostic value associated with SLN status. These results support continued SLNB for LMM patients according to standard guidelines.

Racial-Ethnic, Education, and Socioeconomic Differences in the Treatment of Head and Neck Melanoma in situ: A Surveillance Epidemiology and End Results Population-Based Analysis.

BACKGROUND: Incidence and treatment disparities for cutaneous melanomas have been documented among racial and sociodemographic minorities. However, the association between treatment types, race, and socioeconomic status remains unknown. OBJECTIVE: To characterize treatment differences for head and neck melanoma in situ (MIS) and lentigo maligna (LM) based on race and sociodemographic variables. MATERIALS AND METHODS: A population-based retrospective cohort study of the Surveillance Epidemiology and End Results database (1998-2016) was performed. Univariate and multivariate logistic regression modeling evaluated the association of race and US census-reported sociodemographic factors with Mohs micrographic surgery (MMS) utilization. RESULTS: A total of 76,328 adult patients with head and neck MIS/LM were included. MMS accounted for 11.8% of total cases, with increased utilization observed since 1998-2002. Compared with areas with greater percentages of individuals completing high school (first quartile), patients living in the second (Odds ratio [OR] 0.71; 95% confidence interval [CI] 0.64-0.80; p < .001), third (OR 0.74; 95% CI 0.63-0.86; p < .001), and fourth quartiles (OR 0.44; 95% CI 0.35-0.55; p < .001) were less likely to undergo MMS for their MIS/LM. CONCLUSION: Educational efforts and awareness can bridge the knowledge gaps of appropriate treatment in patients with head and neck MIS/LM.

The limited value of sentinel lymph node biopsy in lentigo maligna melanoma: A nomogram based on the results of 29 years of the nationwide dutch pathology registry (PALGA).

BACKGROUND: Lentigo maligna melanoma (LMM) predominantly presents in the head and neck of the elderly. The value of sentinel lymph node biopsy (SLNB) for LMM patients remains to be determined, as the reported average yield of positive lymph nodes is less than 10%. In this nationwide cohort study, we wanted to identify LMM patients with an increased risk of SLNB-positivity. METHODS: LMM with an SLNB indication according to the 8th AJCC melanoma guidelines were retrospectively identified from the nationwide network and registry of histo- and cytopathology in the Netherlands (PALGA). A penalized (LASSO) logistic regression analysis was performed to determine the optimal combination of clinicopathological factors to predict a positive SLNB. RESULTS: Between 1991 and 2020, 1989 LMM patients met our inclusion criteria. SLNB was performed in 16.7% (n = 333) and was positive in 7.5% (25/333). The false-negative rate was 21.9%. Clinically detectable regional lymph node (LN) metastases were found in 1.3% (n = 25). Clinicopathological characteristics best predictive for SLNB-positivity (Odds ratio; 95% CI) were age (0.95; 0.91-0.99), ulceration 1.59 (0.44-4.83), T4-stage (1.81; 0.43-6.2), male sex (1.97; 0.79-5.27), (lymph)angioinvasion (5.07; 0.94-23.31), and microsatellites (7.23; 1.56-32.7) (C-statistic 0.75). During follow-up, regional LN recurrences were detected in 4.2% (83/1989) of patients, of which the majority (74/83) had no evidence of regional LN metastases at baseline. CONCLUSION: Our findings confirm the limited SLNB-positivity in LMM patients. Based on the identified high-risk clinicopathological features, a nomogram was developed to predict the risk of a positive SLNB.

RECURRENT LENTIGO MALIGNA: CONSERVATIVE CONTINUOUS TREATMENT WITH IMIQUIMOD OR REPEATED SURGERY? A LONG-TERM FOLLOW-UP DERMOSCOPIC CASE STUDY.

A case of recurrent lentigo maligna in a 45-year-old woman is presented. The disease relapsed several times following the surgical excision of the lesion. An alternative treatment with imiquimod 5% cream was then used. After 4 years of follow-upfrom the last surgery, this treatment achieved total clearance of the lesion. The problems of lentigo maligna diagnosis and treatment are discussed.

Efficacy of imiquimod in the management of lentigo maligna.

BACKGROUND: Lentigo maligna (LM) is a melanocytic proliferation occurring on photo-exposed skin that may progress to LM melanoma. Surgery is recommended as first-line treatment. Excision margins of 5-10 mm remain, without international consensus. Several studies have shown that imiquimod, an immunomodulator, induces LM regression. This study investigated the effect of imiquimod versus placebo in neoadjuvant settings. PATIENTS AND METHODS: We performed a prospective, randomized, multicentre, phase III clinical study. Patients were randomly assigned in 1:1 ratio to receive imiquimod or placebo for 4 weeks, followed by LM excision 4 weeks after the last application of imiquimod or placebo. The primary endpoint was extra-lesional excision, with a 5 mm margin from the residual pigmentation after imiquimod or vehicle. Secondary endpoints included the gain on the surface removed between the two groups; number of revision surgeries to obtain extra-lesional excisions; relapse-free time; and number of complete remissions after treatment. RESULTS: A total of 283 patients participated in this study; 247 patients, 121 patients in the placebo group and 126 in the imiquimod group, accounted for the modified ITT population. The first extralesional extirpation was performed in 116 (92%) imiquimod patients and in 102 (84%) placebo patients; the difference was not significant (p = 0.0743). Regarding the surface of LM, imiquimod reduced the LM surface (4.6-3.1 cm2 ) significantly (p < 0.001) more compared to the placebo (3.9-4.1 cm2 ). CONCLUSION: Imiquimod reduces the lentigo maligna surface after 1 month of treatment, without a higher risk of intralesional excision and with a positive aesthetic outcome.

Surgical margin mapping for lentigo maligna and lentigo maligna melanoma: traditional technique (visual inspection with dermoscopy) versus combined paper tape and reflectance confocal microscopy technique.

BACKGROUND: The detection of subclinical margin in lentigo maligna/lentigo maligna melanoma (LM/LMM) can be challenging for the dermatologist. Reflectance confocal microscopy (RCM) enables to observe in vivo atypical melanocytes beyond the clinical margins. The aim of this study is to establish which of these methods (clinical examination and dermoscopy versus "Paper tape - RCM") is more precise to define the lesion margin and to reduce the number of re-intervention and overtreatments in cosmetically sensitive areas. METHODS: Fifty-seven cases of LM/LMM were analyzed during 2016-2022. Pre-surgical mapping procedures in 32 lesions were effectuated with dermatoscopy. Furthermore, pre-surgical mapping procedures in 25 lesions were effectuated with RCM and paper tape. RESULTS: RCM method's accuracy to detect subclinical margins was 92.0%. In 24 of 25 cases, the lesions were excised completely during the first intervention. In 20 of 32 cases analyzed with dermoscopy, a second surgical intervention was effectuated. CONCLUSION: The RCM paper method allows us to delineate subclinical margin more accurately and reduce overtreatment, especially in sensitive areas, such as the face and neck.

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.

Update on Lentigo Maligna: Diagnostic Signs and Treatment. / El lentigo maligno: actualización y claves en el diagnóstico y el tratamiento.

Lentigo maligna is an in situ cutaneous melanoma that arises in sun-damaged skin. Its most common presentation is a progressive, slow-growing, irregularly pigmented spot on the face of older patients. Although the exact percentage of Lentigo maligna that progresses to invasive tumors is unknown, it is thought to lie between 2% and 5%. Both the clinical and histologic diagnosis of Lentigo maligna can be challenging, especially in patients with early-stage or atypical disease. Treatment also holds challenges, because lesions are located in highly visible areas and are often large. Surgery can thus compromise cosmetic and sometimes functional outcomes. We review clinical and histopathological findings that can facilitate the diagnosis of Lentigo maligna. We also examine treatment options, with a focus on surgery.

Similar local recurrence and survival in patients with T1 radial growth phase melanoma on head and neck treated with 5 or 10 mm margins: A retrospective study.

BACKGROUND: Melanoma guidelines recommend surgical excision with 10 mm margins for T1 melanomas (invasive melanomas with Breslow thickness ≤1 mm), including those in radial growth phase, which are without metastatic potential; however, such margins may be problematic on head-and-neck. OBJECTIVE: We compared outcomes of wide (10 mm margins) versus narrow (5 mm margins) excisions in patients with radial growth phase T1 melanoma on head-and-neck including face. METHODS: We retrospectively examined 610 consecutive patients excised with wide versus narrow margins, from 2001 to 2018, at six European centres. In all cases, radial growth phase, and clear margins with 5 or 10 mm of clearance, were ascertained histologically. Multivariable models investigated associations of margins and other factors with overall survival and local recurrence. RESULTS: Three hundred and sixteen (51.8%) patients received wide excision, 219 (69.3%) with primary wound closure, 97 (30.7%) with reconstruction; 294 (48.2%) patients received narrow excision, 264 (89.8%) with primary wound closure, 30 (10.2%) with reconstruction (p < 0.001). Median follow-ups were 88 months (wide) and 187 months (narrow) (inter-quartile ranges 43-133 and 79-206, respectively). Ten-year overall survival (95% confidence interval) was 96.7% (94.2%-99.3%) in wide and 98.2% (96.4%-100%) in narrow patients. Ten-year local recurrence incidence was 6.4% (4.1%-10.1%) in wide and 7.8% (5.3%-11.6%) in narrow groups. Lentigo maligna melanoma subtype appeared associated with increased risk of local recurrence in narrow versus wide patients (15.0% vs. 7.5%; p = 0.190). CONCLUSIONS: Narrower excision margins for T1 radial growth phase melanoma are not associated with worse overall survival (hazard ratio 0.97, p = 0.996) or increased local recurrence (subdistribution hazard ratio: 0.87; p = 0.751) compared to wider margins, and may be safely applied to such lesions, although caution may be required in the presence of lentigo maligna melanoma.

Long-term outcomes of margin-controlled excision for eyelid melanoma.

OBJECTIVES: To provide evidence for long-term outcomes for margin-controlled excision of eyelid melanoma. METHODS: Retrospective single-centre observational case series of patients treated for eyelid melanoma between 2007 and 2016, with a minimum of 5-year follow-up. Tumour excision involved rush-paraffin en face horizontal sections and delayed repair (Slow Mohs; SM). RESULTS: Twenty-two cases were seen with a survival of 91% (two deaths from nodular and lentigo maligna melanoma) and seven with melanoma in situ (MIS). Invasive melanoma includes eight lentigo maligna melanoma, four nodular, two amelanotic and one desmoplastic. Mean Breslow thickness was 6 mm for invasive (range 0.5-26). Mean excision margin for MIS was 3 mm (range 2-5 mm) and for invasive was 5 mm (range 2-10). Further excisions were performed in nine (41%); two went on to recur. Local recurrence was 36%; six invasive (27%) at a mean of 24 months (range 1.5-5 years) and two for MIS at a mean of 15 months (range 1-1.5 years). Imaging occurred for suspected advanced disease. Sentinel node biopsy was not performed. Advanced melanoma therapy was performed in two cases. No vitamin D testing occurred. CONCLUSIONS: Survival rates are in line with 90% overall survival in the UK. Prescriptive excision margins are not applicable in the periocular region and margin-controlled excision with a delayed repair is recommended, but patients need to know further excision may be needed to obtain clearance. Evidence recommending vitamin D therapy needs to be put into clinical practice. In addition, upstaging of MIS occurred advocating excision rather than observation of MIS. More studies are needed to determine the best management of eyelid melanoma.

Lentigo maligna melanoma mapping using reflectance confocal microscopy correlates with staged excision: A prospective study.

BACKGROUND: Lentigo maligna/lentigo maligna melanoma (LM/LMM) can present with subclinical extension that may be difficult to define preoperatively and lead to incomplete excision and potential recurrence. Preliminarily studies have used reflectance confocal microscopy (RCM) to assess LM/LMM margins. OBJECTIVE: To evaluate the correlation of LM/LMM subclinical extension defined by RCM compared with the gold standard histopathology. METHODS: Prospective study of LM/LMM patients referred for dermatologic surgery. RCM was performed at the clinically defined initial surgical margin followed by margin-controlled staged excision with paraffin-embedded tissue, and histopathology was correlated with RCM results. RESULTS: Seventy-two patients were included. Mean age was 66.8 years (standard deviation, 11.1; range, 38-89); 69.4% were men. Seventy of 72 lesions (97.2%) were located on the head and neck with mean largest clinical diameter of 1.3 cm (range, 0.3-5). Diagnostic accuracy for detection of residual melanoma in the tumor debulk (after biopsy) had a sensitivity of 96.7% and a specificity of 66.7% when compared with histopathology. RCM margin assessment revealed an overall agreement with final histopathology of 85.9% (κ = 0.71; P < .001). LIMITATIONS: No RCM imaging beyond initial planned margins was performed. CONCLUSION: RCM showed moderate to excellent overall agreement between RCM imaging of LM/LMM and histopathology of staged excision margins.