Prognostic markers in lentigo maligna patients treated with imiquimod cream: A long-term follow-up study

Melanocyte Density in the Diagnosis of Melanoma In Situ in Sun-Damaged Skin

ABSTRACT

Histologic differentiation between melanoma in situ in chronically sun-damaged skin (CSDS) [lentigo maligna (LM)] and CSDS without malignancy is difficult because signs of melanocyte activation and proliferation are found in both. A potentially reliable and quantifiable criterion is melanocyte density (MD). Here, we evaluated whether and to what extent MD allows the distinction between LM and CSDS, which is particularly relevant for the evaluation of borderline cases and surgical margins.Articles assessing MD in LM and/or CSDS were evaluated in a systematic review. The results were categorized and compared according to staining. Cutoff values were included whenever stated.Twenty articles matched the selection criteria. Six hundred forty-four samples of CSDS and 227 samples of LM were considered. In each individual study, mean MD scores were higher for LM than for CSDS. However, looking at the overall study situation, it becomes clear that the data are very heterogeneous and show overlaps. Therefore, no reliable orientation value can be derived. Only 1 article defined a cutoff value.The data of MD in LM in contrast to CSDS were sparse, and a defined cutoff value was only mentioned in 1 article for microphthalmia-associated transcription factor, which cannot yet be generalized. Especially regarding the importance for the definition of surgical resection margins, this unsatisfactory data set highlights the need for further studies. More precise diagnostic criteria could spare some patients extensive and possibly disfiguring surgery.

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.

Topical Treatment of Melanoma In Situ, Lentigo Maligna, and Lentigo Maligna Melanoma with Imiquimod Cream: A Systematic Review of the Literature

INTRODUCTION

The classical management of melanoma is surgery, but this can be challenging because of several factors, such as age, body area, lesion size, among others. Topical imiquimod may be a therapeutic option for the treatment of melanoma in situ and lentigo maligna melanoma due to its efficacy, tolerability, and non-invasiveness. The purpose of this systematic review is to assemble current evidence on the treatment of non-metastatic melanoma with topical imiquimod.

METHODS

The PubMed/MEDLINE and Cochrane Library databases were searched as the primary sources using the main search terms "imiquimod" combined with "lentigo maligna" and "melanoma" with the command "AND." Articles were identified, screened, and extracted for relevant data, following the PRISMA guidelines.

RESULTS

A total of 87 studies covering 1803 lesions treated with imiquimod cream were identified and included in this sytematic review. Forty-nine studies were case reports, 16 were retrospective analyses, 3 were open label trials, six were case series; one study was a controlled randomized trial, one was a randomized trial, and one was a single-arm phase III trial. Because of the high number of low-evidence studies, the overall risk of bias resulted high. In 55 studies, imiquimod 5% was used in monotherapy as the primary treatment; only in one study was imiquimod 3.75% introduced. In most cases, the topical treatment was applied once daily, with the exception of nine cases where an increased daily dosage was prescribed. The total duration of the treatment regimen was extremely variable and depended on body area and tolerability, with differences among patients of the same study. In six studies, imiquimod was used as neoadjuvant therapy before the surgical excision, and in 11 studies it was used after surgery as complementary or adjuvant therapy. In total, 1133 of the 1803 (62.8%) lesions were reported to be cleared after the treatment, taking into account that not all of the patients completed the treatment. Of these 1133 lesions, histological clearance was achieved in 645 (56.9%) lesions and clinical clearance only was achieved in 490 (43.2%) lesions; relapse occurred in 107 lesions.

CONCLUSIONS

The heterogeneity of the studies included in this systematic review precludes the drawing of any relevant conclusions regarding the application of imiquimod. Its efficacy in melanoma in situ and lentigo maligna melanoma has been demonstrated, but further evidence from controlled studies concerning the modalities is missing.

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.

Long-Term Follow-Up of Lentigo Maligna Patients Treated with Imiquimod 5% Cream

BACKGROUND

The study investigated the long-term efficacy of imiquimod 5% cream for LM, with a focus on disease recurrence and the possible prognostic factors of disease-free survival (DFS) in a cohort, with long-term follow-up.

METHODS

Consecutive patients with histologically confirmed LM were included. Imiquimod 5% cream was applied until weeping erosion appeared on the LM-affected skin. The evaluation was performed through clinical examination and dermoscopy.

RESULTS

We analyzed 111 patients with LM (median age: 72 years, 61.3% women) with tumor clearance after imiquimod therapy, with a median follow-up of 8 years. The overall patient survival rates were 85.5% (95% confidence interval (CI): 78.5-92.6) and 70.4% (95% CI: 60.3-80.5) at 5 and 10 years, respectively. Among the 23 patients (20.1%) with relapse at follow-up, 17 (73.9%) were treated with surgery, five (21.7%) continued imiquimod therapy, and one (4.3%) underwent both surgery and radiotherapy. After adjustment for age and LM area in multivariable models, localization of LM in the nasal region was identified as a prognostic factor for DFS (HR = 2.66; 95% CI: 1.06-6.64).

CONCLUSION

If surgical excision is not possible due to the patients' age/comorbidities or critical cosmetic localization, imiquimod could provide optimal outcomes with an optimal risk of relapse for the management of LM.

In vivo tumor immune microenvironment phenotypes correlate with inflammation and vasculature to predict immunotherapy response

Response to immunotherapies can be variable and unpredictable. Pathology-based phenotyping of tumors into ‘hot’ and ‘cold’ is static, relying solely on T-cell infiltration in single-time single-site biopsies, resulting in suboptimal treatment response prediction. Dynamic vascular events (tumor angiogenesis, leukocyte trafficking) within tumor immune microenvironment (TiME) also influence anti-tumor immunity and treatment response. Here, we report dynamic cellular-level TiME phenotyping in vivo that combines inflammation profiles with vascular features through non-invasive reflectance confocal microscopic imaging. In skin cancer patients, we demonstrate three main TiME phenotypes that correlate with gene and protein expression, and response to toll-like receptor agonist immune-therapy. Notably, phenotypes with high inflammation associate with immunostimulatory signatures and those with high vasculature with angiogenic and endothelial anergy signatures. Moreover, phenotypes with high inflammation and low vasculature demonstrate the best treatment response. This non-invasive in vivo phenotyping approach integrating dynamic vasculature with inflammation serves as a reliable predictor of response to topical immune-therapy in patients.

Standard assessment of immune infiltration of biopsies is not sufficient to accurately predict response to immunotherapy. Here, the authors show that reflectance confocal microscopy can be used to quantify dynamic vasculature and inflammatory features to better predict treatment response in skin cancers.

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.

Change in lentigo maligna score assessed by in vivo reflectance confocal microscopy after 1 month of imiquimod treatment for lentigo maligna management

BACKGROUND

Treatment of lentigo maligna (LM) is challenging because of the potential functional and esthetic surgical sequelae. Imiquimod has been proposed as a treatment for LM. Reflectance confocal microscopy (RCM) is a noninvasive method for the diagnosis of LM and margin assessment.

OBJECTIVES

To compare the overall LM score (LMS) assessed by RCM before and 1 month after the start of imiquimod treatment compared to placebo and to define the immunohistochemical (IHC) profile of responders to imiquimod.

METHODS

A controlled randomized study was conducted. Forty patients underwent RCM examination with calculation of the LMS at baseline and after 1 month of treatment. An IHC analysis of excised tissues was performed.

RESULTS

The 1-month LMS was significantly lower in patients treated with imiquimod compared to those treated with placebo (P < .001). The criteria in the imiquimod-treated patients that demonstrated significant decrease were nonedged papillae; large, round pagetoid cells; atypical cells at the dermoepidermal junction; and follicular location of atypical cells. IHC analysis showed a higher level of interferon gamma in the resected specimens of patients responding to imiquimod (P = .04).

LIMITATIONS

Sample size was small.

CONCLUSION

Assessing the LMS by RCM was useful to monitor LM response to imiquimod accurately.

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.

Update on Current Treatment Recommendations for Primary Cutaneous Melanoma

Primary cutaneous melanoma describes any primary melanoma lesion of the skin that does not have evidence of metastatic disease. This article reviews the current workup, treatment, and follow-up recommendations for primary cutaneous melanoma (stages 0, I, and II). Specific attention is focused on recent updates with regard to staging, sentinel lymph node biopsy, and surgical modalities.

The use of 2940-nm ER:YAG laser for the treatment of lentigo maligna

OBJECTIVES

Lentigo maligna is a common in situ malignancy in elderly patients, with a low risk of progression to an invasive tumor. Surgical treatment may be complicated or refused. Non-surgical treatment options (such as lasers) may therefore be needed.

PATIENTS AND METHODS

We report on 17 patients treated with a 2940-nm Er:YAG (erbium-doped yttrium aluminum) laser for histopathologically confirmed lentigo maligna. The lesions were ablated with a 5 mm margin of adjacent skin under local anesthesia with a 3.5 mm overlapping spot, energy density of 6.5 J/cm² and a repetition rate of 5 Hz. If clinically visible pigmentation was seen in the ablated area during the following three months, the lesion was re-treated. All patients were followed up for residual or recurrent tumors.

RESULTS

We achieved clinical clearance in all 17 patients. There were three recurrences during the follow-up period (9, 30 and 36 months after laser therapy). All patients were satisfied with the treatment course and cosmetic outcome. The mean follow-up duration was 28 months.

CONCLUSIONS

Laser ablation is an interesting alternative method for treatment of lentigo maligna. It can be used for selected cases where surgery is contraindicated, complicated or declined by the patient.

Confocal Microscopy and Lentigo Maligna: An in vivo Pilot Study for the Assessment of Response to Imiquimod Therapy

Background: Reflectance confocal microscopy (RCM) is a noninvasive technique that provides real-time in vivo images of the epidermal layer. Imiquimod has been recommended as an alternative treatment in lentigo maligna (LM) when surgical excision is not the treatment of choice. In the present study we compare the results of in vivo RCM to the histopathological examination before and after treatment of LM with topical imiquimod. Methods: Thirty-four patients with confirmed LM were included. Imiquimod 5% was applied until a weeping erosion appeared in the LM-affected skin. Evaluation was performed by clinical examination, dermatoscopy, histopathology and RCM. Results: During the follow-up, 27 of 34 patients (79.42%) demonstrated a total tumor clearance by imiquimod treatment. In the treated area, a significant decrease of atypical cells was detected using RCM (p < 0.0001). Furthermore, a significant positive correlation in the detected atypical cells was shown using confocal microscopy and histology (p = 0.0001, r = 0.7335, respectively). Conclusion: In patients not suitable for surgical intervention imiquimod treatment is an appropriate treatment alternative. Thereby, in vivo RCM was demonstrated to be an excellent examining device, which not only allows diagnosis of LM, but also therapy and follow-up examinations. An important benefit of RCM, in contrast to conventional histopathology, is the simple handling with in vivo examination of epidermal skin without any pain for the patient.

Follicular involvement is frequent in lentigo maligna: Implications for treatment

BACKGROUND

Follicular involvement of lentigo maligna (LM) is considered a histopathologic hallmark, but its prevalence and characteristics have not been well defined. The depth of intrafollicular extension by neoplastic melanocytes may have clinical importance in the treatment of LM.

OBJECTIVE

To describe the prevalence and features of follicular involvement in LM, including depth of follicular growth by melanocytes.

METHODS

A single-center retrospective study of 100 consecutive cases of surgically excised LM that was treated from 2013 to 2015. The slide review for cases with residual LM on the debulk specimen was performed by a dermatologic surgeon and dermatopathologist to characterize follicular involvement.

RESULTS

Of 100 specimens, 72 met the inclusion criteria for histopathologic evaluation. Follicular involvement was seen in 95.8% of specimens (95% confidence interval, 88.3%-99.1%), with a mean of 68% of follicles involved in a single specimen. The mean depth of intrafollicular growth by lesional melanocytes was 0.45 mm (standard deviation, 0.23; range, 0.1-1.1 mm). Tumor cells were confined to the infundibular portion of the hair follicle in 60.9% of specimens.

CONCLUSION

Superficial follicular involvement is a ubiquitous finding in LM. When treatment options for LM with a depth-dependent modality aiming for tumor clearance are being considered, mean and maximum depths of involvement should be taken into consideration.

Lentigo maligna: diagnosis and treatment

Lentigo maligna (LM) is an in situ subtype of melanoma, clinically presenting as a pigmented, asymmetric macule that originates mostly on the head and neck and spreads slowly. The diagnosis may be challenging both for clinicians and pathologists. Dermatoscopy and reflectance confocal microscopy represent a useful tool in the differentiation of LM from other pigmented lesions, such as pigmented actinic keratosis, solar lentigines, seborrheic keratosis and lichen planus-like keratosis. Moreover, those non-invasive diagnostic technique may be crucial in the selection of optimal biopsy sites in equivocal lesions, in pre-surgical mapping and in evaluating and monitoring response to non-surgical treatments. Histologic examination remains the gold standard for the diagnosis of LM, showing a lentiginous proliferation of basal atypical melanocytes on a severe sun-damaged skin. The management of LM is constantly evolving. Treatments include surgery (the first choice, when available), radiotherapy and imiquimod cream (in patients not candidates to surgery). Many other possible treatments for LM have been tested, but they are not yet supported by strong evidences. We collected current guidelines and PubMed available reviews, studies and case-reports in order to make an overview on diagnosis and treatment of LM.

Amelanotic Lentigo Maligna Melanoma: Mohs Surgery as the Definitive Treatment of an Invisible Tumour

Amelanotic lentigo maligna melanoma represents <2% of melanomas. Diagnosis is delayed owing to the lack of lesion pigmentation and advanced disease at presentation. Excision with appropriate margins is the treatment standard, but the starting point for such margins is often unclear. We describe 2 patients with amelanotic melanoma treated by Mohs micrographic surgery (MMS) that would not have been cleared by wide local excision alone and provide an extensive review of the literature. Both patients presented with histologic diagnoses of malignant melanoma, one with a barely perceptible biopsy site scar on the left infraorbital cheek/lower eyelid (Breslow 1.8 mm) and the second with an amelanotic tumour on the right helix (Breslow 10 mm). Due to location, aggressive histology, amelanotic appearance, and no apparent surrounding skin surface changes, MMS was elected to maximise margin control. For patient 1, invasive and in situ tumour was found at the American Joint Committee on Cancer–recommended margin of 1.5 cm, and the final defect measured 8.5 × 4.8 cm. Patient 2 had a significant invasive and amelanotic lentigo maligna component, resulting in a 9.0 × 6.5-cm defect. MMS allows for immediate histologic feedback on tumour margins of a clinically invisible tumour and thus offers the most definitive treatment.

Lentigo Maligna, Macules of the Face, and Lesions on Sun-Damaged Skin: Confocal Makes the Difference

Distinguishing lentigo maligna (LM) and lentigo maligna melanoma (LMM) from background pigmented non-melanoma lesions is challenging. The field of solar damage can obscure clinical assessment, and diagnostic ambiguities are created due to the overlap of the clinical features of LM with other benign lesions. Moreover, margin assessment on histology is limited by the resemblance between melanocytic hyperplasia of actinically damaged skin and scattered atypical melanocytes of LM/LMM. Dermoscopy has made a significant contribution but is often not sufficient for diagnosis and margin assessment. Confocal microscopy has become an important complementary tool in enhancing the management of these complex lesions.

Lentigo maligna - anatomic location as a potential risk factor for recurrences after non-surgical treatment

Background

A higher incidence of lentigo maligna (LM) recurrences on the nose was previously observed in our cohort after non‐surgical treatment.

Objectives

To determine histological parameters that might be related to the previously observed higher incidence of LM recurrences on the nose after non‐surgical treatment.

Methods

We randomly selected 22 surgical specimens of LM on the nose and 22 on the cheek. Histopathological analysis was performed on haematoxylin and eosin stained and microphthalmia transcription factor immunohistochemically stained slides. The number of pilosebaceous units (PSU) per mm, maximum depth of atypical melanocytes along the skin appendages and maximum depth of the PSU itself were determined.

Results

The nose had a significantly higher density of PSU than the cheek. The atypical melanocytes extended deeper along the PSU on the nose with a mean (SD) depth of 1.29 mm (0.48) vs. a mean depth of 0.72 mm (0.30) on the cheek (P < 0.001). The maximum depth of the PSU on the nose was greater than on the cheek, mean (SD) depth of 2.28 mm (0.41) vs. 1.65 mm (0.82) (P = 0.003).

Conclusions

The higher recurrence risk of LM on the nose after non‐surgical treatment that we previously observed in our cohort is most likely based on a higher density of atypical melanocytes and also their deeper extension into the follicles. These results shed more light on our previous findings and learn that anatomical location is relevant for the risk of recurrence of LM after non‐surgical treatment.