BACKGROUND: Previous studies have revealed a potential link between inflammatory bowel disease (IBD) and seborrheic keratosis (SK). However, whether this association is causal or confounded remains unknown.
METHODS: We conducted this two-sample Mendelian randomization (TSMR) analysis to clarify bidirectional causality between IBD, including its two primary conditions Crohn\'s disease (CD) and ulcerative colitis (UC), and SK. The summary genetic data of IBD, CD, UC and SK were obtained from accessible genome-wide association studies (GWAS). This TSMR study was primarily performed using inverse-variance weighted (IVW) method, complemented by MR-Egger, weighted median (WM), Bayesian weighted MR (BWMR), MR-robust adjusted profile score (MR-RAPS), MR-pleiotropy residual sum and outlier (MR-PRESSO), and radial IVW MR analyses with modified second-order weights (IVW [Mod 2nd]) methods. Assessment of sensitivity and identification of potential outliers were subsequently conducted to aid interpretation of results.
RESULTS: The forward MR results showed that IBD [odds ratio (OR) = 1.068, 95% confidence interval (CI) = 1.010-1.129, p = 0.020) and its subtype CD (OR = 1.088, 95%CI = 1.038-1.139, p < 0.001) increased the risk of SK. However, the occurrence of SK could not be affected by UC (OR = 1.090, 95%CI = 0.977-1.216, p = 0.123). In the reverse analysis, no causal relationship between SK and IBD (OR = 0.905, 95%CI = 0.813-1.008, p = 0.069), UC (OR = 0.959, 95%CI = 0.860-1.068, p = 0.443), and CD (OR = 0.933, 95%CI = 0.846-1.029, p = 0.165) was identified.
CONCLUSIONS: These findings demonstrate that IBD and its subtype CD could increase the incidence of SK in European populations, whereas SK does not affect IBD occurrence.

We report a case of a 20-year-old young woman with a large stucco keratosis in the mons veneris, one of the clinical variants of Seborrheic keratoses (SKs). Periodic acid-Schiff staining revealed a large number of Malassezia spores in the stratum corneum. After oral antifungal treatment with itraconazole for 4 weeks, the benign tumor was completely cleared without residue or recurrence, which may open a new perspective for exploring the pathogenesis of SKs.

Seborrheic keratosis(SK) is a very common skin tumor which is mostly frequently observed in the trunck, head, neck. SK in the auricle is rare and this condition should be excluded the possibility of malignancy by pathologic diagnosis. We report a case of 66-year-old man who presented with a brownish, papillomatous, verrucous mass in the auricle for the past seven years, which began to growing faster during the previous year. Dermoscopy and histopathological examination were performed and the patient was diagnosed with SK. He was treated with the carbon dioxide(CO2) laser and aminolevulinate photodynamic therapy (ALA-PDT). The CO2 laser was used for the removal of the thick hypertrophic lesions and to enhance the transdermal absorption efficiency of ALA. A 20% ALA cream(118 mg/cm2) was applied to his lesion and sealed for 3 h without light, followed by irradiation with 630-nm LED light (96 J/cm2, 80 mw/cm2). We use fluorescent diagnosis with aminolevulinic acid to define the tumor margins at the first session of ALA-PDT. After 4 sessions of ALA-PDT, the lesion was completely removed and did not recur. Therefore, we consider that ALA-PDT combined with CO2 laser is a safe and effective choice for the treatment of seborrheic keratosis in the auricle.

OBJECTIVE: Lichenoid keratosis (LK, or lichen planus-like keratosis, LPLK) and seborrheic keratosis (SK) present as similar benign keratotic lesions on cosmetically sensitive area, but require different therapies. Both lesions can be easily differentiated based on histological evaluation of biopsy materials. However, the biopsies may cause scarring and result in hyper-pigmentation, which reduces the compliance of the patients to be treated. In this study, we investigated the role of reflectance confocal microscopy (RCM) in the non-invasive differential diagnosis of LK and SK.
METHODS: Cases with facial brown patches or plaques suspicious of SK were enrolled in the study. After written informed consent was obtained, the lesions were photographed, imaged by RCM, and then biopsied. The RCM findings were analyzed and correlated with histology results. Evaluation of the RCM pictures and confirmation with histological results were conducted by two independent dermatologists.
RESULTS: In total, 10 cases were enrolled in the study. The main characteristics of LK lesions observed by RCM were the disarray of the dermal-epidermal junction (DEJ), and marked inflammatory infiltrates in the superficial dermis; while prominent cerebriform pattern, or elongated cords with bulbous projections without significant inflammation reaction, were the features of SK. Among the 10 cases, clinically suspicious of facial SK, 4 were determined as LK, 6 as SK by RCM imaging, and all the RCM findings were confirmed by histological results.
CONCLUSIONS: The RCM features of LK and SK have significant difference, highlighting the important role of RCM in the differential diagnosis of LK and SK, avoiding biopsies and allowing safe treatments.

BACKGROUND: Homocitrulline (Hcit), is involved in the pathological processes of some diseases. However, the role and function of Hcit (CBL) in human skin remains largely obscure.
OBJECTIVE: To investigate the correlation of the level of Hcit in seborrheic keratosis, skin aging, and its clinical significance.
METHODS: Immunohistochemistry was used to analyze the level of Hcit in skin lesions of seborrheic keratosis (SK), unaffected skin (distant 0.5 centimeters from SK lesion), and normal skin of healthy subjects in the control group. ELISA test was used to detect the serum level of CBL in SK patients and healthy subjects of different ages.
RESULTS: Hcit was mainly localized in the nucleus of epidermal cells. In healthy control skin, the expression of Hcit increased with age and showed a positive correlation with age (the correlation coefficient was 0.806, p = 0.0002). The expressional level of Hcit in SK lesions was higher than that in healthy control skin (Z = -3.703, p = 0.0002). The serum level of CBL in healthy subjects and in SK patients increased with age (the correlation coefficient were 0.5763, p = 0.0032; 0.682, p = 0.004. respectively). The serum level of CBL in SK patients was higher than that in healthy subjects (Z = -2.19, p = 0.030).
CONCLUSIONS: The small serum sample size in the study.
CONCLUSIONS: The high expressional level of Hcit is correlated with seborrheic keratosis and skin aging. HCit may be one of the potential biomarkers of skin aging.

BACKGROUND: Currently, most studies of ELAV (Embryonic Lethal, Abnormal Vision, Drosophila)-like protein 4 (Hu antigen D, HuD) focus on nervous system-related diseases; the role of HuD in the occurrence of skin aging and seborrheic keratosis (SK) has not been reported.
OBJECTIVE: To explore the role of HuD in the occurrence of SK and skin aging and its related clinical significance.
METHODS: The expression levels of HuD in the skin and blood of healthy people at different ages, SK lesions, and perilesional skin of SK patients were detected by both immunohistochemistry and Western blotting. The mRNA expression levels of HuD in the skin and blood of healthy peoples at different ages were detected by quantitative real-time reverse transcription-polymerase chain reaction. The expression level of HuD was compared with the skin of healthy people, SK lesion, and perilesional skin of SK patients of the same age.
RESULTS: The immunohistochemistry and Western blotting showed that the expression levels of HuD in SK lesions were higher than those in healthy skin and perilesional skin. The immunohistochemical staining intensity, protein and mRNA expression levels of HuD in the skin and blood of healthy people were correlated with age, which gradually increased with increasing age.
CONCLUSIONS: HuD is highly expressed in SK lesion and aged skin, indicating that a higher HuD expression level is correlated with occurrence of SK and aging skin; however, its mechanism needs to be further studied.

BACKGROUND: Molluscum contagiosum (MC), milia, keratosis pilaris (KP), verruca plana (VP), seborrheic keratosis (SK), and juvenile xanthogranuloma (JXG) are common papule dermatoses on the face of children that have a similar appearance. In vivo evaluation of facial papule dermatoses with reflectance confocal microscopy (RCM) is helpful in the diagnosis of these ambiguous lesions in children. The purpose of this study was to clarify the RCM characteristics of MC, milia, KP, VP, SK, and JXG and explore the clinical application value of RCM for these common facial papule dermatoses.
METHODS: We recruited 113 patients referred for unequivocal facial papule dermatosis, including 21 patients with MC, 17 patients with milia, 19 patients with KP, 36 patients with VP, 8 patients with SK, and 12 patients with JXG. We evaluated the characteristics and distinguishing features of the six kinds of facial papule dermatoses using RCM.
RESULTS: The main RCM features of the six dermatoses included a well-demarcated border of the lesion area. MC, milia and KP all manifested cyst-like structures, and their distinguishing features were the location of the cystic structures and the refractive index of the contents. Although VP, SK, and JXG did not have obvious cystoid structures, VP was typically characterized by uniformly distributed petal-like structures with a medium-to-high refractive index in the epidermis. With regard to SK, the characteristic features were an obviously thickened epidermis and cobblestone-like structures. JXG was mainly characterized by multiple large round and ovoid cells with a foamy cytoplasm, and discoid-shaped multinucleated large cells were diffusely distributed in the dermis.
CONCLUSIONS: RCM allows the real-time visualization of major key diagnostic and distinguishing features of common facial papule dermatoses in children, including MC, milia, KP, VP, SK, and JXG.

UNASSIGNED: The aim of this study was to describe the clinical and histopathological characteristics of seborrheic keratosis (SK) with secondary tumor and identify associated factors.
UNASSIGNED: This study was a monocentric retrospective case-control study describing the factors associated with the development of tumors in SK. A total of 1365 patients with SK were admitted to our department between 2018 and 2021. All of the histopathological specimens and medical records of these patients were reviewed. We compared the data of 36 patients with tumors arising in SK with those of the remaining 1329 patients with only SK, which were designated the control group.
UNASSIGNED: The incidence of tumors arising in SK that were biopsied was 2.6%. The tumor types included squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and keratoacanthoma (KA). Compared with other patients with SK, elderly patients with immunosuppression, patients presenting surrounding erythema or ulceration, and those with SK in exposed areas had an increased possibility of developing a secondary tumor. Tumors arising within SK have the histopathological features of ulceration, cytologic atypia, mitosis, \"malignant horn\", trabecular cell cords, solar elastosis and severe inflammatory infiltration in the dermis.
UNASSIGNED: SK can show malignant progression in a small fraction of SK cases that are biopsied. This study is the first report on the clinical and histopathological characteristics of tumors arising in SK and identifies relevant factors in an Asian population.

Seborrheic keratosis (SK) is a common benign lesion in which malignancies like cutaneous squamous cell carcinoma (cSCC) can arise rarely. We report a case of an 81-year-old man who presented a well-demarcated reddish-brown plaque with central raised coarse nodules on the top of his head. Dermoscopy and reflectance confocal microscopy (RCM) showed the possibility of malignant transformation. cSCC was confirmed by histopathology and immunohistochemistry. Considering the fact of local low-risk cSCC within a large SK lesion, carbon dioxide (CO2) laser was used to treat the SK lesion, and reduce the thickness of local cSCC simultaneously. Three sessions of 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) were performed after CO2 laser. Finally, no atypical cells were found by multi-point biopsy after treatment, and follow-up was continued for one year. Therefore, malignant changes of SK are relatively uncommon, but should be suspected when abnormal appearance or symptoms occurred. ALA-PDT combined with CO2 is a safe, effective, and minimally invasive treatment for cSCC arising from a huge SK.

BACKGROUND: Basal cell carcinoma (BCC) is the most common cutaneous malignancy. Occasionally, it may have an appearance similar to that of some benign pigmented skin lesions. Therefore, additional information is needed to differentiate these lesions.
METHODS: A diagnostic accuracy study was performed from February 2018 to April 2019. All lesions underwent ultrasound examination with 50 and 20 MHz probes. The high-frequency ultrasound (HFUS) images were evaluated independently by 2 experienced doctors for the presence of predefined features, including the depth, shape, margin, anechoic area, hyperechoic spots, epidermal interrupted echo, mushroom sign, flat-bottom sign, and superficial hyperechoic focus (SHEF).
RESULTS: A total of 54 BCCs, 51 melanocytic nevi and 55 seborrheic keratoses (SK), were included. BCCs often involved the subcutaneous tissue (11/54, 20.4%; P < .001) and had an irregular shape (26/54, 48.1%; P < .001) and ill-defined borders (26/54, 48.1%; P < .001), while most benign pigmented lesions had a regular shape (101/106, 95.3%; P < .001) and well-defined borders (95/106, 89.6%; P < .001). BCCs occasionally showed anechoic areas (10/54, 18.5%; P < .001) and epidermal interrupted echo (18/54, 33.3%; P < .001). Moreover, hyperechoic spots could be found in BCCs (43/54, 79.6%), nevi (27/51, 52.9%), and SK (30, 54.5%) (P = .001), with mean number of 7.3, 5.5, and 8.0, respectively. The mushroom signs were all present in melanocytic nevi (18/51, 35.3%), while the flat-bottom sign (43/55, 78.2%; P < .001) and SHEF (40/55, 72.7%; P < .001) presented mainly in SKs.
CONCLUSIONS: Based on the typical features, HFUS could improve the accuracy of BCC identification and should be considered when dermatologists are unsure about the lesion type.