Basic studies toward ultrafast soft x-ray photoelectron diffraction; its application to probing local structure in iodobenzene molecules.

Ultrafast x-ray photoelectron diffraction (UXPD) for free molecules has a promising potential to probe the local structures of the molecules in an element-specific fashion. Our UXPD scheme consists of three steps: (1) near-infrared laser (NIR) with ns pulse duration aligns sample molecules, (2) ultra-violet laser with fs pulse duration pumps the aligned molecules, and (3) soft x-ray free-electron laser (SXFEL) with fs pulse duration probes the molecules by measuring x-ray photoelectron diffraction (XPD) profiles. Employing steps of (1) and (3), we have measured I 3d XPD profiles from ground state iodobenzene aligned by the NIR laser with the SXFEL. Then, we have intensively calculated I 3d XPD profiles with density functional theory, taking degrees of alignments of the molecules into account, to extract a distance between C and I atoms in iodobenzene from the experimental I 3d XPD profiles. Although we have failed to determine the distance from the comparison between the experimental and theoretical results, we have succeeded in concluding that the degeneracies of the initial state eliminate the sensitivity on molecular structure in the I 3d XPD profiles. Thus, the observation of fine structures in the XPD profiles could be expected, if a nondegenerate molecular orbital is selected for a probe of UXPD. Finally, we have summarized our criteria to perform UXPD successfully: (1) to use SXFEL, (2) to prepare sample molecules with the degree of alignment higher than 0.8, and (3) to select a photoemission process from a nondegenerate inner-shell orbital of sample molecules.

Diagnosis and treatment of nail melanoma: a review of the clinicopathologic, dermoscopic, and genetic characteristics.

Nail melanoma (NM) is an important differential diagnosis in patients with longitudinal melanonychia. However, diagnosis is often challenging as it is difficult to differentiate from other pigmented nail disorders. The main challenge for diagnosis is obtaining adequate nail matrix biopsy specimens for histopathological assessment. Furthermore, the histopathological changes in the early stages of NM are subtle and contribute to a delay in diagnosis and care. Therefore, the integration of clinical and histopathological analyses is essential. Clinical and dermoscopic features, such as a broadened width of asymmetric bands in an irregular pattern, with multicolour pigmentation, periungual pigmentation, and continuous growth, are features that support the diagnosis of NM. The essential histological features that must be assessed are cellular morphology, architectural features, melanocyte density, and inflammatory changes. The reported mutations in NMs were BRAF (0-43%), NRAS (0-31%), KIT (0-50%), NF1 (0-50%), and GNAQ (0-25%). Surgery is the primary treatment for NM. The recommended treatment for in situ or minimally invasive NM is functional surgery, but cases with suspected bone invasion should be treated with amputation. Targeted therapy and immunotherapy are indicated for advanced stages of NM. This review summarizes the updated guidelines for the diagnosis and treatment of NM.

Developing a predictive model for distinguishing invasive nail unit melanoma from nail unit melanoma in situ.

BACKGROUND: Clinical information that distinguishes invasive nail unit melanoma from nail unit melanoma in situ before surgery would aid physicians in the decision-making process and estimating prognosis. However, limited information is available on the detailed demographic and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ for differential diagnosis. OBJECTIVE: This study aimed to investigate the demographic data and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ and establish a predictive model for differentiating these two forms of nail unit melanoma. METHODS: A retrospective observational study of ninety-seven patients diagnosed with nail unit melanoma (59 in situ and 38 invasive cases) in four healthcare centres in South Korea (three tertiary referral hospitals and one second referral hospital) from March 2014 to December 2019. RESULTS: A multivariable analysis revealed that ulcer (odds ratio = 21.6, confidence interval = 2.1-219.8, P = 0.009), total melanonychia (odds ratio = 17.6, confidence interval = 3.0-104.0, P = 0.002), nail plate destruction (odds ratio = 10.9, confidence interval = 2.0-59.4, P = 0.006) and polychromia (odds ratio = 5.3, confidence interval = 1.36-20.57, P = 0.016) were distinctive dermoscopic features of invasive nail unit melanoma. A predictive model with scores ranging from 0 to 6 points demonstrated a reliable diagnostic value (C-statistic = 0.902) in differentiating invasive nail unit melanoma from nail unit melanoma in situ. CONCLUSIONS: Invasive nail unit melanoma and nail unit melanoma in situ have different dermoscopic features. A predictive model based on morphologic dermoscopic features could aid in differentiating invasive nail unit melanoma from nail unit melanoma in situ.

Dermatologist-level classification of malignant lip diseases using a deep convolutional neural network.

BACKGROUND: Deep convolutional neural networks (DCNNs) can classify skin diseases at a level equivalent to a dermatologist, but their performance in specific areas requires further research. OBJECTIVE: To evaluate the performance of a trained DCNN-based algorithm in classifying benign and malignant lip diseases. METHODS: A training set of 1629 images (743 malignant, 886 benign) was used with Inception-Resnet-V2. Performance was evaluated using another set of 344 images and 281 images from other hospitals. Classifications by 44 participants (six board-certified dermatologists, 12 dermatology residents, nine medical doctors not specialized in dermatology and 17 medical students) were used for comparison. RESULTS: The outcomes based on the area under curve, sensitivity and specificity were 0·827 [95% confidence interval (CI) 0·782-0·873], 0·755 (95% CI 0·673-0·827) and 0·803 (95% CI 0·752-0·855), respectively, for the set of 344 images; and 0·774 (95% CI 0·699-0·849), 0·702 (95% CI 0·579-0·808) and 0·759 (95% CI 0·701-0·813), respectively, for the set of 281 images. The DCNN was equivalent to the dermatologists and superior to the nondermatologists in classifying malignancy. After referencing the DCNN result, the mean ± SD Youden index increased significantly for nondermatologists, from 0·201 ± 0·156 to 0·322 ± 0·141 (P < 0·001). CONCLUSIONS: DCNNs can classify lip diseases at a level similar to dermatologists. This will help unskilled physicians discriminate between benign and malignant lip diseases. What's already known about this topic? Deep convolutional neural networks (DCNNs) can classify malignant and benign skin diseases at a level equivalent to dermatologists. The lips are a unique feature in terms of histology and morphology. Previous studies of DCNNs have not investigated tumours on specific locations. What does this study add? This study shows that DCNNs can distinguish rare malignant and benign lip disorders at the same rate as dermatologists. DCNNs can help nondermatologists to distinguish malignant lip diseases. What are the clinical implications of this work? DCNNs can distinguish malignant and benign skin diseases even at specific locations such as the lips, as well as board-certified dermatologists. Malignant lip diseases are rare and difficult for less trained doctors to differentiate them from benign lesions. This study shows that in dermatology, DCNN can help improve decision-making processes for rare skin diseases in specific areas of the body.

Asymptomatic solitary mass on the sacral region.

Nuchal-type fibroma (NTF) is a rare, benign, tumour-like fibrous proliferation of unknown pathogenesis. Despite the name, approximately one-third of cases occur at extranuchal sites. We report a rare case of NTF of the sacral region, an extremely uncommon extranuchal site. As NTF is often misdiagnosed because of its rarity and histopathological similarity with other fibrous tumours, we present this case to increase understanding of this rare disease entity.

The clinical and histopathological characteristics of early-onset basal cell carcinoma in Asians.

BACKGROUND: Basal cell carcinoma (BCC) is by far the most common cancer in white populations. In addition, recent reports have demonstrated an increasing incidence of BCC in Korea. We have observed a significant number of early-onset BCC cases in which the disease occurred in patients younger than 50 years. OBJECTIVE: To investigate the clinicopathological characteristics of early-onset BCC in an Asian population, specifically in Koreans. METHODS: One hundred and five patients with early-onset BCC were enrolled from a total of 1047 BCC patients who underwent surgery between January 1997 and December 2014 (942 patients over the age of 50 years were designated as the control group). RESULTS: Early-onset BCC accounted for 10.03% of all 1047 cases and the incidence over time displayed an incremental trend. The early-onset group displayed similar results as the control group, with a predominance of female BCC patients and the majority of tumours displaying the following characteristics: small in size, occurring in sun-exposed areas and belonging to the noduloulcerative clinical subtype and nodular histopathological subtype. In comparison with a previous study in a Western population, the incidence of the disease in non-exposed areas of the body, as well as the proportion of tumours of the superficial histological subtype, were lower in Asian patients. CONCLUSION: Although the clinicopathological characteristics of BCC are well-known, these characteristics have not been determined for early-onset BCC in an Asian population. Therefore, this study is the first report on early-onset BCC in Asians, specifically in a Korean patient group.

Dermoscopy of subungual haemorrhage: its usefulness in differential diagnosis from nail-unit melanoma.

BACKGROUND: Subungual haemorrhages are characterized by well-circumscribed dots or blotches with a red to red-black pigmentation, but some cases can be difficult to distinguish from subungual melanoma by the naked eye alone. Dermoscopy has proven to be a useful, noninvasive tool in the diagnosis of pigmented lesions in the nail; however, few dermoscopic studies of subungual haemorrhages have been reported. OBJECTIVES: To investigate characteristic dermoscopic patterns of subungual haemorrhages, and to find distinctive features that can differentiate them from nail-unit melanomas. METHODS: Patients with a confirmed diagnosis of either subungual haemorrhage or nail-unit melanoma at a tertiary university hospital were included in the study. Clinical features and dermoscopic patterns were evaluated. RESULTS: Sixty-four patients with a total of 90 lesions of subungual haemorrhage were enrolled in the study. The majority of cases (84%) showed combinations of more than one colour, while 16% had only one colour. The most common colour of the subungual haemorrhages was purple-black, in 37% of cases. A homogeneous pattern was observed in 92% of cases, globular patterns in 42% and streaks in 39%. Peripheral fading and periungual haemorrhages were found in 54% and 22% of cases, respectively. Destruction or dystrophy of the nail plate was observed in 16% of cases. In the 16 cases of nail-unit melanomas, Hutchinson sign, longitudinal irregular bands or lines, triangular shape of bands, vascular pattern, and ulcerations were found in 100%, 81%, 25%, 6% and 81% of cases, respectively. In contrast, these features were not found in subungual haemorrhages. CONCLUSIONS: Dermoscopy provides valuable information for the diagnosis of subungual haemorrhage and aids in the differential diagnosis from nail-unit melanoma.

The use of dermatoscopy to monitor therapeutic response of Bowen disease: a dermatoscopic pathological study.

BACKGROUND: Dermatoscopy is a noninvasive technique that can be helpful in the diagnosis of pigmented and nonpigmented skin tumours. The dermatoscopic evaluation of Bowen disease (BD) improves diagnostic accuracy. OBJECTIVE: To evaluate the usefulness of dermatoscopy as a tool for assessing responses to therapy and recurrence of BD. METHODS: Patients with histopathologically diagnosed BD were prospectively enrolled. In all lesions, 3 months after the end of treatment (photodynamic therapy or 5% imiquimod cream), dermatoscopic and histopathological examinations were repeated to evaluate and correlate changes in dermatoscopic features and histopathological results. Cured lesions were monitored using dermatoscopy during the follow-up period. RESULTS: A total of 23 patients with 29 histopathologically diagnosed BD lesions were included in this study. After treatment, dermatoscopic examination revealed the disappearance of pre-existing vascular structures in 16 lesions, and remaining vascular structures in 13 lesions. Histopathological evaluation of the treated lesions showed remnant intraepithelial neoplasms and increased dermal vascularity in lesions with persistent dermatoscopic vascular structures. However, normal epidermis and decreased dermal vascularity were observed in all but one of the lesions without previous dermatoscopic vascular structures. During the follow-up period, one lesion showed reappearance of previous vascular structures on dermatoscopy 9 months after treatment. Histopathological examination confirmed the recurrence of BD. CONCLUSIONS: Our study demonstrates that the persistence of dermatoscopic vascular structures of BD appears to be associated with residual disease, and disappearance of vascular structures suggests that the disease has been cured. In addition, reappearance of previous dermatoscopic vascular structures indicates the recurrence of BD. Therefore, we suggest that dermatoscopy can be a useful, reliable and noninvasive tool in the therapeutic follow-up of BD.

Dermoscopic features of Bowen's disease in Asians.

BACKGROUND: Previously, dermoscopic features of Bowen's disease (BD) were extensively investigated in two studies, but there were some discrepancies. The dispute necessitated a further study concerning the dermoscopic features of BD. OBJECTIVE: To describe the dermoscopic features of BD in Asians and to assess dermoscopy as a post-treatment monitoring tool of BD. MATERIALS AND METHODS: Dermoscopic examinations of histopathologically diagnosed 26 BD lesions were performed to evaluate for the presence of various dermoscopic features. In addition, the correlating changes of dermoscopic features and histopathological results before and after treatments were assessed in five patients with BD. RESULTS: Dermoscopically, 10 lesions were pigmented and 16 lesions were non-pigmented. The most frequent dermoscopic findings of BD were vascular structures (96%) and a scaly surface (96%). Among vascular structure, glomerular vessels were most frequently observed (77%). The other vascular structures in our study were linear irregular vessels, dotted vessels, polymorphous/atypical vessels and arborizing vessels. Among five patients who had been treated with either photodynamic therapy or 5% imiquimod cream, four patients revealed disappearance of dermoscopic vascular structures, but one patient showed remaining vascular structures after treatment. Skin biopsy from treated lesions disclosed clearance of BD in four patients who had no vascular structures but remaining BD in the patient whose dermoscopic finding displayed no disappearance of vascular structures. CONCLUSIONS: Vascular structures, especially glomerular vessels plus a scaly surface, were common dermoscopic findings of BD in Asians. In addition, existence of dermoscopic vascular structures after treatment appears to be associated with residual disease.

A method for in-vivo analysis for regional arterial wall material property alterations with atherosclerosis: preliminary results.

Atherosclerosis is a diffuse arterial disease developing over many years and resulting in a complicated three-dimensional arterial morphology. The arterial wall material properties have been demonstrated to show regional alterations with atheroma development and growth. We present a mechanical analysis of diseased arterial segments reconstructed from intravascular ultrasound images in order to quantitatively identify regional alterations in the elastic constants with atherosclerotic lesions. We employ a finite element and a displacement sensitivity analysis to divide the arterial segment into regions with different material properties and use an optimization algorithm to identify the elastic constants in these regions. The results with regional variations identified with this method correlated qualitatively with the extent and location of atherosclerotic lesions identified by visual inspection of the affected arteries. The optimized elastic modulus in regions affected by early atherosclerotic lesions ranged from 90.9 to 93.0 kPa where as the corresponding magnitudes in normal arterial segments ranged from 97.9 to 101.0 kPa. This method can be potentially employed to identify the extent and location of atherosclerotic lesions in a systematic analysis and may potentially be used for the early detection of lesion growth.