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.

The combination of dermoscopy and reflectance confocal microscopy increases the diagnostic confidence of amelanotic/hypomelanotic lentigo maligna

The dermoscopic diagnosis of amelanotic/hypomelanotic lentigo maligna/lentigo maligna melanoma (AHLM/LMM) may be very difficult in its early stages because of lack of pigment. Reflectance confocal microscopy (RCM) is an imaging technique that is especially helpful for the diagnosis of lentigo maligna. To determine the diagnostic performances of dermoscopy and RCM in the diagnosis of AHLM/LMMs we evaluated dermoscopic and RCM images of consecutive cases of histopathologically confirmed AHLM/LMMs, amelanotic/hypomelanotic basal cell carcinoma and squamous cell carcinoma (AHBCCs/AHSCCs), amelanotic/hypomelanotic benign lesions (AHBLs), and actinic keratoses (AKs) from five participating centers. Sensitivity, specificity, accuracy, predictive values, and level of diagnosis confidence were calculated for both diagnostic procedures. Both dermoscopy and RCM showed diagnostic performance >97% in the diagnosis of AHLM/LMMs versus AHBCC/AHSCCs and their combination slightly improved diagnostic performance, with accuracy increasing from 98.0% to 99.1%. Similarly, RCM in combination with dermoscopy showed a tiny increase in the diagnostic performance in the diagnosis of AHLM/LMMs versus AHBLs (accuracy increased from 87.2% to 88.8%) and versus AKs (accuracy increased from 91.4% to 93.4%). Although the increase in diagnostic performance due to RCM was modest, the combination of dermoscopy and RCM greatly increased the level of confidence; high confidence in the diagnosis of AHLM/LMMs versus AHBLs increased from 36.2% with dermoscopy alone to 76.6% with dermoscopy plus RMC. Based on our results, dermoscopy and RCM should be complementary to improve not only diagnostic accuracy but also the level of diagnostic certainty in the diagnosis of AHLM/LMMs.

Lentigo maligna: a review

Lentigo maligna (LM) is a melanoma in situ with distinct clinical features and histology. It commonly affects men after the sixth decade of life. Incidence rates of LM have increased based on early 21st century data from different countries; however, data are suboptimal. Data from England show a plateauing crude incidence between 2013 and 2019. By comparison, invasive melanoma and other types of melanoma in situ commonly appears in younger age groups (median age 58 and 67 years old, respectively) and incidence is rising. The most important risk factors for LM include fair skin and cumulative ultraviolet solar radiation exposure. Although LM is limited to the epidermis and connected skin adnexa, it may progress to invasive LM melanoma. The reported rate of malignant progression varies, reflecting a challenge for LM epidemiology research as often lesions are removed on diagnosis. LM poses a challenge in diagnosis and management. Although it can be diagnosed clinically or dermoscopically, histopathological assessment of biopsied skin tissue remains the gold standard. Reflectance confocal microscopy allows for better appreciation of the complexity of LM at a cellular level, often progressing beyond clinical margins. Management of LM may involve Mohs micrographic surgery or excision, although recurrence may occur even with 5 mm clinical margins. Imiquimod cream may be effective, but incomplete treatment and recurrence has been reported. Conservative management with observation or radiotherapy may be used in selected patients' cases. Five-year net survival rates are excellent. This paper reviews the natural history, epidemiology, aetiology, pathogenesis, diagnosis and management of LM.

Lentigo maligna and lentigo maligna melanoma in vivo differentiation with dermoscopy and reflectance confocal microscopy: A retrospective, multicentre study

INTRODUCTION

Dermoscopic predictors of lentigo maligna (LM) and lentigo maligna melanoma (LMM) have been recently reported, but these have not been reported in reflectance confocal microscopy (RCM).

OBJECTIVES

(i) To validate dermoscopic predictors for LM/LMM, (ii) to identify RCM patterns in LM and LMM, and (iii) correlations between dermoscopic and RCM features in LM and LMM.

MATERIALS AND METHODS

A retrospective, multicentre study of consecutive lesions with histologically proven LM or LMM subtypes of the head and face, with complete sets of dermoscopic and RCM images.

RESULTS

A total of 180 lesions were included (n = 40 LMM). Previously reported differential dermoscopic features for LM subtypes were confirmed. Other features significantly associated with LMM diagnosis included irregular hyperpigmented areas, shiny white streaks, atypical vessels and light brown colour at dermoscopy and medusa head-like structures, dermal nests and nucleated cells within the papillae at RCM (p < 0.05). Correlations among LM lesions between dermoscopic and RCM features included brown to-grey dots and atypical cells (epidermis), grey colour and inflammation and obliterated follicles and medusa head-like structures. Among LMM lesions, significant correlations included obliterated follicles with folliculotropism, both irregular hyperpigmented areas and irregular blotches with widespread atypical cell distribution (epidermis), dermal nests and nucleated cells within the papillae (dermis). Irregular blotches were also associated with medusa head-like structures (dermal epidermal junction [DEJ]).

CONCLUSIONS

Dermoscopic and RCM features can assist in the in vivo identification of LM and LMM and many are correlated. RCM three-dimensional analysis of skin layers allows the identification of invasive components in the DEJ and dermis.

A risk-scoring model for the differential diagnosis of lentigo maligna and other atypical pigmented facial lesions of the face: The facial iDScore

BACKGROUND

Due to progressive ageing of the population, the incidence of facial lentigo maligna (LM) of the face is increasing. Many benign simulators of LM and LMM, known as atypical pigmented facial lesions (aPFLs-pigmented actinic keratosis, solar lentigo, seborrheic keratosis, seborrheic-lichenoid keratosis, atypical nevus) may be found on photodamaged skin. This generates many diagnostic issues and increases the number of biopsies, with a subsequent impact on aesthetic outcome and health insurance costs.

OBJECTIVES

Our aim was to develop a risk-scoring classifier-based algorithm to estimate the probability of an aPFL being malignant. A second aim was to compare its diagnostic accuracy with that of dermoscopists so as to define the advantages of using the model in patient management.

MATERIALS AND METHODS

A total of 154 dermatologists analysed 1111 aPFLs and their management in a teledermatology setting: They performed pattern analysis, gave an intuitive clinical diagnosis and proposed lesion management options (follow-up/reflectance confocal microscopy/biopsy). Each case was composed of a dermoscopic and/or clinical picture plus metadata (histology, age, sex, location, diameter). The risk-scoring classifier was developed and tested on this dataset and then validated on 86 additional aPFLs.

RESULTS

The facial Integrated Dermoscopic Score (iDScore) model consisted of seven dermoscopic variables and three objective parameters (diameter ≥ 8 mm, age ≥ 70 years, male sex); the score ranged from 0 to 16. In the testing set, the facial iDScore-aided diagnosis was more accurate (AUC = 0.79 [IC 95% 0.757-0.843]) than the intuitive diagnosis proposed by dermatologists (average of 43.5%). In the management study, the score model reduced the number of benign lesions sent for biopsies by 41.5% and increased the number of LM/LMM cases sent for reflectance confocal microscopy or biopsy instead of follow-up by 66%.

CONCLUSIONS

The facial iDScore can be proposed as a feasible tool for managing patients with aPFLs.

In vivo reflectance confocal microscopy can detect the invasive component of lentigo maligna melanoma: Prospective analysis and case-control study

BACKGROUND

Lentigo maligna (LM), a form of melanoma in situ, has no risk of causing metastasis unless dermal invasive melanoma (LMM) supervenes. Furthermore, the detection of invasion impacts prognosis and management.

OBJECTIVE

To assess the accuracy of RCM for the detection of invasion component on LM/LMM lesions.

METHODS

In the initial case-control study, the performance of one expert in detecting LMM at the time of initial RCM assessment of LM/LMM lesions was recorded prospectively (n = 229). The cases were assessed on RCM-histopathology correlation sessions and a panel with nine RCM features was proposed to identify LMM, which was subsequently tested in a subset of initial cohort (n = 93) in the matched case-control study by two blinded observers. Univariable and multivariable logistic regression models were performed to evaluate RCM features predictive of LMM. Reproducibility of assessment of the nine RCM features was also evaluated.

RESULTS

A total of 229 LM/LMM cases evaluated by histopathology were assessed blindly and prospectively by an expert confocalist. On histopathology, 210 were LM and 19 were LMM cases. Correct identification of an invasive component was achieved for 17 of 19 LMM cases (89%) and the absence of a dermal component was correctly diagnosed in 190 of 210 LM cases (90%). In the matched case-control (LMM n = 35, LM n = 58), epidermal and junctional disarray, large size of melanocytes and nests of melanocytes were independent predictors of LMM on multivariate analysis. The interobserver analysis demonstrated that these three features had a fair reproducibility between the two investigators (K = 0.4). The multivariable model including those three features showed a high predictive performance AUC = 74% (CI 95% 64-85%), with sensitivity of 63% (95% CI 52-78%) and specificity of 79% (CI 95% 74-88%), and likelihood ratio of 18 (p-value 0.0026).

CONCLUSION

Three RCM features were predictive for identifying invasive melanoma in the background of LM.

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.

PRAME immunohistochemistry as an adjunct for diagnosis and histological margin assessment in lentigo maligna

AIMS

Lentigo maligna (LM), the most common type of melanoma in situ, is a diagnostically challenging lesion for pathologists due to abundant background melanocytic hyperplasia in sun-damaged skin. Currently, no laboratory methods reliably distinguish benign from malignant melanocytes. However, preferentially expressed antigen in melanoma (PRAME) has shown promise in this regard, and could potentially be applied to diagnosis and margin assessment in difficult cases of LM.

METHODS AND RESULTS

Ninety-six cases with a diagnosis of LM (n = 77) or no residual LM (n = 19) following initial biopsy were identified and stained with an antibody directed towards PRAME. Immunohistochemistry (IHC) was scored as positive or negative, and measurement of histological margins by PRAME was performed and compared to the measurement of histological margins using conventional methods [haematoxylin and eosin (H&E) and/or sex-determining region Y-box 10 (SOX10) and/or Melan-A]. Of cases with LM, 93.5% (72 of 77) were PRAME+ and 94.7% (18 of 19) of cases with no residual LM were PRAME- . Of the 35 cases with no margin involvement by PRAME or conventional assessment, 14 cases (40.0%) had no difference in measurement, 17 (48.6%) had a difference of 1 mm or less and four (11.4%) differed by between 1 and 3.5 mm. There was a high correlation between margin assessment methods (r = 0.97, P < 0.0001).

CONCLUSIONS

PRAME IHC is a sensitive (93.5%) and specific (94.7%) method for diagnosing LM on biopsy and excision, and measurement of histological margins by PRAME shows a high correlation with conventional methods for margin assessment. Furthermore, the nuclear expression of PRAME makes it a good target for use in dual-colour IHC stains.

Clinical size is a poor predictor of invasion in melanoma of the lentigo maligna type

BACKGROUND

There are no well-defined clinical factors to predict the risk of occult invasion in melanoma of the lentigo maligna type (LM) before complete histopathologic analysis.

OBJECTIVE

To evaluate whether clinical size was a predictor of invasion in LM and subclinical extension.

METHODS

Consecutive cases of LM were recorded in a prospectively maintained database from 2006 to 2019. Patient and tumor data were recorded during initial evaluation. The LM clinical area was calculated in square millimeters (length × width). All patients were treated with staged excision.

RESULTS

We included 600 patients. The mean age was 65.9 years (standard deviation, 12.3; range, 27-95 years); 62.8% (n = 377) were men. The mean LM clinical area was 128.32 mm² for in situ lesions versus 200.14 mm for invasive lesions (P = .1). Based on quantile regression, the median margin required for complete removal increased with LM clinical area.

LIMITATIONS

The study was performed in a tertiary cancer center with possible referral bias and more complex cases.

CONCLUSIONS

LM can present with variable clinical size, which may correlate with subclinical extension; however, the presence of invasion is not well estimated by LM clinical area.

Differential Expression of Cancer Testis Antigens on Lentigo Maligna and Lentigo Maligna Melanoma

The cancer/testis antigens (CTA) are a group of antigens expressed on germ cells of healthy testis and malignant tumors. We studied whether CTA are present on lentigo maligna (LM) and LM melanoma (LMM) samples. Immunohistochemical expression of a panel of CTA (MAGE-A1, A2- A3, NY-ESO-1, PRAME, SSX-2, and a MAGE-A antibody reactive with -A1, -A2, -A3, -A4, -A6, -A10, and -A12) was investigated in formalin-fixed paraffin-embedded samples from LMM (n = 20), LM (n = 8), chronically sun-exposed skin (n = 7), and healthy skin (n = 7). In 4 LMM lesions, the MAGE-A marker was positive. Another 3 LMM lesions were positive for MAGE-A1, MAGE-A2, and MAGE-A3. PRAME was positive in 18/20 LMM and 6/8 LM. We did not find expression of MAGE, NY-ESO-1, or SSX-2 in LM, thereby excluding these CTA as diagnostic markers to discern malignant melanocytes in LM from normal melanocytes. LMM did express MAGE, NY-ESO-1, and SSX-2. If a biopsy from a lesion suspect for LM shows positivity for MAGE, NY-ESO-1, and SSX-2, the lesion may actually be LMM. In contrast, PRAME expression was found in LM at low levels and in LMM at much higher levels, and absent in normal melanocytes. PRAME can potentially be used to discern normal melanocytes from malignant melanocytes.

[Diagnostics and treatment of lentigo maligna melanoma in Denmark]

The incidence of maligna melanoma has doubled in Denmark over the latest 30 years. Lentigo maligna melanomas (LMM) account for 10-26% of the melanomas in head and neck. LMM most often strike people over the age of 70 years and frequently occur in sun-exposed skin areas. LMM can be difficult to diagnose, since its clinical features are similar to benign skin lesions, solar lentigo and seborrhoeic keratosis. This review presents various methods for diagnosing and treating LMM. The specific method is chosen in dialogue with the patients, and overall health is an important factor when choosing an appropriate treatment.

Dermoscopic Differentiation of Facial Lentigo Maligna from Pigmented Actinic Keratosis and Solar Lentigines

The differential diagnosis of lentigo maligna (LM) from pigmented actinic keratosis (PAK) and solar lentigines (SL) remains a challenge for clinicians, especially in the early stages of LM when there are no distinctive dermoscopic features. Objective of this study was to evaluate the frequencies of selective dermoscopic criteria in LM, PAK, and SL and to find the specific combination of distinguishing dermoscopic criteria for LM. Dermoscopists blinded to histopathological diagnosis evaluated 42 LM, 107 PAK, and 16 SL for the presence of predefined dermoscopic criteria. The differences in the presence of dermoscopic criteria between LM and others were evaluated with the chi-squared test or Fisher's exact test as appropriate. Multivariate logistic regression analysis with the forward conditional stepwise method were performed and odds ratios and corresponding 95% confidence intervals for LM, PAK, and SL were calculated. LM, PAK, and SL showed many common dermoscopic findings. In multivariate logistic regression analysis, darkening at dermoscopic examination (sevenfold), gray circles (sevenfold), target-like pattern (sixfold), gray rhomboids (sixfold), and slate-gray dots/globules (threefold) represented the strongest predictors of LM, while hyperkeratosis (thirteenfold), white circles (twelvefold), and red rhomboids (sixfold) represented the strongest predictors of PAK. The dermoscopic diagnosis of a given lesion should be based on the presence of the combination of specific dermoscopic criteria rather than a single benign or malignant criterion. Our results suggest that the presence of darkening at dermoscopic examination, gray circles, target-like pattern, gray rhomboids, and slate-gray dots/globules should be considered supportive findings for the diagnosis of early LM.

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.

Dermoscopy findings of a one mm lentigo maligna

A 66-year-old man presented with a grayish 1mm macule on the left cheek. Dermatoscopic examination revealed annular-granular structures partially surrounding a single follicular ostium. Histopathologic examination demonstrated atypical, confluent single melanocytes at the basal layer with nesting, crowding, and upward migration descending along the hair follicle, consistent with the diagnosis of lentigo maligna (LM). This case presents evidence in support of the Schiffner progression model for LMs, starting with asymmetric pigmented follicular openings composed of annular-granular structures, which later coalesce into gray to dark black/brown streaks, and then form pseudo-networks or rhomboidal structures. The finding of annular-granular structures partially surrounding a single hair follicle may be the earliest recognizable dermatoscopic feature of an LM and may help clinicians diagnose facial LMs earlier.

In Situ and Very thin Melanomas (< 0.75 mm) are Similarly and Commonly Recognizable

Aims and Background

Recent data have suggested that cutaneous melanoma in situ can be clinically recognized in most cases by its features, which resemble those of early invasive melanoma. The aim of the study was to verify whether the diagnostic sensitivity of melanoma in situ is actually equivalent to that of early invasive melanoma.

Methods

We retrospectively reviewed the clinical diagnosis of 274 consecutive cutaneous melanoma <0.75 mm thick. The series consisted of 84 in situ and 190 invasive lesions.

Results

The clinical diagnosis of melanoma was performed in 62% (52/84) of cases of in situ melanoma and in 68% (130/190) of the cases of invasive melanoma. The differences were not statistically significant.

Conclusions

Our results show that cutaneous melanoma can be clinically diagnosed at a very early stage. In situ and very thin melanomas (< 0.75 mm) are similarly recognizable.

Delineating margins of lentigo maligna using a hyperspectral imaging system

Lentigo maligna (LM) is an in situ form of melanoma which can progress into invasive lentigo maligna melanoma (LMM). Variations in the pigmentation and thus visibility of the tumour make assessment of lesion borders challenging. We tested hyperspectral imaging system (HIS) in in vivo preoperative delineation of LM and LMM margins. We compared lesion margins delineated by HIS with those estimated clinically, and confirmed histologically. A total of 14 LMs and 5 LMMs in 19 patients were included. HIS analysis matched the histo-pathological analysis in 18/19 (94.7%) cases while in 1/19 (5.3%) cases HIS showed lesion extension not confirmed by histopathology (false positives). Compared to clinical examination, HIS defined lesion borders more accurately in 10/19 (52.6%) of cases (wider, n = 7 or smaller, n = 3) while in 8/19 (42.1%) cases lesion borders were the same as delineated clinically as confirmed histologically. Thus, HIS is useful for the detection of subclinical LM/LMM borders.

[A Case of Delayed Dia-gnosis of Acral Lentiginous Melanoma]

BACKGROUND

Melanoma is a malignant skin disease. The tumor development is caused by an uncontrollable proliferation of melanocytes. The most common occurrence is on the skin, but melanoma may also develop on the mucous membrane, meninges, and eyes. Some melanomas develop from melanocytic nevus. Acral lentiginous melanoma occurs on palms, feet, fingers and under nails, and is the most common type of melanoma for phototype VI. The most important factor for successful treatment of malignant melanoma is an early detection, excision of the primary tumor and histological staging. Surgical treatment of an early-stage melanoma is a key to successful therapy; however, many patients (mostly men) do not seek medical attention before it istoo late.

CASE REPORT

This case study presents a 59-year-old patient, who suffers from white coat syndrome and whose finger was amputated for alleged gangrene. Subsequently, brownish black nodules appeared across his arm. Histological examination proved metastases of malignant melanoma. It was only at this phase, when the patient admitted a nevus at the tip of his amputated finger, from which ulceration and gangrene gradually emerged.

CONCLUSION

This case demonstrates a combination of multiple unfavorable factors, which led to delayed diagnosis and therapy.

[Lentigo maligna: a diagnostic and therapeutic challenge]

Lentigo maligna is an early type of melanoma which appears in sun damaged skin. The clinical diagnosis as well as the pathological diagnosis are a challenge to the clinician and the pathologist since atypical proliferation of melanocytes is a common finding in chronically sun exposed skin. The use of a dermatoscope and in vivo reflectance confocal microscopy as diagnostics aids can make the clinical diagnosis more accurate. Mohs micrographic surgery has become the standard of care, if available, for lentigo maligna.

[Clinical utility of reflectance confocal microscopy for the non-invasive diagnosis of lentigo maligna melanoma]

BACKGROUND

Lentigo maligna melanoma (LMM), a melanoma subtype that arises on sun-damaged facial skin, is difficult to diagnose clinically. Patients and physicians are reluctant to perform unnecessary facial biopsies. Reflectance confocal microscopy (RCM) is a novel technique for non-invasive skin imaging at cellular-level resolution. RCM increases the accuracy of melanoma diagnosis.

AIMS

To describe the diagnostic utility of RCM in cases of clinically and dermatoscopically equivocal pigmented skin lesions suspicious for LMM.

METHODS

This is a retrospective case series derived from the population of patients undergoing periodic skin cancer screening at a tertiary hospital clinic that specializes in skin cancer diagnosis. All patients consented to RCM imaging as an ancillary test prior to the decision on performing a biopsy in the facial lesion.

RESULTS

We report on four patients who presented clinically and dermatoscopically equivocal pigmented skin lesions in the head and neck region, with differential diagnosis of LMM. Furthermore, in two patients, a prior incisional biopsy indicated a benign diagnosis upon histopathological analysis. In all cases, RCM examination showed specific criteria for LMM. The RCM diagnosis of LMM allowed direct referral for excisional surgery in three patients. In another patient, RCM findings guided incisional biopsy-site selection to a focus that revealed histopathology clear-cut criteria for LMM.

CONCLUSIONS

RCM is a very useful adjunct to the non-invasive diagnosis of LMM.

Incidence of lentigo maligna in Olmsted County, Minnesota, 1970 to 2007

BACKGROUND

The incidence of lentigo maligna (LM) may be increasing, but no population-based epidemiologic studies have been performed to our knowledge.

OBJECTIVE

We sought to determine the incidence of LM in Olmsted County, Minnesota, along with overall and recurrence-free survival.

METHODS

Using the Rochester Epidemiology Project, we identified all adult residents of Olmsted County, Minnesota, with a first lifetime diagnosis of LM between 1970 and 2007. Medical records were reviewed to determine demographic, clinical, and surgical data, and incidence and survival were calculated.

RESULTS

Among 145 patients identified, median (range) age at diagnosis of LM was 70 (33-97) years. Treatment changed over time, with Mohs micrographic surgery becoming available after 1986. No patients died of LM; 5 had local recurrence. Estimated local recurrence-free survival at 5, 10, 15, and 20 years after diagnosis was 98%, 96%, 92%, and 92%, respectively. Overall age- and sex-adjusted incidence of LM among adults was 6.3 per 100,000 person-years, increasing from 2.2 between 1970 and 1989 to 13.7 between 2004 and 2007.

LIMITATIONS

Retrospective study design and homogeneous population are limitations.

CONCLUSION

The incidence of LM increased significantly among residents of Olmsted County, Minnesota, over an extended time frame, with incidence being significantly higher among men than women and increasing with age.

Melanoma--clinical, dermatoscopical, and histopathological morphological characteristics

Melanoma is one of the most malignant skin tumors with constantly rising incidence worldwide, especially in fair-skinned populations. Melanoma is usually diagnosed at the average age 50, but, nowadays is also diagnosed more frequently in younger adults, and very rarely in childhood. There is no unique or specific clinical presentation of a melanoma. The clinical presentation of melanomas varies depending on the anatomic localization and the type of growth, i.e., the histopathological type of the cancer. There are four major histopathological types of melanoma--superficial spreading melanoma, nodular melanoma, lentigo maligna melanoma, and acral lentiginous melanoma. Although dermatoscopy is a very useful tool in early melanoma detection, dermatoscopical features of melanomas are also variable. Therefore, experience and education in dermatoscopy is crucial in the evaluation of skin tumors. Differential diagnosis of melanomas includes a wide range of benign and malignant skin lesions, due to their clinical presentation and resemblance to various dermatological entities. In this review we present the most important aspects of clinical, dermatoscopical, and histopathological features of melanomas.

Lentigines, laser, and melanoma: a case series and discussion

Solar lentigines are considered one of the earliest signs of photoaging and are an extremely common cosmetic complaint. Successful removal of these lesions can be achieved with laser and non-laser light sources, and is one of the most frequently performed cosmetic procedures in laser centers. Distinguishing a benign lentigo from other pigmented lesions can sometimes be challenging, even for a trained dermatologist. We report a series of three patients who presented to our laser center within 2 months of one another for cosmetic removal of pigmented lesions that were found to be melanoma. One patient was referred by another dermatologist, one by a physician family member, and the other presented on his own. These cases highlight the need for careful evaluation of pigmented lesions prior to laser treatment, regardless of the source of the referral. In this article, we will review the diagnostic and treatment differences between lentigines and their malignant counterparts, and examine the role of laser in both.

Lentigo maligna melanoma--the review

Lentigo maligna melanoma (LMM) is a slowly growing tumor of elderly white population. It typically develops on chronically sun-exposed skin of the head and neck area which indicates that the cumulative exposure to the UV radiation has crucial role in the development of LMM. Precursor lesion is lentigo maligna (LM) which commonly presents as an irregular brownish pigmented macular lesion persisting for years. Women are affected more often as men by LMM, with the average age of over 60 years. The age of onset has dropped over the past years and this tumour is nowadays also diagnosed in 40-year-old individuals. However, the incidence rate increases with age and peaks in the seventh and eighth decades of life. The prognosis for invasive lentigo maligna melanoma does not differ from that for other histogenetic types of melanoma after controlling for tumour thickness. The diagnosis and treatment of LMM remain challenging. In this presentation, we review the epidemiology, clinical presentation, histopathology, and treatment of LMM.

Lentigo maligna: current concepts in diagnosis and management

Lentigo maligna (LM) is a cutaneous malignancy with increasing incidence and significant risk of morbidity. Early diagnosis of LM requires a high index of suspicion for the often subtle atypical signs of pigmented lesions on sun-damaged skin. A variety of treatment options are available to the physician. Surgical options include simple excision and margin-control techniques such as staged excision and Mohs micrographic surgery. Tissue may be embedded vertically or en face, and processed as frozen or paraffin-embedded sections. Destructive options include radiotherapy, cryotherapy, curettage, and electro-destruction. Topical therapy may be appropriate in selected cases; immunotherapy with topical imiquimod may have advantages over other topical agents. The opportunity for curative therapy is maximized by surgical treatment. Margin-control surgery offers the highest cure rate while minimizing loss of normal tissue.

Confocal microscopy of skin cancers: translational advances toward clinical utility

Recent advances in translational research in and technology for confocal microscopy of skin cancers, toward clinical applications, are described. Advances in translational research are in diagnosis of melanoma in vivo, pre-operative mapping of lentigo maligna melanoma margins to guide surgery and intra-operative imaging of residual basal cell carcinomas to guide shave-biopsy. Advances in technology include mosaicing microscopy for detection of basal cell carcinomas in large areas of excised tissue, toward rapid pathology-at-the-bedside, and development of small, simple and low-cost line-scanning confocal microscopes for worldwide use in diverse primary healthcare settings. Current limitations and future opportunities and challenges for both clinicians and technologists are discussed.

Lentigo maligna occurring in a patient with the past history of laser therapy

A 70-year-old Japanese woman visited our clinic with a pigmented patch on her face from her upper lip to under her nose following laser therapy 15 years ago. Physical examination revealed an asymmetrical dark brown macule with a clear border along with irregular black dots measuring 20 mm. A biopsy specimen showed some irregular-sized atypical melanocytes with deep-colored nuclei on staining. There were observed on the basal layer and a few of them in the prickle-cell layer only in the epidermis. We diagnosed this case as lentigo maligna (LM). Total resection and reconstruction with the Abbe flap were carried out. We searched previous literature for reports on laser therapies resulting in LM and determined the following: (1) there were no reports indicating that laser therapy is one of the causes of LM, (2) judging from invalidity of treatment or recurrence of the condition, laser therapies were considered ineffective for LM treatment, and (3) the numbers of patients undergoing laser therapies, who were not diagnosed with LM, were increasing.

Lentigo maligna/lentigo maligna melanoma: current state of diagnosis and treatment

BACKGROUND

Lentigo maligna (LM) is a subtype of melanoma in situ that typically develops on sun-damaged skin. Presentation may be quite subtle and delayed diagnosis is common. Clinical margins are often ill defined. Histologic evaluation can be difficult due to the widespread atypical melanocytes that are present in the background of long-standing sun damage. Recurrence following standard therapies is common.

OBJECTIVE

To review the clinical features, histopathology, and treatment options for LM. Emphasis is placed on recent advances in the treatment of LM.

METHODS AND MATERIALS

Literature review.

RESULTS

The estimated lifetime risk of LM progressing to LM melanoma is 5%. Standard excision of LM with 5 mm margins is insufficient in 50% of cases. The recurrence rate with standard excision ranges from 8 to 20%. Mohs surgery and staged excision may offer better margin control and lower recurrence rates (4-5%). Estimates of recurrence rates following nonsurgical therapies such as cryosurgery, radiotherapy, electrodessication and curettage, laser surgery, and topical medications range from 20 to 100% at 5 years.

CONCLUSIONS

Adequate treatment of LM requires a comprehensive knowledge of the diagnostic features, histopathology, and treatment options. Surgical modalities with meticulous evaluation of tissue margins appears to offer the lowest rates of disease recurrence.

Contiguous lesions in lentigo maligna

BACKGROUND

Determining the best biopsy technique for a suspected lentigo maligna can be challenging. Because complete excisional biopsy is rarely practical, the physician is left to choose an appropriate area to biopsy. Sampling error can have devastating consequences, especially if the biopsy demonstrates a pigmented lesion that was considered in the clinical differential diagnosis. The presence of a solar lentigo, pigmented actinic keratosis, or reticulated seborrheic keratosis could mislead the pathologist and clinician to the erroneous conclusion that the incisional specimen is representative of the whole, and that no lentigo maligna is present.

OBJECTIVE

We have often observed the presence of a contiguous pigmented lesion adjacent to lentigo maligna. The current study was designed to determine how frequently this phenomenon occurs.

METHODS

We studied Mohs debulking specimens of lentigo maligna, and broad shave biopsy specimens of pigmented lesions on heavily sun-damaged areas of the skin proven to be lentigo maligna.

RESULTS

Contiguous pigmented lesions were present in 48% of the specimens. The most common lesion was a benign solar lentigo (30%), followed by pigmented actinic keratosis (24%).

CONCLUSION

Recognition of this phenomenon may prevent misdiagnosis of lentigo maligna related to sampling error.

Lentiginous melanoma: a histologic pattern of melanoma to be distinguished from lentiginous nevus

Atypical lentiginous melanocytic proliferations in elderly patients continue to pose a diagnostic dilemma with lesions variably categorized as dysplastic nevus, atypical junctional nevus, melanoma in situ (early or evolving) and premalignant melanosis. We present pigmented lesions from 16 patients (seven male and nine female) and with the exception of one case, all were older than 50 years of age. The anatomical sites included trunk (7), head and neck (6) and upper extremity (3). The clinical diagnosis was variable and included lentigo maligna, atypical nevus, pigmented basal cell carcinoma, seborrheic keratosis and lentigo. The initial biopsies mimicked lentiginous nevus or dysplastic nevus and were characterized by a lentiginous proliferation of melanocytes at the dermoepidermal junction both as single cells and as small nests with areas of confluent growth, extending to the edges of the biopsy. The retiform epidermis was maintained and pagetoid spread of melanocytes was not prominent in hematoxylin- and eosin- stained sections. Dermal fibrosis was variably present and the melanocytic proliferation demonstrated cytological atypia. The subsequent re-excisions demonstrated similar atypical melanocytic proliferation occurring over a broad area flanking the prior biopsy sites. The diagnosis of melanoma was more easily recognized in the complete excision specimens. Immunohistochemical stains for Mitf and Mart-1 highlighted the extent of the basalar melanocytic proliferation as well as foci of pagetoid spread by melanocytes. Familiarity with this pattern of early melanoma should facilitate proper classification of lentiginous melanocytic proliferations in biopsies from older adults.

Utility of the Wood's light: five cases from a pigmented lesion clinic

We demonstrate the utility of the Wood's light in a practice that specializes in the evaluation of pigmented lesions. The Wood's light assisted the physician in locating the site of a completely regressed primary cutaneous melanoma, determining the clinical borders of a lentigo maligna melanoma, differentiating between agminated naevi and a naevus spilus and detecting the recurrence of pigmentation after the excision of a dysplastic naevus, and also proved useful in monitoring a large segmental speckled atypical lentiginous naevus for change. Despite the availability of many 'high-tech' imaging and diagnostic devices designed to evaluate skin lesions, the relatively simple Wood's lamp continues to be of great value. We encourage physicians not to abandon the use of the Wood's light in their clinical practice.

Cutaneous Lesions: Benign and Malignant

This article reviews the clinical characteristics, histology, biologic behavior, and recommended treatment for several benign and malignant lesions that may arise on the head and neck. Nevus sebaceus and congenital melanocytic nevus are two benign lesions that can present at a size of several centimeters. Surgical excision may be considered for cosmetic purposes and to reduce the small risk for the development of malignancy within each lesion. Basal and squamous cell carcinoma, lentigo maligna and lentigo maligna melanoma, dermatofibrosarcoma protuberans, and Merkel cell carcinoma are malignant lesions for which surgical excision is the recommended treatment. Local flap reconstruction may be used to address the surgical defects resulting from excision of these benign and malignant conditions.

A comparison of dermoscopic features among lentigo senilis/initial seborrheic keratosis, seborrheic keratosis, lentigo maligna and lentigo maligna melanoma on the face

Clinical differentiation of facial lentigo senilis/initial seborrheic keratosis (LS/ISK), seborrheic keratosis (SK), lentigo maligna (LM), and lentigo maligna melanoma (LMM) can be difficult. Dermoscopy improves the diagnoses in pigmented skin lesions (PSLs), but it is not helpful for the sun-exposed face because of the flat rete ridges without network-derived features. Therefore, development of new diagnostic criteria for this particular localization is a current issue of dermatology. In this retrospective study, dermoscopic slides of facial pigmented skin lesions of 66 patients referred to two clinics in Turkey were evaluated. Our aim was to determine the reliability of dermoscopy in the differentiation of these entities. The facial PSLs of 66 patients (34 males and 32 females) (median age: 58.2) were photographed with a Dermaphot (Heine, Hersching, Germany) over a five year period from November of 1995 to May of 2000. All of the dermoscopic slides were analysed according to 27 dermoscopic criteria developed by Schiffner et al. This data set contained 22 histologically proven malignant (14 LM, 8 early LMM) and 44 benign (18 SK, 26 LS/ISK) PSLs. In general, asymmetric pigmented follicular openings, dark streaks, slate-gray streaks, dark globules, slate-gray globules, dark dots, dark rhomboidal structures, light brown rhomboidal structures, dark homogeneous areas and dark pseudonetworks were statistically significant for malignant growth. On the other hand, milia-like cysts, pseudofollicular openings, cerebriform structures, light brown globules, light brown dots, light brown homogeneous areas, yellow opaque homogeneous areas, and light brown pseudonetworks were statistically significant for benign growth. This research emphasizes that dermoscopic features on the face differ from criteria used in other locations of the body. Analysis of the data suggests that dermoscopy can be used in the differentiation of LS/ISK, SK, LM and LMM from each other.

Dermoscopy for early detection of facial lentigo maligna

Up until now, only lesions selected on the basis of their clinical atypia or which appear equivocal on naked eye examination have been shown to benefit from the use of dermoscopy. In our experience, dermoscopic evaluation of lesions located on the face may require a different approach, as a histopathological diagnosis of malignancy is not uncommon in clinically trivial lesions (i.e. lesions lacking the ABCD criteria for clinical suspicion). Moreover, at this site dermoscopy reveals specific criteria according to the particular histological architecture shown by sun-damaged skin. We report four cases of lentigo maligna (LM) of the face whose identification depended on dermoscopic examination which was performed routinely on all facial lesions, as the lesions did not show ABCD clinical criteria for malignancy. In our experience, the identification of early signs of malignancy by dermoscopy may indicate the excision of LM at an early phase, before the lesion is associated with the ABCD signs of melanoma. Dermatologists should avoid the mistake of immediately excluding a diagnosis of malignancy when examining an ABCD-negative pigmented skin lesion of the face.

Management of lentigo maligna

Lentigo maligna melanoma is a melanoma in situ on sun-damaged skin. It is a variably brown-pigmented flat patch on the head or neck of elderly patients. Its growth is generally slow, but it can become an invasive form of melanoma. Multiple reported treatment options are reviewed. Wide-margin Mohs micrographic surgery with peripheral permanent pathologic confirmation of a clear margin is recommended as treatment of choice.