Extrafacial lentigo maligna melanoma: analysis of 71 cases and comparison with lentigo maligna melanoma of the head and neck

Lentigo maligna: a comprehensive review on diagnosis and treatment

Lentigo maligna (LM), a form of melanoma in situ, and LM melanoma (LMM), its invasive counterpart, exhibit distinctive epidemiology, risk factors, and clinical features compared to other melanoma subtypes. Notably, LM occurs on chronically sun-damaged skin presenting as a slow-growing, ill-defined patch which makes it difficult to diagnose and to treat. Additionally, while LM generally presents a favourable prognosis, it can also lead to dermal invasion and behave similarly to other melanomas with the same Breslow thickness. Hence, surgery continues to be the cornerstone treatment. Wide excisions are often necessary, but challenges arise when these lesions manifest in cosmetically sensitive regions, limiting the feasibility and desirability of large excisions. Specialized approaches, including margin-controlled surgery and image-guided treatment with reflectance confocal microscopy, have been developed to address these issues. Other non-surgical treatments such as cryosurgery, imiquimod, radiotherapy, or photodynamic therapy, may also be used but commonly present with recurrent/persistent disease. Herein we comprehensively review the existing literature on the management of LM/LMM, and discus the potential new advances on managing this challenging skin cancer.

[Translated article] Update on Lentigo Maligna: Diagnostic Signs and Treatment

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.

Lentigo Maligna

Lentigo maligna (LM) is a melanocytic neoplasm found on chronically sun-exposed areas of the body, particularly the head and neck. It commonly occurs in the elderly and has been referred to as a "senile freckle." It has also been termed "Hutchinson melanotic freckle," as it was first described by John Hutchinson in 1892. LM is defined as melanoma in situ and thus confined to the epidermis. LM lesions that invade the dermis are termed lentigo maligna melanoma, 1 of the 4 subtypes of malignant melanoma.

Lentigo Maligna: Clinical Presentation and Appropriate Management

Lentigo maligna (LM) is a type of melanoma in situ that has distinctive characteristics regarding epidemiology, risk factors and clinical features. In addition, LM has a potential to progress to an invasive tumor with potentially aggressive behavior: lentigo maligna melanoma (LMM). Overall, LM has a very good prognosis, whereas LMM has the same prognosis as other invasive melanomas with similar Breslow thickness. LM/LMM represents a challenging entity not only regarding the diagnosis but also regarding the management. Diagnostic criteria are not well established, and there is an overlap of clinical, dermoscopic and pathological features with other benign pigmented skin lesions such as lentigines, pigmented actinic keratoses or macular seborrheic keratoses. LM/LMM's common appearance within photodamaged skin makes lesion border identification difficult. Wide excisions are often required, but since LM/LMM typically appears on cosmetically sensitive areas such as the face, sometimes large excisions are not possible nor desirable. In this sense, specialized approaches have been developed such as margin-controlled surgery or image-guided treatment using reflectance confocal microscopy. Other treatments for LM such as cryosurgery, imiquimod, radiotherapy or photodynamic therapy have been proposed, although recurrence/persistence is common. The current manuscript reviews extensively the published data regarding the diagnosis, treatment and management of both complex entities LM and LMM.

Lentigo Maligna - Not Always a Face and Neck Disease of the Elderly

INTRODUCTION

Lentigo maligna (LM) is a rare form of in situ melanoma, frequently seen as a large patch in elderly patients. The aim of this study was to assess clinical and dermoscopic features of LM.

MATERIAL AND METHODS

A retrospective study of LM patients presenting to our center between July 2007 and July 2017 was performed. Demographic data, anatomical location, laterality, diameter, Clark level, Breslow stage, "ABCD" signs and dermoscopic features were registered. Facial versus extrafacial LM were compared.

RESULTS

We found 21 LM, of which 12 had an extrafacial location and 9 a facial location. Half of the extrafacial lesions were located on an upper limb. The median age at diagnosis was 63 years (ranging from 38 to 84 years). Most LM cases were female (16/21) with phototype II (13/21). More than half of the patients (11/21) had a history of a skin neoplasm or actinic keratosis. The median diameter found was 6 mm (interquartile range = 4.5 mm), ranging from 1 to 15 mm. Five lesions were invasive (median Breslow depth of 0.2 mm), and 4 of them were extrafacial.

DISCUSSION

In this study LM was more frequently found in an extrafacial location and as a small patch with a 6-mm diameter medium. The epidemiology of LM/LM melanoma might be changing. Full body examination and dermoscopy are of the utmost importance for the diagnosis. Dermatologists should be aware and search for small lesions outside the face and neck, particularly in middle-aged female patients with photo-damaged skin.

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.

Extrafacial Lentigo Maligna: A Report on 14 Cases and a Review of the Literature

Lentigo maligna is the most common form of in situ melanoma. It is most often found on the head and neck, and its clinical and dermoscopic features in this location have been extensively described in the literature. We present a series of 14 patients diagnosed with extrafacial lentigo maligna and lentigo maligna melanoma at Hospital General de Valencia and Hospital de Manacor in Spain, and describe the clinical, dermoscopic, and histologic features observed. Most of the melanomas were located on the upper limbs; the next most common locations were the trunk and the lower limbs. The dermoscopic patterns were consistent with facial lentigo maligna and superficial spreading melanoma. Extrafacial lentigo maligna is uncommon. It has similar clinical and histologic features to facial lentigo, but dermoscopy may show a mix of patterns typically seen in lentigo maligna and superficial spreading melanoma. This difference in dermoscopic features is essentially due to anatomical differences between skin on the face and on other parts of the body.

Is head and neck melanoma a distinct entity? A clinical registry-based comparative study in 5702 patients with melanoma

BACKGROUND

The head and neck region is more heavily exposed to ultraviolet (UV) radiation than any other body site. Therefore, cutaneous malignant melanoma (CMM) of the head and neck area is proposed to have notable differences from melanoma at other body sites regarding clinicopathological features and survival of patients.

OBJECTIVES

The present retrospective study based on clinical registry data aims to compare clinical features and prognostic factors of head and neck melanoma (HNM) vs. melanoma at other anatomical regions (MOR) in order to detect differences which may be associated to the mode of sun exposure.

METHODS

The clinical records and histopathological findings of 844 patients with clinical stage I and II invasive HNM were compared with the data of 4858 patients with MOR. Survival analysis was performed using the Kaplan-Meier estimate, and the multivariate Cox proportional hazard model was used to evaluate independent prognostic factors.

RESULTS

Melanoma density was clearly higher for HNM than for MOR: this was particularly true for the face, where it was elevated by a factor of 2.6. There was a higher male/female ratio in patients with HNM and they were significantly older than patients with MOR (P < 0.0001). Breslow tumour thickness did not differ between HNM and MOR. However, CMMs at the scalp were significantly thicker and to a higher degree ulcerated. Concerning clinicopathological CMM subtypes, there was an increased proportion of lentigo maligna melanoma among HNM and of nodular melanoma in the scalp and neck regions. Excision margins were narrower and the rate of complete primary excision was lower in HNM than in MOR. Overall, there was no significant statistical difference in cumulative 10-year survival rates according to Kaplan-Meier estimates among patients with HNM (84.6%) and MOR (87.8%). Tumour thickness turned out to be the variable with the highest prognostic impact followed by ulceration in both HNM and MOR.

CONCLUSIONS

In relation to the skin surface significantly more CMMs were found in the head and neck area than in other anatomical regions. This might indicate, but does not prove, that UV exposure promotes the development of CMM. Although HNM showed specific clinicopathological features, prognosis remained unaffected. Thus HNM seems not to be a distinct subtype of CMM.

Follicular malignant melanoma: a variant of melanoma to be distinguished from lentigo maligna melanoma

Follicular malignant melanoma can be regarded as a rare and unique presentation of melanoma. It is characterized by a deep-seated follicular structure in which atypical melanocytes extend downward along the follicular epithelium and permeate parts of the follicle as well as the adjacent dermis. The clinical diagnosis of follicular malignant melanoma may be difficult because the tumor mostly resembles a comedo or a pigmented cyst. We studied five cases of follicular malignant melanoma in which the patients were between 61 and 82 years old. Three lesions were localized on the nose, one on the cheek, and one on the back of the neck. Clinically, all five cases measured distinctly less than 0.5 cm in size. While lentigo maligna is traditionally known as a pigmented macule in actinically damaged skin that gradually evolves in a slow process before invasive growth, three follicular malignant melanomas had developed in relatively short timeframes of 9 months to 1 1/2 years. In all five cases the inconspicuous clinical appearance did not herald a malignant melanoma with invasive growth. Follicular malignant melanoma underlines the importance of a correct excision technique with subsequent histologic workup and diagnosis. Superficial shave excision or even laser treatment in these specific cases may lead to a fatal prognosis for the patient.

Management of lentigo maligna and lentigo maligna melanoma: Seminars in surgical oncology

Lentigo maligna (LM) and lentigo maligna melanoma (LMM) represent a character, histogenetic subclass of melanocytic malignancies. They often present with a prolonged phase of slow growth but once invasion has occurred, the prognostic features are identical to all other melanomas. These lesions occur primarily on the head and neck where they evolve from areas of pigmented staining to the more typical features identifiable with malignant melanomas on other skin surfaces. The treatment options and recent advances in management are reviewed.

Pitfalls in the diagnosis of malignant melanoma: findings of a risk management panel study

The misdiagnosis of melanoma is a major cause of malpractice claims involving pathologists and dermatologists. A detailed analysis of individual surgical pathology and cytology claims (excluding Pap smears) reported to The Doctors Company from 1995 through 2001 revealed that 46 of 362 claims (13%) involved the misdiagnosis of melanoma; 70% of these claims were for false-negative diagnoses. Melanoma claims were second only to claims involving breast biopsy. A Melanoma Risk Management Panel of expert dermatopathologists was convened to discuss recurrent "problem areas" identified by the author in claims reviewed from 1998 through 2001. The purpose was to devise useful strategies that pathologists and dermatologists could use in their practices to reduce the risk of diagnostic error and/or patient mismanagement when dealing with melanocytic lesions. The panel's findings and recommendations are the subject of this review.

Local recurrence in melanoma in situ: influence of sex, age, site of involvement and therapeutic modalities

BACKGROUND

Melanoma in situ (MIS) occurs on various body sites, in various age groups, and is managed by a variety of treatment modalities. Despite early treatment, recurrences may be encountered.

OBJECTIVES

To evaluate the influence of sex, age, body site and treatment modalities on recurrence rate in MIS. Methods Histologically confirmed cases of MIS from our dermatopathological database (n = 1351) from 1990 to 2000 were statistically analysed with respect to epidemiological characteristics, treatment modalities and outcome. Treatment modalities of the included MIS were evaluated by searching for data in the medical records and histopathological data sheets.

RESULTS

There was a predominance of female patients (60.8%), and of involvement of the head and neck (53.4%). Total excision was performed in 95.9% of all patients; the remainder received cryotherapy, laser therapy or radiotherapy. In 265 patients, no data on definitive treatment were available. Alternatives to total excision were particularly performed in patients with advanced age and with lesions localized on the face. The mean +/- SD 5-year recurrence rate was 6.8 +/- 1.3% for surgically removed lesions, but was 31.3 +/- 8.5% for lesions treated by other modalities (log rank test: P < 0.0001). In a multivariate approach, mode of therapy and site of involvement, but not age, were significant prognostic variables (Cox proportional hazard model: P < 0.01).

CONCLUSIONS

In MIS, treatment modalities other than surgical excision may be used in certain situations, but carry a significantly increased risk of local recurrence.

Ultraviolet-Assisted Punch Biopsy Mapping for Lentigo Maligna Melanoma

Lentigo maligna melanoma (LMM) accounts for a substantial incidence of all locally recurrent melanoma. In addition, the head and neck area accounts for 60% to 90% of all LMMs, which has important functional and cosmetic implications. The difficulty in the identification of the true borders of LMM may account for the high incidence of local recurrence. The purpose of this study was to evaluate the efficacy of ultraviolet-assisted punch biopsy mapping to identify clear margins using identified, 2-mm circumferentially arranged punch biopsies at the junction of the pigmented and nonpigmented borders. A retrospective chart review of 20 patients with biopsy-confirmed LMM of the head and neck was performed. Using ultraviolet identification, 2-mm circumferentially arranged biopsy specimens were obtained and sent for formal pathological review, including immunohistochemical staining. The average time for completion of pathological review was 5 to 7 days. If the punch biopsies were positive for lentigo maligna or LMM, punch biopsies were obtained more peripherally. Once clear, margins were obtained and definitive resection was performed. Twenty patients with biopsy-proved LMM were evaluated. Follow-up ranged from 6 months to 3 years (mean follow-up, 1 year). Fourteen patients were cleared after their first series of biopsies, 3 patients required a second series of biopsies, 2 patients required a third session, and 1 patient required a fourth biopsy session. To date, there has been no evidence of recurrence. No patients required reexcision for positive surgical margins. One complication has been local cellulitis of a punch biopsy site requiring a short course of antibiotics. Ultraviolet-assisted punch biopsy mapping of LMM is a safe, well-tolerated, and accurate technique for identifying the true histological margin of LMM. The procedure reduces the need for repeat surgical excisions to obtain clear margins and may decrease the risk for recurrence by mapping accurately the true histological margin.