Diagnose und Therapie aktinischer Keratosen: Diagnosis and therapy of actinic keratosis.

Actinic keratosis (AK) is considered a chronic and recurring in situ skin neoplasia, with a possible transformation into invasive squamous cell carcinoma (SCC). Among others, predominant risk factors for development of AK are UV-light exposure and immunosuppression. Basal epidermal keratinocyte atypia (AK I) and proliferation (PRO Score) seem to drive malignant turnover, rather than clinical appearance of AK (Olsen I-III). Due to the invasiveness of punch biopsy, those histological criteria are not regularly assessed. Non-invasive imaging techniques, such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM) and line-field confocal OCT (LC-OCT) are helpful to distinguish complex cases of AK, Bowen's disease and SCC. Moreover, LC-OCT can visualize the epidermis and the papillary dermis at cellular resolution, allowing real-time PRO Score assessment. The decision-making for implementation of therapy is still based on clinical risk factors, ranging from lesion- to field-targeted and ablative to non-ablative regimes, but in approximately 85% of the cases a recurrence of AK can be observed after a 1-year follow-up. The possible beneficial use of imaging techniques for a non-invasive follow-up of AK to detect recurrence or invasive progression early on should be subject to critical evaluation in further studies.

Diagnosis and therapy of actinic keratosis.

Actinic keratosis (AK) is considered a chronic and recurring in situ skin neoplasia, with a possible transformation into invasive squamous cell carcinoma (SCC). Among others, predominant risk factors for development of AK are UV-light exposure and immunosuppression. Basal epidermal keratinocyte atypia (AK I) and proliferation (PRO score) seem to drive malignant transformation, rather than clinical appearance of AK (Olsen I-III). Due to the invasiveness of punch biopsy, those histological criteria are not regularly assessed. Non-invasive imaging techniques, such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM) and line-field confocal OCT (LC-OCT) are helpful to distinguish complex cases of AK, Bowen's disease, and SCC. Moreover, LC-OCT can visualize the epidermis and the papillary dermis at cellular resolution, allowing real-time PRO score assessment. The decision-making for implementation of therapy is still based on clinical risk factors, ranging from lesion- to field-targeted and ablative to non-ablative regimens, but in approximately 85% of the cases a recurrence of AK can be observed after a 1-year follow-up. The possible beneficial use of imaging techniques for a non-invasive follow-up of AK to detect recurrence or invasive progression early on should be subject to critical evaluation in further studies.

Dynamic Optical Coherence Tomography of Blood Vessels in Cutaneous Melanoma-Correlation with Histology, Immunohistochemistry and Dermoscopy.

Dermoscopy adds important information to the assessment of cutaneous melanoma, but the risk of progression is predicted by histologic parameters and therefore requires surgery and histopathologic preparation. Neo-vascularization is crucial for tumor progression and worsens prognosis. The aim of this study was the in vivo evaluation of blood vessel patterns in melanoma with dynamic optical coherence tomography (D-OCT) and the correlation with dermoscopic and histologic malignancy parameters for the risk assessment of melanoma. In D-OCT vessel patterns, shape, distribution and presence/type of branching of 49 melanomas were evaluated in vivo at three depths and correlated with the same patterns in dermoscopy and with histologic parameters after excision. In D-OCT, blood vessel density and atypical shapes (coils and serpiginous vessels) increased with higher tumor stage. The histologic parameters ulceration and Hmb45- and Ki67-positivity increased, whereas regression, inflammation and PD-L1-positivity decreased with risk. CD31, VEGF and Podoplanin correlated with D-OCT vasculature findings. B-RAF mutation status had no influence. Due to pigment overlay and the summation effect, the vessel evaluation in dermoscopy and D-OCT did not correlate well. In summary, atypical vessel patterns in melanoma correlate with histologic parameters for risk for metastases. Tumor vasculature can be noninvasively assessed using D-OCT before surgery.

Innovation in Actinic Keratosis Assessment: Artificial Intelligence-Based Approach to LC-OCT PRO Score Evaluation.

Actinic keratosis (AK) is a common skin cancer in situ that can progress to invasive SCC. Line-field confocal optical coherence tomography (LC-OCT) has emerged as a non-invasive imaging technique that can aid in diagnosis. Recently, machine-learning algorithms have been developed that can automatically assess the PRO score of AKs based on the dermo-epidermal junction's (DEJ's) protrusion on LC-OCT images. A dataset of 19.898 LC-OCT images from 80 histologically confirmed AK lesions was used to test the performance of a previous validated artificial intelligence (AI)-based LC-OCT assessment algorithm. AI-based PRO score assessment was compared to the imaging experts' visual score. Additionally, undulation of the DEJ, the number of protrusions detected within the image, and the maximum depth of the protrusions were computed. Our results show that AI-automated PRO grading is highly comparable to the visual score, with an agreement of 71.3% for the lesions evaluated. Furthermore, this AI-based assessment was significantly faster than the regular visual PRO score assessment. The results confirm our previous findings of the pilot study in a larger cohort that the AI-based grading of LC-OCT images is a reliable and fast tool to optimize the efficiency of visual PRO score grading. This technology has the potential to improve the accuracy and speed of AK diagnosis and may lead to better clinical outcomes for patients.

Artificial intelligence-based PRO score assessment in actinic keratoses from LC-OCT imaging using Convolutional Neural Networks.

BACKGROUND AND OBJECTIVES: The histological PRO score (I-III) helps to assess the malignant potential of actinic keratoses (AK) by grading the dermal-epidermal junction (DEJ) undulation. Line-field confocal optical coherence tomography (LC-OCT) provides non-invasive real-time PRO score quantification. From LC-OCT imaging data, training of an artificial intelligence (AI), using Convolutional Neural Networks (CNNs) for automated PRO score quantification of AK in vivo may be achieved. PATIENTS AND METHODS: CNNs were trained to segment LC-OCT images of healthy skin and AK. PRO score models were developed in accordance with the histopathological gold standard and trained on a subset of 237 LC-OCT AK images and tested on 76 images, comparing AI-computed PRO score to the imaging experts' visual consensus. RESULTS: Significant agreement was found in 57/76 (75%) cases. AI-automated grading correlated best with the visual score for PRO II (84.8%) vs. PRO III (69.2%) vs. PRO I (66.6%). Misinterpretation occurred in 25% of the cases mostly due to shadowing of the DEJ and disruptive features such as hair follicles. CONCLUSIONS: The findings suggest that CNNs are helpful for automated PRO score quantification in LC-OCT images. This may provide the clinician with a feasible tool for PRO score assessment in the follow-up of AK.

Line-field confocal optical coherence tomography in melanocytic and non-melanocytic skin tumors.

INTRODUCTION: Line-field confocal optical coherence tomography (LC-OCT) is a recently introduced, non-invasive skin imaging technique combining the technical advantages of reflectance confocal microscopy and conventional OCT in terms of isotropic resolution and in-tissue penetration. Several studies have been published so far about the use of LC-OCT in melanocytic and non-melanocytic skin tumors. The aim of this review was to summarize the currently available data on the use of LC-OCT for benign and malignant melanocytic and non-melanocytic skin tumors. EVIDENCE ACQUISITION: We searched scientific databases for any literature published up to 30th April 2023 and concerning the use of LC-OCT for melanocytic and non-melanocytic skin tumors. Identified papers were evaluated, and relevant information was extracted. EVIDENCE SYNTHESIS: A total of 29 studies were found including original articles, short reports, and letters to the Editor: 6 applied to melanocytic skin tumors, 22 to non-melanocytic skin tumors and 1 to both. The use of LC-OCT increased the diagnostic accuracy for melanocytic and non-melanocytic skin lesions. The highest diagnostic performance was found for basal cell carcinoma (BCC), but significant improvements in the diagnostic accuracy were also detected for the differentiation of actinic keratosis (AK) from squamous cell carcinoma (SCC) and of melanoma from nevi. The LC-OCT features of other skin tumors were also described and successfully correlated with histopathology. CONCLUSIONS: LC-OCT proved to increase the diagnostic accuracy for melanocytic and non-melanocytic skin lesions, thanks to the combination of high resolution/penetration, 3D reconstructions, and integrated dermoscopy. Although BCC seems the most suitable tumors for LC-OCT examination, the device is extremely performant for the differentiation of AK from SCC and the discrimination of melanoma from nevi as well. Additional studies on diagnostic performance and new investigations about the presurgical assessment of tumor margins with LC-OCT and its association with human and artificial intelligence algorithms are in progress.

How efficient is laser therapy for telangiectasias, spider veins, and cherry angiomas?-A study using dynamic optical coherence tomography.

OBJECTIVES: A clinical study to investigate the effectiveness of pulsed dye laser (PDL) versus Nd:YAG laser in the treatment of telangiectasias, spider veins and cherry angiomas. Dynamic optical coherence tomography (D-OCT) was introduced as an innovative follow-up tool for evaluation of blood flow within superficial vessels and to allow visualization of morphological changes of the vasculature in vivo. The final aim of this study was to demonstrate a possible treatment benefit comparing both laser types. MATERIALS AND METHODS: Vessel structures of 102 skin lesions were documented photographically and dermoscopically. Subsequently, lesions were imaged using optical coherence tomography before laser therapy (a), directly after the treatment (p) and after a follow-up 4-6 weeks after laser treatment. All lesions were treated using either a 595 nm PDL or a 1064 nm Nd:YAG laser. Two main vessel parameters, namely density and diameter, and their possible changes during follow-up were observed in 150/300/500 µm penetration depth using D-OCT and were subsequently compared between both treatment groups. Other analyzed vessel parameters were depth of the plexus, mean diameter, mean density, top edge of the vessel, columns, and spikes. RESULTS: Both laser types are suitable options for the treatment of vascular skin lesions, with the most significant effect on cherry angiomas. PDL shows better results treating smaller vessels in upper skin regions, in comparison to Nd:YAG laser, achieving better results on deeper vessels, like spider veins. Using the applied laser settings, there was no statistically significant effect on telangiectasias. CONCLUSION: D-OCT represents a new, noninvasive imaging method to evaluate blood flow and vessel morphology in the follow-up of telangiectasias, spider veins, and cherry angiomas, which underwent laser therapy.

Implementation of a dermatoscopy curriculum during residency at Augsburg University Hospital in Germany.

BACKGROUND AND OBJECTIVES: To date, there is no structured program for dermatoscopy training during residency in Germany. Whether and how much dermatoscopy training is acquired is left to the initiative of each resident, although dermatoscopy is one of the core competencies of dermatological training and daily practice. The aim of the study was to establish a structured dermatoscopy curriculum during residency at the University Hospital Augsburg. PATIENTS AND METHODS: An online platform with dermatoscopy modules was created, accessible regardless of time and place. Practical skills were acquired under the personal guidance of a dermatoscopy expert. Participants were tested on their level of knowledge before and after completing the modules. Test scores on management decisions and correct dermatoscopic diagnosis were analyzed. RESULTS: Results of 28 participants showed improvements in management decisions from pre- to posttest (74.0% vs. 89.4%) and in dermatoscopic accuracy (65.0% vs. 85.6%). Pre- vs. posttest differences in test score (7.05/10 vs. 8.94/10 points) and correct diagnosis were significant (p < 0.001). CONCLUSIONS: The dermatoscopy curriculum increases the number of correct management decisions and dermatoscopy diagnoses. This will result in more skin cancers being detected, and fewer benign lesions being excised. The curriculum can be offered to other dermatology training centers and medical professionals.

Optical coherence tomography-guided Nd:YAG laser treatment and follow-up of basal cell carcinoma.

OBJECTIVES: Basal cell carcinoma (BCC) is the most common skin tumor with an annually increasing incidence. Standard care requires several visits for diagnosis and treatment. Optical coherence tomography (OCT) as a diagnostic tool increases the sensitivity (95%) and specificity (77%) of the diagnosis of BCC. Although laser therapy is not the standard of care, the long-pulsed 1064 nm Nd:YAG laser seems to be a promising option. However, data are scarce. The published papers had a short follow-up (FU) time and used to some extent inferior methods to detect complete tumor clearance. To address this research gap, this study evaluates the efficiency of laser treatment by FU OCT. We pursue a patient-focused approach and combine OCT with Nd:YAG laser treatment in one procedure. MATERIALS AND METHODS: The study was conducted as a prospective, single-center trial that recruited biopsy-confirmed or OCT-proven BCC with a tumor thickness of less than 1.2 mm. Patients underwent two or three repeated sessions with the Nd:YAG laser (5-6 mm spot, fluence of 120-140 J/cm2 , pulse duration of 8-10 milliseconds). Each BCC was assessed at baseline, and 3 and 12 months after laser treatment by clinical image, dermoscopy, and OCT. Incomplete tumor clearance (ITC) was defined as a clearly detectable BCC on the OCT image or a biopsy-confirmed BCC in the treated area. RESULTS: Forty-five patients completed the 12-month FU (46.7% women; median age of 74.0 [52-88] years) with a total number of 78 BCC lesions. At baseline, all patients had their BCC diagnosed by OCT (tumor thickness of 0.6 [0.4; 0.8] mm), 15.4% lesions were additionally diagnosed by histopathology. The most common subtype of BCC was superficial (48.7%), followed by nodular (47.4%) and infiltrative (3.8%). ITC rate after the treatment using Nd:YAG laser was 30.8% (95% CI: 20.8%-42.2%) (24/78) after 3 months and 7.4% (95% CI: 2.1%-17.9%) (4/54) after 12 months. ITC was not associated with histological subtype, tumor thickness, or location. If ITC was detected, the lesion was treated again. Out of 19 lesions with at least one additional laser treatment, 7 lesions (36.8%) suffered from incomplete tumor removal. In 46.7% of the treated lesions, the cosmetic outcome was rated as moderate or severe scarring after 12 months. CONCLUSION: Our results demonstrate that the ITC rate of BCC treated with the Nd:YAG laser is much higher (up to one-third) than reported, although the laser settings were identical to prior studies. This is especially evident at the 3-month FU. In addition, we witnessed a larger number of side effects and a worse cosmetic outcome compared to previous studies.

Line-Field Confocal Optical Coherence Tomography: A New Tool for the Differentiation between Nevi and Melanomas?

Until now, the clinical differentiation between a nevus and a melanoma is still challenging in some cases. Line-field confocal optical coherence tomography (LC-OCT) is a new tool with the aim to change that. The aim of the study was to evaluate LC-OCT for the discrimination between nevi and melanomas. A total of 84 melanocytic lesions were examined with LC-OCT and 36 were also imaged with RCM. The observers recorded the diagnoses, and the presence or absence of the 18 most common imaging parameters for melanocytic lesions, nevi, and melanomas in the LC-OCT images. Their confidence in diagnosis and the image quality of LC-OCT and RCM were evaluated. The most useful criteria, the sensitivity and specificity of LC-OCT vs. RCM vs. histology, to differentiate a (dysplastic) nevus from a melanoma were analyzed. Good image quality correlated with better diagnostic performance (Spearman correlation: 0.4). LC-OCT had a 93% sensitivity and 100% specificity compared to RCM (93% sensitivity, 95% specificity) for diagnosing a melanoma (vs. all types of nevi). No difference in performance between RCM and LC-OCT was observed (McNemar's p value = 1). Both devices falsely diagnosed dysplastic nevi as non-dysplastic (43% sensitivity for dysplastic nevus diagnosis). The most significant criteria for diagnosing a melanoma with LC-OCT were irregular honeycombed patterns (92% occurrence rate; 31.7 odds ratio (OR)), the presence of pagetoid spread (89% occurrence rate; 23.6 OR) and the absence of dermal nests (23% occurrence rate, 0.02 OR). In conclusion LC-OCT is useful for the discrimination between melanomas and nevi.

Line-Field Confocal Optical Coherence Tomography Increases the Diagnostic Accuracy and Confidence for Basal Cell Carcinoma in Equivocal Lesions: A Prospective Study.

Diagnosing clinically unclear basal cell carcinomas (BCCs) can be challenging. Line-field confocal optical coherence tomography (LC-OCT) is able to display morphological features of BCC subtypes with good histological correlation. The aim of this study was to investigate the accuracy of LC-OCT in diagnosing clinically unsure cases of BCC compared to dermoscopy alone and in distinguishing between superficial BCCs and other BCC subtypes. Moreover, we addressed pitfalls in false positive cases. We prospectively enrolled 182 lesions of 154 patients, referred to our department to confirm or to rule out the diagnosis of BCC. Dermoscopy and LC-OCT images were evaluated by two experts independently. Image quality, LC-OCT patterns and criteria, diagnosis, BCC subtype, and diagnostic confidence were assessed. Sensitivity and specificity of additional LC-OCT were compared to dermoscopy alone for identifying BCC in clinically unclear lesions. In addition, key LC-OCT features to distinguish between BCCs and non-BCCs and to differentiate superficial BCCs from other BCC subtypes were determined by linear regressions. Diagnostic confidence was rated as "high" in only 48% of the lesions with dermoscopy alone compared to 70% with LC-OCT. LC-OCT showed a high sensitivity (98%) and specificity (80%) compared to histology, and these were even higher (100% sensitivity and 97% specificity) in the subgroup of lesions with high diagnostic confidence. Interobserver agreement was nearly perfect (95%). The combination of dermoscopy and LC-OCT reached a sensitivity of 100% and specificity of 81.2% in all cases and increased to sensitivity of 100% and specificity of 94.9% in cases with a high diagnostic confidence. The performance of LC-OCT was influenced by the image quality but not by the anatomical location of the lesion. The most specific morphological LC-OCT criteria in BCCs compared to non-BCCs were: less defined dermoepidermal junction (DEJ), hyporeflective tumor lobules, and dark rim. The most relevant features of the subgroup of superficial BCCs (sBCCs) were: string of pearls pattern and absence of epidermal thinning. Our diagnostic confidence, sensitivity, and specificity in detecting BCCs in the context of clinically equivocal lesions significantly improved using LC-OCT in comparison to dermoscopy only. Operator training for image acquisition is fundamental to achieve the best results. Not only the differential diagnosis of BCC, but also BCC subtyping can be performed at bedside with LC-OCT.

[Optical coherence tomography for the differential diagnosis of unclear nail pigmentation]. / Optische Kohärenztomographie zur differenzialdiagnostischen Abklärung unklarer Nagelpigmentierungen.

In daily practice, nail pigmentation can be a diagnostic challenge, especially if the dermoscopic findings are nonspecific. We present examples of cases, in which optical coherence tomography-a rapid, noninvasive imaging method-showed typical changes that were indicative for the diagnosis.

Dynamic Optical Coherence Tomography: A Non-Invasive Imaging Tool for the Distinction of Nevi and Melanomas.

Along with the rising melanoma incidence in recent decades and bad prognoses resulting from late diagnoses, distinguishing between benign and malignant melanocytic lesions has become essential. Unclear cases may require the aid of non-invasive imaging to reduce unnecessary biopsies. This multicentric, case-control study evaluated the potential of dynamic optical coherence tomography (D-OCT) to identify distinguishing microvascular features in nevi. A total of 167 nevi, including dysplastic ones, on 130 participants of all ages and sexes were examined by D-OCT and dermoscopy with a histological reference. Three blinded analyzers evaluated the lesions. Then, we compared the features to those in 159 melanomas of a prior D-OCT study and determined if a differential diagnosis was possible. We identified specific microvascular features in nevi and a differential diagnosis of melanomas and nevi was achieved with excellent predictive values. We conclude that D-OCT overcomes OCT´s inability to distinguish melanocytic lesions based on its focus on microvascularization. To determine if an addition to the gold standard of a clinical-dermoscopic examination improves the diagnosis of unclear lesions, further studies, including a larger sample of dysplastic nevi and artificial intelligence, should be conducted.

Rastreio radiológico para tuberculose em uma penitenciária do sul do Brasil / Radiological screening for tuberculosis in a prison in the south of Brazil

Introdução: Conhecer o perfil da população privada de liberdade da Penitenciária Modulada de Osório (PMO), do ponto de vista radiológico e estimar a prevalência da tuberculose ativa no presídio.Métodos: Foi realizada análise retrospectiva de 677 radiografias de tórax obtidas para rastreio de tuberculose e de dados da ficha de atendimento do setor de Radiologia no período de julho a outubro de 2019.Resultados: Foram detectadas 150 radiografias alteradas, o que representa 22% dos 677 exames. Dos 150 exames alterados, 109 (16% do total e 72% dos alterados) apresentavam lesões com características de doença granulomatosa. Dos 677 pacientes, 11,5% referiram tratamento atual ou prévio para tuberculose e estes representam 38% dos casos com radiografias alteradas. Foram detectados 50 pacientes sem história prévia de tuberculose com lesões de aspecto muito provavelmente devido a tuberculose com características de doença ativa (7,3% do total), os quais foram encaminhados para investigação como casos novos. Em relação ao questionário aplicado, não foi observada diferença significativa entre os pacientes que referiam ou negavam tosse entre os com exames normais e alterados.Conclusões: Os indivíduos privados de liberdade apresentaram alta prevalência de alterações radiológicas com aspecto sugestivo de doença granulomatosa. Estes achados permitem inferir que na Penitenciária Modulada de Osório há elevada prevalência de tuberculose, provavelmente em níveis semelhantes a outras casas prisionais do Brasil.

Introduction: To determine the radiologic profile of 'the prisoners at Osório Modular Prison and estimate the prevalence of active tuberculosis in the institution.Methods: We retrospectively analyzed 677 chest radiographs obtained for tuberculosis screening and data from the medical records of prisoners seen at the Radiology Department from July to October 2019.Results: Of 677 radiographs, 150 (22%) showed abnormalities. Of these, 109 (16% of total or 72% of abnormal radiographs) showed lesions characteristic of granulomatous disease. Of all 677 patients, 11.5% reported current or previous treatment of tuberculosis, accounting for 38% of all abnormal radiographs. Fifty patients with no previous history of tuberculosis had lesions that were most likely due to active tuberculosis (7.3% of total), and were referred for further investigation as new cases. The responses to the questionnaire revealed no significant difference between patients who reported or denied coughing when comparing those with normal vs abnormal radiographs.Conclusions: Individuals deprived of liberty had a high prevalence of radiologic abnormalities suggestive of granulomatous disease. These findings allow us to infer that there is a high prevalence of tuberculosis at Osório Modular Prison, probably at levels comparable to those of other prison facilities in Brazil.

[Confocal line-field OCT]. / Konfokale Line-Field-OCT.

Optical coherence tomography (OCT) and confocal laser microscopy (CLSM) are established non-invasive methods in clinical dermatological routine diagnosis. Whereas CLSM is especially useful to distinguish between nevi and melanoma, OCT is suitable for the diagnosis and differentiation of non-melanoma skin cancer. Line-field confocal optical coherence tomography (LC-OCT) is a new innovative device, which has better cellular resolution than OCT and a higher penetration depth than CLSM. Similar to CLSM, LC-OCT also allows 3D images in real time to be taken. Therefore LC-OCT is very useful for the examination of skin lesions of all kinds, since it unites the features of CLSM and OCT.

[Advances in optical coherence tomography]. / Neues von der optischen Kohärenztomographie.

Optical coherence tomography (OCT) has been able to establish itself in recent years not only in academic-scientific, but also in everyday dermatological practice. Its focus lies on epithelial tumors of the skin, which can be diagnosed intuitively and within a few seconds. Thus, basal cell carcinomas, actinic keratoses, and different stages of field cancerization can be diagnosed and monitored for response to therapy or possible recurrence. This often helps to avoid invasive sample extraction. Recently, the field of OCT and its latest advancement, dynamic OCT (D-OCT), has been expanded to include non-oncologic dermatological diseases. This encompasses inflammatory dermatoses and the analysis of physiological skin parameters such as hydration. Thanks to automated vascular imaging and the measurement of objective parameters such as epidermal thickness, blood flow at depth, optical attenuation coefficient, and skin roughness, more and more characteristics of the skin can be studied in a noninvasive and standardized way. New potential areas of application are eczema, contact allergic dermatitis, psoriasis, rosacea, telangiectasia, acute and chronic wounds, melasma and nevus flammeus but also melanocytic lesions.

In-Vivo LC-OCT Evaluation of the Downward Proliferation Pattern of Keratinocytes in Actinic Keratosis in Comparison with Histology: First Impressions from a Pilot Study.

It is known that actinic keratoses (AKs) can progress to invasive squamous cell carcinoma (SCC). The histological PRO grading of AKs is based on the growth pattern of basal keratinocytes and relates to their progression risk. AKs can be non-invasively characterized by line-field confocal optical coherence tomography (LC-OCT). The aim of the study was to define criteria for an LC-OCT grading of AKs based on the PRO classification and to correlate it with its histological counterpart. To evaluate the interobserver agreement for the LC-OCT PRO classification, fifty AKs were imaged by LC-OCT and biopsied for histopathology. PRO histological grading was assessed by an expert consensus, while two evaluator groups separately performed LC-OCT grading on vertical sections. The agreement between LC-OCT and histological PRO grading was 75% for all lesions (weighted kappa 0.66, 95% CI 0.48-0.83, p ≤ 0.001) and 85.4% when comparing the subgroups PRO I vs. PRO II/III (weighted kappa 0.64, 95% CI 0.40-0.88, p ≤ 0.001). The interobserver agreement for LC-OCT was 90% (Cohen's kappa 0.84, 95% CI 0.71-0.91, p ≤ 0.001). In this pilot study, we demonstrated that LC-OCT is potentially able to classify AKs based on the basal growth pattern of keratinocytes, in-vivo reproducing the PRO classification, with strong interobserver agreement and a good correlation with histopathology.