Treatments are challenging in generalized granuloma annulare. We reported two cases of generalized granuloma annulare without diabetes mellitus; one exhibited non-annular papules and the other did patch/annular lesions. Since they were refractory to multiple treatments, we treated them with JAK inhibitor baricitinib at 2 mg daily. After 1–2-month treatment, they responded well to baricitinib with good tolerance. Given increased JAK1 signaling, high interferon-α and -γ production and macrophage activation in granuloma annulare, JAK inhibitors are considered to be a reasonable choice for recalcitrant generalized granuloma annulare. In addition to the reported cases, our two cases further support the effectiveness of JAK inhibitors for generalized granuloma annulare.

An identical group of disorders has been called “interstitial granulomatous dermatitis” and “palisaded neutrophilic and granulomatous dermatitis.” In addition, a drug-induced subset of this condition has been named “interstitial granulomatous drug reaction (IGDR).” More recently, “reactive granulomatous dermatitis (RGD)” has been proposed as an umbrella term encompassing these three disorders. A considerable number of RGD cases are associated with systemic conditions, including autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus, inflammatory bowel disease, and malignancies. IGDR has also been shown to be caused by certain medications. We present a case of a 74-year-old Japanese man showing an asymptomatic, well-demarcated erythema eruption on the bilateral inguinal region extending to the lower abdomen and proximal thigh area. He had hyperlipidemia and had been taking pravastatin for 4 years. A biopsy specimen taken from the erythematous lesion revealed infiltration of lymphocytes and histiocytes in the upper and lower dermis. Interstitial infiltrates of histiocytes and lymphocytes were found as they were dispersed between collagen bundles. Immunostaining showed CD68+ macrophages intermingled with CD4+ and CD8+ T cells. Based on the clinical and histologic findings, the eruption was diagnosed as RGD. Because of the possibility of IGDR, pravastatin was stopped. His eruption completely disappeared within 6 months after the discontinuation. The list of drugs that cause RGD includes angiotensin-converting enzyme inhibitors, antihistamines, β-blockers, antidepressants, anticonvulsants, tocilizumab and ustekinumab. In addition, various statins have been reported to induce drug eruptions. The eruption types are mainly eczematous or lichenoid reactions, with psoriasiform or ichthyosiform reactions occurring rarely. There was only one report documenting that RGD occurred in patients administered rosuvastatin, with annular, violaceous plaques distributed on the extremities, proximal trunk and intertriginous areas. Pravastatin induces lichenoid eruption, but RGD has not been documented. Our case suggests that RGD is underestimated as an adverse effect of statins possibly because of its unusual cutaneous manifestations.

Eczema is the most common category of inflammatory skin disorders as dermatologists see many patients with eczematous diseases in daily practice. It is characterized by the three major morphological features: multiple-pinpoint condition, polymorphism, and itch. To describe polymorphism, "eczema triangle" has been used in German/Japanese dermatology. The multiple pinpoints correspond to numerous tiny foci from which individual papules/vesicles arise. The polymorphism betrays composition of erythema, papule, seropapule, vesicle, pustule, scale, and crust, which are seen in acute eczema. Meanwhile, chronic eczema is represented by lichenification and hyperpigmentation, and possibly by hypopigmentation. In acute eczema, spongiosis is associated with overproduction of hyaluronic acid, secretion of self-protective galectin-7, and decreased expression of E-cadherin. In the upper dermis, Th1/Tc1 or Th2/Tc2, and additional Th17, Th22, and/or Tc22 infiltrate, depending on each eczematous disease. Innate lymphoid cells are also involved in the formation of eczema. In chronic eczema, periostin contributes to remodeling of inflammatory skin with dermal fibrosis, and epidermal melanogenesis and dermal pigment deposition result in hyperpigmentation. Finally, eczematous diseases are potentially associated with increased risk of comorbidities, including not only other allergic diseases but also coronary heart disease and mental problems such as depression. Although the original word for eczema is derived from old Greek "ekzein," eczema remains a major target of modern science and novel therapies.

Since atopic dermatitis (AD) is a heterogeneous condition, subtyping of AD is a crucial issue. The classical subtypes of AD are represented by extrinsic and intrinsic subtypes, European American and Asian subtypes, and adult and pediatric subtypes. While subtyping of AD was historically conducted based on the phenotype, recent findings on the mechanisms of AD have revealed importance of the endotype, which can characterize individual patients more accurately. Considering the current development of AD therapies, AD endotyping is prerequisite for personalized therapeutic choice. Endotypes of AD can be stratified from different viewpoints, including cytokine expression patterns, allergen properties, epidermal barrier conditions, ceramide variation, involvement of innate immunity, and serum biomarkers. Among them, the cytokine-based endotype seems to be the most useful one and is categorized into type 2 cytokine (IL-4, IL-13 and IL-31)-high, type 1 cytokine (interferon-g)-high, and/or type 3 cytokine (IL-22 and IL-17)-high, or mixed subtypes. The recently biomarker-proposed endotyping aims at individualized treatment options, although the daily clinical use of endotypes is a future issue. To better understand the endotypes for clinicians, attempts to adjust each of the classical subtypes to the endotypes are required. This review will discuss the correspondence of the classical subtypes to the various endotypes that have recently been proposed.

Since atopic dermatitis (AD) is a heterogeneous condition, the subtyping of AD is a crucial issue. The classical subtypes of AD are represented by extrinsic and intrinsic subtypes, European–American and Asian subtypes, and adult and pediatric subtypes. While the subtyping of AD was historically conducted based on the phenotype, recent findings on the mechanisms of AD have revealed the importance of the endotype, which can characterize individual patients more accurately. Considering the current development of AD therapies, AD endotyping is a prerequisite for a personalized therapeutic choice. Endotypes of AD can be stratified from different viewpoints, including cytokine expression patterns, allergen properties, epidermal barrier conditions, ceramide variation, the involvement of innate immunity, and serum biomarkers. Among them, the cytokine-based endotype seems to be the most useful one and is categorized into type 2 cytokine (IL-4, IL-13 and IL-31)-high, type 1 cytokine (IFN-γ)-high, and/or type 3 cytokine (IL-22 and IL-17)-high, or mixed subtypes. Recently proposed biomarker endotyping aims at individualized treatment options, although the daily clinical use of endotypes is a future issue. To better understand the endotypes for clinicians, attempts to adjust each of the classical subtypes to endotypes are required. This review will discuss the correspondence of the classical subtypes to the various endotypes that have recently been proposed.

Sensitive skin is a well- known skin condition showing sensory irritation to daily used products such as cosmetics or pharmaceuticals, possibly containing sensory irritants. Methylparaben (MP), widely used as a preservative, is a representative sensory irritant and hydrolyzed in the skin. We aimed to clarify the relationship between MP sensory irritation and MP hydrolysis. First, we investigated the percutaneous penetration and hydrolysis of MP by using an ex vivo pig skin system and confirmed that topically applied MP was immediately hydrolyzed to p-hydroxybenzoic acid (PHBA). We next evaluated whether MP or PHBA causes sensory irritation using a well-used stinging test in human skin and found that MP, but not PHBA, induced irritation. Additionally, MP, but not PHBA, increased intracellular calcium in cultured TRPA1-expressed HEK293 cells, supporting the stimulatory activity of MP. Five and 10 individuals with sensitive and non-sensitive skin, respectively, were selected by a questionnaire and stinging test. In their biopsied skin samples, MP hydrolytic activity was significantly lower in sensitive than non-sensitive skin. Finally, we examined the activity of carboxylesterase (CES), which promptly hydrolyzes MP to PHBA. By using specific inhibitors of CES and CES2, we found that CES1 was responsible for MP metabolism. Our study suggests that low skin metabolism of topical agents is one of the causes of skin sensory irritation and resultant sensitive skin.

• Ethyl 3-phenylpropionate; a safety assessment based on RIFM's criteria. • A safety assessment based on 7 human health endpoints plus environmental. • All endpoints were cleared using target data, read-across, and/or TTC.

Pityriasis rubra pilaris (PRP) is a rare, chronic, inflammatory dermatosis characterized by follicular, hyperkeratotic papules and palmoplantar keratoderma at any age. The exact etiology of the disease remains unknown, but it can be triggered by multiple factors and genetic backgrounds. Here, we describe a case of PRP occurring after SARS‐CoV‐2 vaccination. While the vaccination is generally safe, it should be kept in mind that PRP may be evoked by SARS‐CoV‐2 vaccination for early recognition of the cause and prognosis of the patients.

The data supporting this study's findings are available from the corresponding author upon reasonable request.

DiGeorge syndrome, also known as 22q11.2 deletion syndrome, shows cellular immunodeficiency due to by thymic hypoplasia and hypocalcemia caused by hypoparathyroidism. It was reported that erythrodermic psoriasis occurred in a patient with 22q11 deletion syndrome. Here, we report the first case of DiGeorge syndrome presenting with a severe palmoplantar pustulosis (PPP)-like eruption with extra-palmoplantar lesions on the distal limbs. Given that PPP is a subtype of pustular psoriasis, the pustular eruption may be associated with DiGeorge syndrome. We measured serum levels of citrullinated histone H3 (CitH3), a representative marker of neutrophil extracellular traps, interleukin (IL)-8, and IL-22 and compared them with nine cases of typical PPP. In the PPP patients, the three markers were higher than in healthy subjects with significant correlations between CitH3 and IL-8/IL-22. In our patient, CitH3, IL-8, and IL-22 were also high, and IL-22 was remarkably elevated compared with the PPP patients. Our case suggests that a certain T cell abnormality associated with DiGeorge syndrome induces IL-22 overproduction, leading to the PPP-like eruption with extra- palmoplantar lesions.

Hidradenitis suppurativa (HS) is characterized by inflammatory nodules, abscesses and fistulas.Severity can be assessed by several scores requiring detailed, time-consuming and error-prone lesion counts.This study aimed to investigate automated HS-severity classification from clinical images.777 distinct images from 149 patients were taken using smartphones.Images were ambient-light and size-controlled using the Scarletred Ò Vision platform.A convolutional neural network (CNN) was used to predict Hurley grades.A mixed input neural network was trained for a granular representation of disease activity (scale 0-49).A U-NET algorithm was implemented for localization of diseased skin.To solve class-imbalances, a synthetic dataset (n¼7675, 80% training, 20% test) was generated using a data augmentation approach (scaling, normalization, feature engineering).Training CNNs to distinguish no, mild, moderate and severe disease, provided an overall prediction accuracy of 72% (4scale, multiclass) and 78% (binary; no/mild vs. moderate/severe).The receiver operating curves revealed an AUC of 0.85 (binary) and 0.84-0.89(multiclass).The class-wise accuracy for each Hurley grade was calculated with 81-88%.No/mild disease could robustly be distinguished from moderate/severe disease (p<.001).The mixed input model accurately aligned with changes in HS disease activity with a NRMSE value of 0.2618.The UNET algorithm localized HS lesions with a pixel accuracy of 88.1% and test loss of 0.42.The CNNs were able to: 1) Distinguish no/mild from moderate/severe disease, 2) classify disease dynamics over time and 3) identify diseased skin areas.This study breaks new grounds for fast, reliable, reproducible and easy-to-use HS severity assessments.

Atopic dermatitis (AD) is a heterogenous disorder and can be classified into different types. Stratification of subtypes may enable personalized medicine approaches. AD can be categorized into the IgE-high, extrinsic subtype and the IgE-normal, intrinsic subtype. While extrinsic AD is the major subtype possessing skin barrier impairment (high incidence of filaggrin mutations), intrinsic AD occupies about 20% of AD with female dominance and preserved barrier. Extrinsic AD exhibits protein allergy and food allergy, but intrinsic AD shows metal allergy possibly in association with suprabasin deficiency. In particular, accumulated knowledge of food allergy has more clearly characterized extrinsic AD. European American (EA) and Asian AD subtypes have been also proposed. Asian patients with AD are characterized by a unique blended immune dysregulation and barrier feature phenotype between EA patients with AD and those with psoriasis. In another ethnic study, filaggrin loss-of-function mutations are not prevalent in African American patients with AD, and Th1/Th17 attenuation and Th2/Th22 skewing were seen in these patients. Recent endotype classification provides new insights for AD and other allergic disorders. Endotype is defined as the molecular mechanisms underlying the visible features/phenotype. Endotype repertoire harbors activation of type 2 cytokines, type 1 cytokines, and IL-17/IL-22, impairment of epidermal barrier, and abnormalities of intercellular lipids. Classification of endotype has been attempted with serum markers. These lines of evidence indicate a need for personalized or precision medicine appropriate for each subtype of AD.

Recently, the number of dermatologists who pursue scientific research careers has been dwindling in Japan. One of the major reasons for the reduction is the recent alterations of the Japanese medical specialty training system. Our strategies against the decline of young dermatologists’ desire to be physician‒scientists include the establishment of a simultaneous PhD program for specialty course trainees, the establishment of a young academician-fostering seminar by the Japanese Society for Investigative Dermatology, and support for studying abroad by the Japanese Dermatological Association.

Tattoos are used as world-wide cosmetic practice and an exotic self-expression form in some social groups. In the black henna tattoo, to darken the color, it occasionally contains hair dyes, as represented by paraphenylenediamine (PPD)8-10, which is well known as contact allergen. We report an erythematous indurated eruption congruous with a dermally injected permanent tattoo in a patient who had contact dermatitis to PPD.

Melanoma is a malignant skin tumor with high metastatic activity. Although melanoma has been well-studied, its cellular kinetics remain elusive. The cholecystokinin (CCK) receptor is expressed in various types of tumors because CCK promotes the survival and proliferation of tumor cells. Thus, we hypothesized that the growth of melanoma was positively regulated by signals from the CCK receptor and sought to investigate whether CCK receptor antagonists affect the growth of melanoma cells expressing CCK receptor. Immunohistochemically, the CCK receptor A is expressed in the clinical specimens of melanoma. CCK receptor antagonists decreased the viability of melanoma cells by suppressing cell division and promoting apoptosis. CCK receptor antagonists also decreased the mitochondrial membrane potential through enhanced gene expression of the proapoptotic protein, Bcl2-associated X, and tumor suppressor, p53, suggesting that the antagonist induced the apoptosis of melanoma cells in a mitochondria-dependent manner. In addition, a caspase 3 inhibitor, Z-DEVD-FMK, partially blocked the antiviability of the antagonist, indicating that caspase 3 is involved in antagonist-induced apoptosis. Notably, tumor growth was attenuated when a CCK receptor antagonist was locally administered to the melanoma-bearing mice. Therefore, our study suggests the therapeutic potential of CCK receptor antagonists in the treatment of skin cancer.

Adult T cell leukemia-lymphoma (ATL) is clinically heterogeneous and is classified into four subtypes: acute, lymphoma, chronic, and smoldering. Recently, a new prognostic index based on the value of soluble interleukin-2 receptor, denoted the "iATL-PI," has been proposed for patients with smoldering and chronic ATL. To evaluate the effectiveness of the iATL-PI, we re-analyzed our previously published data on 176 patients with smoldering or chronic ATL (76 smoldering, 100 chronic) diagnosed between 2010 and 2011, as well data from the subsequent follow-up study on prognosis between 2016 and 2017. The proportions for the low-, intermediate-, and high-risk iATL-PI groups at the time of ATL diagnosis were 44.7%, 48.7%, and 5% for smoldering ATL; 6.3%, 71.9%, and 21.9% for favorable chronic ATL; and 5.9%, 27.9%, and 66.2% for unfavorable chronic ATL, respectively. The survival of patients with smoldering or chronic ATL as a whole was significantly stratified according to the three iATL-PI groups. Most patients with unfavorable chronic ATL in the low iATL-PI risk group had indolent clinical courses. Our results showed that iATL may become a useful tool to predict the prognosis of smoldering and chronic ATL, which have diverse clinical courses.