Subungual melanoma: molecular analysis of 31 cases from early stage to invasive melanoma.

AIMS: The distinction between the benign subungual melanocytic lesions and an early lesion of subungual melanoma (SUM) remains a diagnostic challenge. We evaluated the routine diagnostic utility of array Comparative Genomic Hybridization (aCGH) to detect whole-genome copy number variations (CNV) as well as targeted next-generation sequencing (NGS) in SUM. METHODS AND RESULTS: This retrospective study included 20 cases of in situ SUM and 11 cases of invasive SUM. Analysis by aCGH detected common oncogene amplifications in all but one case of invasive SUM (n = 10) and in all cases of in situ SUM with a melanocyte count (MC) >45/mm (n = 4 true positive) and the average number of CNV was 8.5. Thirteen remaining cases of in situ SUM gave false negative results (n = 13), owing to a lack of sufficient melanocytes to analyse (median MC of 35.35; range: 10.16-39.5). Molecular analysis failed in four cases (three in situ SUM and one invasive SUM) due to insufficient amounts of DNA. Across the whole cohort, the sensitivity of aCGH was 52%, but when adjusting the cutoff to MC >45/mm, the sensitivity was 93%. Targeted NGS was less informative than aCGH analyses in our series of SUM. CONCLUSION: To distinguish malignant from benign lesions, especially in situ SUM versus atypical lentiginous melanocytic proliferations, aCGH analysis should be performed when the MC is above 45 melanocytes per linear millimetre. This pangenomic method can detect oncogene amplifications, as well as a number of CNV >3, which strongly support the diagnosis of malignancy.

Lentigo Maligna and Lentigo Maligna Melanoma of the External Ear: Clinical and Dermoscopic Features of 19 Patients.

External ear lentigo maligna/lentigo melanoma (LM/LMM) represents approximately 1%-4% of all primary cutaneous melanomas. Over the past 20 years, dermoscopy has proven highly effective in early detection of LM/LMM, with recent studies identifying perifollicular linear projections (PLP) as a specific diagnostic criterion for early LM. However, in clinical practice, LM and LMM turn out to be very difficult to distinguish based on dermoscopic findings. Therefore, our retrospective monocentric study aimed to investigate dermoscopic characteristics, as well as the epidemiological and clinical data of 19 patients diagnosed with the external ear (EE) LM/LMM at the Oncologic Dermatology Unit in Bologna. Dermoscopic images were obtained using the FotoFinder Medicam 800HD, and specific criteria validated by the International Dermoscopy Society (IDS) for atypical pigmented facial lesions were assessed. Fisher's exact test was primarily used for statistical comparisons. As results, most of the patients were male (74%) with an average age (± SD) at diagnosis of 69.8 (± 15.1) years old. LMM appeared more commonly observed in elderly patients as compared to LM (mean 71.6 vs. 66.7, p = 0.514), presenting as pigmented macule (89.5%) of the ear lobule (23.9%). A statistically significant difference (p = 0.01) of tumour' diameter between LMM and LM was reported with the first resulting more than twice the size of the latter. Concerning dermoscopic findings, asymmetric pigmented follicles, obliteration of the follicular openings and grey circles were more frequently observed in LMM compared to LM (63.2% vs. 31.6%; 63.2% vs. 26.3%; 47.4% vs. 15.8%, respectively).

Is sentinel lymph node biopsy needed for lentigo maligna melanoma?

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

Real-life practice of reflectance confocal microscopy in France: A prospective multicenter study.

BACKGROUND: Studies demonstrating the potential utility of reflectance confocal microscopy (RCM) have been performed under experimental conditions. OBJECTIVE: To provide an overview of RCM practice in real-life. METHODS: A multicenter, prospective study carried out in 10 university dermatology departments in France. RESULTS: Overall, 410 patients were enrolled. One-half of the patients (48%) were referred by private practice dermatologists. They were referred for diagnosis (84.9%) or presurgical mapping (13%). For diagnosis, the lesions were located on the face (62%), arms and legs (14.9%), and trunk (13.6%), and presurgical mapping was almost exclusively on the face (90.9%). Among those referred for diagnosis, the main indication was suspicion of a skin tumor (92.8%). Of these, 50.6% were spared biopsies after RCM. When RCM indicated surgery, histology revealed malignant lesions in 72.7% of cases. The correlation between RCM and histopathology was high, with a correlation rate of 82.76% and a kappa coefficient of 0.73 (0.63; 0.82). LIMITATIONS: This study was performed in the settings of French tertiary referral hospitals. CONCLUSION: This study shows that in real-life RCM can be integrated into the workflow of a public private network, which enables a less invasive diagnostic procedure for patients.

Perifollicular linear projections: A dermatoscopic criterion for the diagnosis of lentigo maligna on the face.

BACKGROUND: Lentigo maligna (LM) can mimic benign, flat, pigmented lesions and can be challenging to diagnose. OBJECTIVE: To describe a new dermatoscopic feature termed "perifollicular linear projections (PLP)" as a diagnostic criterion for LM on the face. METHODS: Retrospective study on reflectance confocal microscopy and dermatoscopy images of flat facial pigmented lesions originating from 2 databases. PLP were defined as short, linear, pigmented projections emanating from hair follicles. Dermatoscopy readers were blinded to the final histopathologic diagnosis. RESULTS: From 83 consecutive LMs, 21/83 (25.3%) displayed "bulging of hair follicles" on reflectance confocal microscopy and 18 of these 21 (85.7%), displayed PLP on dermatoscopy. From a database of 2873 consecutively imaged and biopsied lesions, 252 flat-pigmented facial lesions were included. PLP was seen in 47/76 melanomas (61.8%), compared with 7/176 lesions (3.9%) with other diagnosis (P < .001). The sensitivity was 61.8% (95% CI, 49.9%-72.7%), specificity 96.0% (95% CI, 92.9%-98.4%). PLP was independently associated with LM diagnosis on multivariate analysis (OR 26.1 [95% CI, 9.6%-71.0]). LIMITATIONS: Retrospective study. CONCLUSION: PLP is a newly described dermatoscopic criterion that may add specificity and sensitivity to the early diagnosis of LM located on the face. We postulate that PLP constitutes an intermediary step in the LM progression model.

Excision margins for melanoma in situ on the head and neck-A single-center 10-year retrospective review of treatment with Mohs micrographic surgery.

BACKGROUND: Although current guidelines recommend a 5 mm surgical margin for the excision of melanoma in situ (MIS), increasing evidence has shown this may be suboptimal to achieve tumor clearance. OBJECTIVE: To evaluate margins required for optimal cure rates with excision of MIS on the head and neck and investigate tumor and/or patient factors in those requiring >5 mm margins to achieve tumor clearance. METHODS: A retrospective chart review was performed on 846 (807 primary and 39 recurrent) MIS cases on the head and neck treated in the authors' dermatologic surgery department over a 126-month (10.5 year) period. RESULTS: Sixty-two percent were cleared with 5 mm margins. A total of 15 mm margins were required to achieve a 97% clearance rate. Difference in clearance rate between margin thresholds was significant (P < .001). Tumor location on the cheek and larger preoperative size correlated with requiring >5 mm margins to achieve tumor clearance (P = .006 and P = .001, respectively). LIMITATIONS: This is a single-center retrospective study which relies on accurate documentation of clinical data. CONCLUSION: This study demonstrates that MIS on the head and neck often requires margins >5 mm margins to achieve tumor clearance. When Mohs micrographic surgery is not possible, excision margins of ≥10 mm are likely necessary for head and neck tumors.

Extrafacial lentigo maligna: A progression model and enhanced diagnostic techniques using dermatoscopy and reflectance confocal microscopy.

Lentigo maligna (LM) is a subtype of lentiginous melanoma confined to the epidermis, which is associated with chronic sun exposure. Its clinical, dermatoscopic, and histopathological diagnosis can be challenging, particularly in the early and advanced stages, requiring appropriate clinicopathological correlation. This article reviews the clinical presentation, diagnosis through noninvasive methods (dermoscopy and confocal microscopy), and provides insights for diagnosis of extrafacial LM through the presentation of four representative clinical cases from different phases of a theoretical-practical progression model. Recognizing these lesions is crucial, as once they invade the dermis, they can behave like any other type of melanoma.

Dermoscopy of Lentiginous Melanomas and Equivocal Benign Pigmented Macules of the Scalp: A Case-Control Multicentric Study.

INTRODUCTION: Although the dermoscopic features of facial lentiginous melanomas (LM), including lentigo maligna and lentigo maligna melanoma, have been extensively studied, the literature about those located on the scalp is scarce. This study aims to describe the dermoscopic features of scalp LM and assess the diagnostic accuracy of dermoscopy to discriminate them from equivocal benign pigmented macules. METHODS: Consecutive cases of scalp LM and histopathology-proven benign but clinically equivocal pigmented macules (actinic keratoses, solar lentigos, seborrhoeic keratoses, and lichen planus-like keratoses) from four referral centres were included. Dermoscopic features were analysed by two blinded experts. The diagnostic performance of a predictive model was assessed. RESULTS: 56 LM and 44 controls were included. Multiple features previously described for facial and extrafacial LM were frequently identified in both groups. Expert's sensitivity to diagnose scalp LM was 76.8% (63.6-87.0) and 78.6% (65.6-88.4), with specificity of 54.5% (38.9-69.6) and 56.8% (41.0-71.7), and fair agreement (kappa coefficient 0.248). The strongest independent predictors of malignancy were (OR, 95% CI) chaos of colour (15.43, 1.48-160.3), pigmented reticular lines (14.96, 1.68-132.9), increased density of vascular network (3.45, 1.09-10.92), and perifollicular grey circles (2.89, 0.96-8.67). The predictive model achieved 85.7% (73.8-93.6) sensitivity, 61.4% (45.5-75.6) specificity, and 81.5 (73.0-90.0) area under curve to discriminate benign and malignant lesions. A diagnostic flowchart was proposed, which should improve the diagnostic performance of dermoscopy. CONCLUSION: Both facial and extrafacial dermoscopic patterns can be identified in scalp LM, with considerable overlap with benign pigmented macules, leading to low specificity and interobserver agreement on dermoscopy.

Characteristics of dermal vascularity in melasma and solar lentigo.

BACKGROUND /PURPOSE: Melasma and solar lentigo (SL) are major benign hyperpigmented lesions, and both have been shown to involve the dermal vasculature. This review discusses current knowledge regarding the clinical characteristics of dermal vascularity in melasma and SL, as well as the results of relevant molecular biological investigations. METHODS: PubMed and Google Scholar were searched in December 2023 to identify articles related to melasma, SL, and the dermal vasculature in these lesions. RESULTS: Vascular morphologies in melasma and SL have been detected by histological and non-invasive methods, including modalities such as optical coherence tomography. Biological studies have indicated that factors secreted from vascular endothelial cells, such as stem cell factor and endothelin-1, can promote melanogenesis. With respect to phototherapy, blood vessel-targeting laser treatments are expected to provide long-term suppression of pigmentation, but this regimen is only effective when dilated capillaries are visible. CONCLUSION: In both melasma and SL, clinical and experimental investigations are revealing the contributions of dermal vascularity to hyperpigmentation. More effective treatment may require identification of hyperpigmentation subtypes. In the future, knowledge of treatment (including phototherapy) is expected to accumulate through reliable and validated non-invasive measurements.

Refractory solar lentigines successfully treated with 532-nm nanosecond Nd:YAG Vasculature Salvage Laser Surgery (VSLS) system: Case series.

BACKGROUND: Solar lentigo, a common epidermal hyperpigmented lesion found in sun-exposed areas, results from the proliferation of melanocytes and the accumulation of melanin. Although various treatments for solar lentigo have been explored, they often lead to complications, including prolonged erythema and post-inflammatory hyperpigmentation (PIH), posing significant concerns. OBJECTIVES AND METHODS: This study evaluated the safety and efficacy of the Vasculature Salvage Laser Surgery (VSLS) system. We treated six Korean patients, each with solar lentigo, in a single session using the 532-nm nanosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) VSLS system, with follow-up periods ranging from 3 to 10 weeks. RESULTS: The treatment led to the complete removal of pigmented lesions in all patients without resulting in PIH, even in cases where previous laser treatments had failed. The only side effect observed was mild erythema, which resolved over the long term in most instances. CONCLUSIONS: The VSLS system emerges as a safe and effective treatment for pigmented lesions, including refractory solar lentigines. Nonetheless, additional studies are required to verify its long-term efficacy.

Correlation between the efficacy of picosecond-domain laser treatment for solar lentigo and the vascularity in the upper dermis using optical coherence tomography angiography in Asian women.

OBJECTIVES: The purpose of this study was to noninvasively confirm the characteristics of the dermal vasculature in patients with solar lentigo (SL) and determine any association with the efficacy of picosecond-domain laser (PSL) treatment. METHODS: Thirteen facial SL lesions in 11 Asian female patients were included in this study and evaluated over 12 weeks. An Nd:YAG laser was used at 532 nm and 750 ps. Skin color and morphological structure were evaluated by ANTERA-3D® and optical coherence tomography (OCT), respectively. To analyze the vascularity in the upper dermis, an OCT angiography (OCTA) algorithm was applied to the OCT data. RESULTS: After PSL treatment, significant improvement in both hyperpigmentation and abnormally thickened epidermis was observed, but the efficacy varied for each lesion. There was a significant correlation between the change in the melanin index due to PSL treatment and preoperative vascular density in the upper dermis. CONCLUSIONS: To the best of our knowledge, this is the first report to demonstrate a correlation between the efficacy of PSL treatment of SL lesions and the vascularity in the upper dermis. Methods to evaluate the vasculature in the upper dermis may be useful for preoperative prediction of the efficacy of PSL treatment for SL lesions.

Multi-System-Level Analysis Reveals Differential Expression of Stress Response-Associated Genes in Inflammatory Solar Lentigo.

Although the pathogenesis of solar lentigo (SL) involves chronic ultraviolet (UV) exposure, cellular senescence, and upregulated melanogenesis, underlying molecular-level mechanisms associated with SL remain unclear. The aim of this study was to investigate the gene regulatory mechanisms intimately linked to inflammation in SL. Skin samples from patients with SL with or without histological inflammatory features were obtained. RNA-seq data from the samples were analyzed via multiple analysis approaches, including exploration of core inflammatory gene alterations, identifying functional pathways at both transcription and protein levels, comparison of inflammatory module (gene clusters) activation levels, and analyzing correlations between modules. These analyses disclosed specific core genes implicated in oxidative stress, especially the upregulation of nuclear factor kappa B in the inflammatory SLs, while genes associated with protective mechanisms, such as SLC6A9, were highly expressed in the non-inflammatory SLs. For inflammatory modules, Extracellular Immunity and Mitochondrial Innate Immunity were exclusively upregulated in the inflammatory SL. Analysis of protein-protein interactions revealed the significance of CXCR3 upregulation in the pathogenesis of inflammatory SL. In conclusion, the upregulation of stress response-associated genes and inflammatory pathways in response to UV-induced oxidative stress implies their involvement in the pathogenesis of inflammatory SL.

Wood's light in inflammatory and autoimmune dermatoses, infections and skin cancer. / Luz de Wood en dermatosis inflamatorias, autoinmunes, infecciones y cáncer cutáneo.

Wood's lamp (WL) is a useful, cost-effective, and easy-to-learn diagnostic tool. Despite its advantages, the use of WL among dermatologists is limited. In porokeratosis, the "diamond necklace" sign often reported is consistent with the white fluorescence of the hyperkeratotic scale. Subclinical morphea lesions are seen as well-defined dark macules. Among pigmentary disorders, the bluish fluorescence of vitiligo, increased contrast of epidermal melasma, and follicular-centered red fluorescence of progressive macular hypomelanosis stand out. Regarding skin infections, erythrasma is associated with a coral red fluorescence; tinea versicolor, with a yellow-green fluorescence; Pseudomonas aeuriginosa, with a green fluorescence; and scabies with a blue-white fluorescence in the acarine grooves. In skin cancer, WL has been used to outline the surgical margins of lentigo maligna and non-melanoma skin cancer, with variable results.

Dermoscopy of atypical pigmented lesions of the face: Variation according to facial areas.

Atypical pigmented facial lesions (aPFLs)-including lentigo maligna (LM) and lentigo maligna melanoma (LMM), solar lentigo (SL), pigmented actinic keratosis (PAK), atypical nevi (AN), seborrheic keratosis (SK) and lichen planus-like keratosis (LPLK)-can exhibit clinical and dermoscopic overlapping features. We aimed to investigate if and how 14 dermoscopic features suggestive for the aforementioned aPFLs vary according to six facial sites among 1197 aPFLs cases (excised to rule out malignancy) along with lesion and patients' metadata. According to distribution and association analysis, aPFLs on the forehead of a male patient aged > 69 years displaying the obliterated follicular openings pattern, appear to be more at risk of malignancy. Of converse, aPFLs of the orbital/cheek/nose area with evident and regular follicular openings with diameter < 10 mm in a female aged below 68 are probably benign. The obliterated follicular openings, keratin plugs, evident and regular follicular openings and target-like pattern features differed significantly among six facial areas in all aPFLs cases. Lesion of the nose may show both features suggestive of malignancy and benignity (e.g. many SL and PAK may display target-like pattern and some LM/LMM cases display keratin plugs and evident and follicular openings), making these features less specific.

Histologic margin status is a predictor of relapse in lentigo maligna melanoma.

BACKGROUND: Most surgical margins for lentigo maligna melanomas reported in the literature are clinical and not histologic. OBJECTIVES: We sought to determine whether histologic margin status is an independent predictor of progression. METHODS: Clinicopathologic information of 268 invasive lentigo maligna melanomas diagnosed from 1990-2019 were analyzed. Statistical analyses were performed using Cox proportional hazards model and Boruta method. RESULTS: A total of 75% of the lesions were located on the head and neck. The range of follow-up for all patients was 0 to 31.8 years (median, 10.2 years). Time to local recurrence ranges from 0 to 20 years (median, 3 years). Progression developed in 54 (20.1%) of 268 patients. Local recurrence was seen only in 36 (13.4%), both local recurrence and subsequent metastasis in 7 (2.6%), and only metastasis in 11 (4.1%) of 268 patients. Histologic margin status (positive and close/<3 mm) and tumor site (head and neck location) significantly correlated with worse progression-free survival. LIMITATIONS: Single institution and retrospective study. CONCLUSIONS: Histologic margin status is the strongest predictor of progression for lentigo maligna melanoma. Patients with positive or close/<3 mm histologic margins should consider a re-excision due to the increased risk of relapse.

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

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

Understanding melanoma in situ: Lentigo maligna surgical treatment terminology and guideline adherence, a targeted review.

BACKGROUND: Malignant melanoma in-situ, lentigo maligna (MMIS-LM) can be successfully treated with several different surgical techniques; however, the literature is inconsistent in defining them. OBJECTIVE: To comprehensively define and describe the national guideline recommended surgical techniques used to treat MMIS-LM to help clarify and standardize this terminology to ensure compliance with the guidelines. METHODS: A targeted literature review was performed from 1990 to 2022 focusing on articles that discussed the national guideline recommended surgical techniques of wide local excision, Mohs micrographic surgery (MMS), modified Mohs surgery, and staged excision/Slow-Mohs for MMIS-LM, as well as the related methods of tissue processing. National Comprehensive Cancer Network and American Academy of Dermatology guidelines were reviewed to identify how the techniques need to be employed to be compliant with guideline recommendations. RESULTS: We describe the various surgical and tissue processing techniques and discuss advantages and disadvantages of each. LIMITATIONS: This paper was styled as a narrative review defining and clarifying terminology and technique and does not investigate these topics more broadly. CONCLUSION: Understanding the methodology and terminology for these surgical procedures and tissue processing methods is critical so that both general dermatologists and surgeons can employ these techniques effectively for optimal patient care.

Disorders of hyperpigmentation. Part I. Pathogenesis and clinical features of common pigmentary disorders.

Disorders of hyperpigmentation are common and, depending on the extent and location of involvement, can affect the quality of life and pose a significant psychologic burden for patients. Given the similarities in presentation of the various causes of hyperpigmentation, it is often difficult to elucidate the etiology of these conditions, which is important to guide management. Furthermore, certain disorders, such as lichen planus pigmentosus and ashy dermatosis, have similar clinical and/or histologic presentations, and their classification as distinct entities has been debated upon, leading to additional confusion. In this review, the authors selected commonly encountered disorders of hyperpigmentation of the skin, subdivided into epidermal, dermal, or mixed epidermal-dermal disorders based on the location of pigment deposition, along with disorders of hyperpigmentation of the mucosa and nails. Melanocytic nevi, genetic disorders, and systemic causes of hyperpigmentation were largely excluded and considered to be outside the scope of this review. We discussed the pathogenesis of hyperpigmentation as well as the clinical and histologic features of these conditions, along with challenges encountered in their diagnosis and classification. The second article in this 2-part continuing medical education series focuses on the medical and procedural treatments of hyperpigmentation.

Line-field confocal optical coherence tomography of lentigo maligna with horizontal and vertical histopathologic correlations.

Lentigo maligna (LM) is a subtype of in situ melanoma that classically presents in elderly patients as a slowly growing lesion on sun-exposed areas that may evolve to invasive melanoma. Line-field confocal optical coherence tomography (LC-OCT) is a new non-invasive technique for a real-time, vertical, and horizontal skin imaging with high resolution close to conventional histopathology. We present the LC-OCT features of an LM of the nose in a 49-year-old white man along with their horizontal and vertical histopathological correlations. LC-OCT was able to detect in vivo, in both horizontal and vertical imaging, the main microscopic features typical of LM by showing, in the epidermis and around the hair follicles, the presence of large, bright roundish, or dendritic atypical cells, with evident nuclei, corresponding to atypical melanocytes with a tendency toward folliculotropism. A strong correspondence between LC-OCT images and vertical and horizontal histopathological sections was observed. Our study, although limited to a single case, is indicative of the great potential of LC-OCT to improve the non-invasive diagnosis of LM.

Can we predict postinflammatory hyperpigmentation after laser treatment based on dermoscopic findings of solar lentigo?

Solar lentigo (SL) commonly occurs as hyperpigmented macules in areas exposed to ultraviolet radiation. It typically shows an increased number of melanocytes in the basal cell layer of the skin, with or without elongated rete ridges. This retrospective study aimed to evaluate the characteristic dermoscopic patterns, reflecting different histopathological features, which might be valuable in predicting the possibility of postinflammatory hyperpigmentation (PIH) occurring after laser treatment. In total, 88 Korean patients diagnosed with biopsy-proven SL (a total of 90 lesions were diagnosed) between January, 2016 and December, 2021 were included. Histopathological patterns were classified into six categories. Dermoscopic features were classified into six categories. Pseudonetwork pattern and rete ridge elongation showed a statistically significant negative correlation. This means that a flatter epidermis is likely to manifest as a pseudonetwork pattern. The erythema pattern showed a significant positive correlation with interface changes and inflammatory infiltration. Bluish-gray granules (peppering), a characteristic dermoscopic finding, showed significant positive correlations with interface changes, inflammatory infiltration, and dermal melanophages. Clinicians considering laser treatment for patients with SL should perform dermoscopic tests before treatment. The pseudonetwork relates to flattened epidermis and fewer Langerhans cells; thus, a lower remission of PIH after laser treatment might be expected. If bluish-gray granules or erythema are observed, inflammatory conditions are likely to be involved. In such cases, regression of the inflammatory response through drug therapy, such as topical corticosteroids, should be a priority option before laser treatment.