Panfolliculoma (PF) is an uncommon benign follicular neoplasm exhibiting differentiation toward all components of a hair follicle. Several pathologic manifestations have been described in a limited number of cases. We studied 19 cases of PF to summarize the clinical parameters and to classify this unique neoplasm histopathologically. A study of the largest sample series of PF has been performed here. The lesions affect both genders after age 20. The head is the most common site of PF of all types. On microscopic examination, all cases demonstrated advanced follicular differentiation by showing cell components of infundibulum, isthmus, stem, bulb, and mesenchymal papilla. Based on the findings and various patterns in histopathology, we classified PF into 3 subtypes: nodular, superficial, and cystic. The superficial and cystic variants account for most of the cases in our study. The histopathologic differential diagnosis is also discussed for each subtype.

Mammary and extramammary Paget’s Diseases (PD) are a malignant skin cancer characterized by the appearance of Paget cells. Although easily diagnosed, its pathogenesis remains unknown. Here, single-cell RNA-sequencing identified distinct cellular states, novel biomarkers, and signaling pathways — including mTOR, associated with extramammary PD. Interestingly, we identified MSI1 ectopic overexpression in basal epithelial cells of human PD skin, and show that Msi1 overexpression in the epidermal basal layer of mice phenocopies human PD at histopathological, single-cell and molecular levels. Using this mouse model, we identified novel biomarkers of Paget-like cells that translated to human Paget cells. Furthermore, single-cell trajectory, RNA velocity and lineage-tracing analyses revealed a putative keratinocyte-to-Paget-like cell conversion, supporting the in situ transformation theory of disease pathogenesis. Mechanistically, the Msi1-mTOR pathway drives keratinocyte-Paget-like cell conversion, and suppression of mTOR signaling with Rapamycin significantly rescued the Paget-like phenotype in Msi1-overexpressing transgenic mice. Topical Rapamycin treatment improved extramammary PD-associated symptoms in humans, suggesting mTOR inhibition as a novel therapeutic treatment in PD.

Smoking has been identified as a risk factor for atopic dermatitis and hand eczema, but less is known about the association of exposure to second-hand smoke (SHS) with hand eczema. The study aimed to investigate the association of SHS exposure with hand eczema and atopic dermatitis in a group of adolescents. We conducted a cross-sectional study among first-year college students. SHS exposure was measured by a self-administered questionnaire. Skin diseases were diagnosed by dermatologists in the field survey. Mixed models were used to estimate the associations. A total of 20,129 participants that underwent skin examination and a questionnaire survey were included in the analyses. The prevalence rates of atopic dermatitis and hand eczema were 3.86% and 3.35%, respectively. Crude and adjusted estimates consistently showed that exposure to SHS was significantly associated with atopic dermatitis and hand eczema in a dose–response manner. Attention deficit/hyperactivity disorder mediated minimal or no effect of SHS on hand eczema and atopic dermatitis. Subgroup analysis by type of hand eczema, and sensitivity analysis by excluding data with center effect showed consistent results. Exposure to SHS is an independent but modifiable risk factor for hand eczema and atopic dermatitis in adolescents.

Sclerosing lipogranuloma is a granulomatous reaction to the injection of a high-viscosity fluid in the tissues for the cosmetic purpose of improving body contour; lesions on the extremities and buttocks are commonly the results of injections of therapeutic agents in oily vehicles. Exenatide, once-weekly injection, is a therapeutic method for patients with type 2 diabetes. Here, we describe a case of exenatide once weekly induced eosinophilic sclerosing lipogranuloma at the injection site of a 62-year-old patient. To the best of our knowledge, the histopathologic features of this adverse event have not been reported in the medical literature.