Lentigo Maligna: Clinical Presentation and Appropriate Management

Figures & data

Figure 1 Lentigo maligna(LM)/LM melanoma (LMM) clinical presentations. (A) LM presenting as a large irregularly pigmented patch in the forehead with central regression and ill-defined borders. (B) LM arising on the right cheek clinically simulating a seborrheic keratosis. (C) Large LM occurring on the nose and surrounded by chronically sun damaged skin. (D) Light brown patch with ill-defined borders in a fair-skinned individual corresponding to a LMM that can clinically be easily mistaken for solar lentigo. (E) Extrafacial LMM affecting the upper back presenting as an isolated large homogeneous brown patch with irregular borders. (F) Nodular melanoma arising on a previous LM (note the brown pigment surrounding the nodule corresponding to the in situ component).

Table 1 Lentigo Maligna (LM)/LM Melanoma (LMM) Differential Diagnosis: Clinical Presentation and Dermoscopy

	Clinical Presentation	Dermoscopy
LM/LMM^Citation47,Citation151	Appears on chronically sun damaged skin (predominantly head and neck) Pigmented macule or patch with ill-defined borders	Polygons/rhomboids/zig-zag pattern (angulated lines) Annular-granular pattern Asymmetric pigmented follicular openings Circle within a circle
Solar lentigo^Citation152	Multiple lesions Brown papule/plaque Darker areas can be elevated or verrucous	Moath-eaten borders Pseudonetwork Comedo-like openings Diffuse opaque-brown pigmentation Lightbrown fingerprint-like structures Milia-like cysts
Seborrheic keratosis^Citation153^–^Citation155	Appears on the torso and face Multiple lesions Sharply demarcated brown-to-black papules/plaques Can have verrucous/rough texture	Milia-like cysts Comedo-like openings Hairpin vessels Sharp demarcation and moth-eaten borders Fat fingers
LPLK^Citation156,Citation157	Solitary lesion Slightly reddish papule/plaque with smooth or verrucous surface Appears on sun-exposed trunk and upper extremities	Localized or diffuse annular granular pattern
Pigmented AK^Citation49,Citation151	Predominantly on the face Scaly and rough surface	Annular pattern Grayish short strikes and granules Pseudoreticular structures Grayish brown dots and globules White and evident follicles Scales Brown-to-gray rhomboidal lines (without invading follicular openings) Background erythema

Abbreviations: LM/LMM, Lentigo maligna/lentigo maligna melanoma; LPLK, lichen planus like keratosis; AK, actinic keratosis.

Figure 2 Lentigo maligna(LM)/LM melanoma (LMM) dermoscopic findings. (A) Facial LM with an annular-granular pattern consisting of brown dots scattered around adnexal openings. (B) LM showing a large blotch with the blue-black sign. (C) LM on the scalp with follicle obliteration and central regression (gray peppering or granularity). (D) Facial LM with an annular-granular pattern around adnexal openings and follicle obliteration. (E) Brown lines coalescing to form rhomboids (angulated lines) around adnexal ostial openings at the periphery of this LM. Also, an asymmetric distribution of pigment surrounding the follicular openings can be seen. (F) Extrafacial LM with presence of network and atypical dots. Note the absence of adnexal openings in extrafacial skin.

Figure 3 Schiffner progression model fo LM/LMM. Initially asymmetric pigmentation and dots around the follicle are seen (A), which later evolve to rhomboidal structures (B) and finally form homogeneous pigmented areas and cause obliteration of the follicular openings (C). Adapted with permission from Dermoscopedia (https://creativecommons.org/licenses/by-nc-sa/4.0/).¹⁵⁸

Figure 4 Reflectance confocal microscopy images of a lentigo maligna. The epidermis (depth ~50 µm) shows numerous pleomorphic pagetoid cells composed of large round cells (arrowheads, A) as well as dendritic cells (star, A), which can invade the hair follicles (star, B). At the dermal-epidermal junction (depth ~150 µm), one can also identify disarrangement of the basal layer as well as large plump cells which correlate with melanophages (arrowhead, B), and junctional thickenings than can radiate from the hair follicles adopting a medusa head-like () structure (arrowhead, C), or a mitochondria-like structure (asterisk, D). (white scale bars: 250 µm).

Table 2 In vivo Confocal Features for LM Diagnosis

Guitera et al, 2010 (LM Score)^Citation59

Major features (2 points each) Nonedged dermal papillae Round and large pagetoid cells (>20 microm) Minor features (1 point each) More than three atypical cells at the dermoepidermal junction in five images Follicular localization of pagetoid cells Nucleated cells within the dermal papillae Minor negative feature (1 point) Broadened honeycomb pattern

Champin et al, 2014^Citation65

Single large round cell or large dendritic cell

Yélamos et al, 2017^Citation66

Atypical dendritic cell (any size) continuing from the LM trailing edge.

Figure 5 (A) Histological pictures of lentigo maligna. Lentigo maligna in the radial growth phase. Solar elastosis (arrow), a patchy lymphocytic infiltrate and melanophages are seen in the dermis (+ sign). An atrophic epidermis (asterisk) and an increased density of melanocytes along the dermal-epidermal junction can be seen, some of them with variable nuclear atypia (arrowheads). Hematoxylin-eosin stain10x. (B) Extrafacial lentigo maligna on chronically sun-damaged skin. Atrophic epidermis (asterisk), prominent solar elastosis (arrow) and increased density of junctional pleomorphic melanocytes forming asymmetric nests with pagetoid growth of single melanocytes (arrowheads). Dermal inflammatory infiltrate with melanophages (+ sign). Hematoxylin-eosin stain10x.

Table 3 Evidence-Based Recommendations for Lentigo Maligna (LM)

	Strength of Recommendation	Level of Evidence
Complete surgical removal of LM with 5- to 10-mm clinical margins is the preferred management, when possible	C	III
Peri-operative reflectance confocal microscopy margin assessment should be considered when available	C	III
Mohs micrographic surgery is recommended for LM when available	B	II/III
Topical imiquimod 5% cream as second-line treatment for LM when surgery is not possible at the outset (primary setting) or when optimal surgery has been performed (adjuvant setting)	B	II/III
Radiotherapy as a second-line therapy for nonsurgical candidates	C	II/III
Superficial brachytherapy is not recommended	C	III
Cryotherapy is not recommended	C	III
Laser therapy is not recommended	C	III

Notes: Adapted from Swetter et al⁸¹ and Robinson et al.⁹⁷ Strength of Recommendations. A. Recommendation based on consistent and good quality patient-oriented evidence. B. Recommendation based on inconsistent or limited-quality patient-oriented evidence. C. Recommendation based on consensus, opinion, case studies, or disease-oriented evidence. Level of Evidence. I: Good-quality patient-oriented evidence (ie, evidence measuring outcomes that matter to patients: morbidity, mortality, symptom improvement, cost reduction, and quality of life). II. Limited-quality patient-oriented evidence. III. Other evidence, including consensus guidelines, opinion, case studies, or disease-oriented evidence (ie, evidence measuring intermediate, physiologic, or surrogate end points that may or may not reflect improvements in patient outcomes).

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