Eiichi Morii

The coexistence of extramammary Paget disease and clinically apparent herpes simplex virus (HSV) infection is extremely uncommon, with only two cases previously described in detail. Herein, we present the case of an elderly woman with an extensive vulvar lesion showing concurrent extramammary Paget disease and HSV infection. Triple immunohistochemical staining for cytokeratin 7, cytokeratin 10, and HSV antigen was performed to re‐evaluate the hypothesis that HSV‐mediated fusion between Paget cells and keratinocytes contributes to multinucleated giant cell formation. HSV antigen was detected in both Paget cells and keratinocytes. HSV‐positive multinucleated giant cells displayed a cytoplasmic staining pattern similar to that of keratinocytes, whereas no Paget cell–like cytoplasmic staining pattern was observed. These findings indicate that HSV can directly infect Paget cells and that the multinucleated giant cells in this case were of keratinocytic origin. No definitive evidence of cell fusion—either among Paget cells or between Paget cells and keratinocytes—was observed in the examined sections. However, the possibility of rare fusion events in unexamined tissue cannot be entirely excluded.

Corticotropin-releasing hormone (CRH) induces an increase in growth hormone (GH) secretion in a subset of patients with acromegaly; however, the characteristics of these CRH responders remain poorly defined. 22 CRH responders were retrospectively compared with 43 nonresponders. CRH responders exhibited significantly larger tumors and more frequent visual field impairment than nonresponders, despite comparable baseline GH and insulin-like growth factor 1 (IGF-1) levels, and disease duration. Tumor volume and diameter were positively correlated with the GH increase ratio in CRH test, whereas GH and IGF-1 per tumor volume or diameter were significantly lower in CRH responders, indicating reduced GH secretory capacity relative to tumor size. Immunohistochemical analyses revealed higher corticotropin-releasing hormone receptor 1 (CRHR1) and lower CRHR2 expression in CRH responders. In addition, T-box transcription factor (TPIT) and adrenocorticotropic hormone (ACTH) expression were significantly more frequent in adenomas from CRH responders, suggesting a corticotroph-like phenotype. GH responses to CRH were significantly correlated with those to luteinizing hormone-releasing hormone but not thyrotropin-releasing hormone or oral glucose tolerance testing. GH responses to CRH tended to be inversely correlated with somatostatin receptor subtype 2 expression as a predictor of first-generation somatostatin receptor ligand efficacy but not with octreotide response or MRI signal intensity. These findings support that GH responsiveness to CRH identifies a biologically distinct subset of somatotroph adenomas characterized by corticotroph-like features, larger tumor size, and reduced GH secretory capacity. GH responsiveness to CRH may serve as a noninvasive indicator of intrinsic tumor biology and behavior.

Purpose: Oral carcinoma cuniculatum (CC) is a rare variant of oral squamous cell carcinoma (OSCC), characterized by a well-differentiated, burrowing invasive pattern and minimal cellular atypia. Its diagnosis is challenging owing to its bland morphology, which makes differentiation from non-neoplastic lesions difficult on biopsy. Despite this, CC often requires distinction from conventional OSCC, even in surgical specimens. Histological overlap with conventional OSCC suggests a continuous spectrum of diseases. To clarify the genetic identity of pure CC, we analyzed 23 cases of OSCC with burrowing invasive patterns and classified them into three groups: CC, conventional OSCC (SCC), and uncertain CC (UCC). Methods: We retrospectively reviewed 2002 OSCC cases from multicenter archives. From this cohort, 23 cases exhibiting a burrowing invasive pattern characteristic of CC were selected. The cases were classified into the three study groups based on the WHO diagnostic criteria, and clinicopathological features were reviewed. Targeted next-generation sequencing was performed to identify clinically significant genetic alterations, and immunohistochemical staining was also conducted. Results: The 23 cases were histologically classified into CC ( n = 8), UCC ( n = 7), and SCC ( n = 8) groups. Clinically, the CC group predominantly affected the gingiva with no recurrence or metastasis. Conversely, the SCC group primarily involved the tongue and showed recurrence and metastasis. Genetic alterations were detected in 87.5% (7/8) of CC cases, with low frequencies of TP53 (12.5%) and CDKN2A (25.0%) alterations and higher frequencies of FAT1 (50.0%), NOTCH1 (37.5%), PIK3CA (37.5%), and CASP8 (50.0%) alterations. In contrast, the SCC group showed frequent TP53 (75.0%) and CDKN2A (75.0%) alterations, whereas FAT1 and NOTCH1 alterations were absent. Consistent with these findings, p53 staining revealed wild-type patterns in the CC group along with a lower Ki-67 labeling index. The UCC group exhibited intermediate clinicopathological and genetic characteristics. Conclusion: This study provides the first genetic characterization of oral CC, distinct from that of conventional OSCC. This genetic signature may contribute to the biological behavior of CC and offer a potential tool for its differential diagnosis. Further studies with larger cohorts are required to confirm the relationship between CC and conventional OSCC, and to fully elucidate the genetic landscape of CC.

Idiopathic pulmonary fibrosis (IPF) is driven not only by fibroblast activation but also by the loss of epithelial identity of alveolar type II (AT2) cells. In fibrotic regions of IPF lungs, AT2 cells frequently transition into KRT17-positive alveolar-basal intermediate cells; however, the intracellular mechanisms that regulate this fate change remain poorly understood. Although transforming growth factorβ1 (TGFβ1) signaling is a major driver of epithelial remodeling, the regulatory pathways that counterbalance this process in AT2 cells have not been clearly defined. Here, we investigated the interaction between the Rho-associated coiled-coil containing protein kinase (ROCK) pathway and TGFβ1 signaling using human distal lung-derived alveolar organoids and human IPF lung tissues. ROCK activity was assessed by phosphorylated ezrin/radixin/moesin (pERM), a marker of ROCK pathway activation, whereas TGFβ signaling activity was evaluated by phosphorylated Smad2 (pSmad2). Under basal conditions, AT2 organoids displayed strong pERM expression with minimal pSmad2 activation. TGFβ1 stimulation induced trans-differentiation toward a KRT17-positive alveolar-basal intermediate cells accompanied by loss of Surfactant Protein C (SFTPC) expression. Inhibition or knockdown of ROCK markedly enhanced this TGFβ1-induced transition, whereas ROCK activation suppressed it. Consistently, human IPF tissues showed pERM-positive/pSmad2-negative AT2 cells in non-fibrotic regions, while fibrotic regions were enriched with pSmad2-positive/pERM-negative alveolar-basal intermediate cells. These findings identify ROCK signaling as a key mechanism that preserves AT2 cell identity and antagonizes TGFβ1-driven epithelial remodeling, suggesting epithelial ROCK activity as a potential therapeutic target in IPF. Our findings establish ROCK signaling as a gatekeeper of AT2 cell identity during fibrotic lung remodeling.

The mammalian brain comprises numerous anatomical regions with distinct functions despite their extensive connectivity. How spontaneous neural activity is coordinated across regions over the circadian cycle remains elusive. We used tissue clearing and whole-brain c-Fos immunostaining on 144 mouse brains collected over 2 days under constant darkness. Time-series analysis revealed brainwide circadian rhythmicity at single-cell resolution, with 79% of the 642 anatomically defined regions oscillating in diverse circadian phases that delineate functional specializations. Voxelwise analyses further highlighted distinct subregions, suggesting intricate spatiotemporal coordination within regions. Additionally, brain circadian time could be accurately inferred from global c-Fos patterns using omics-derived prediction methods. This whole-brain circadian atlas enhances our understanding of neural coordination and provides a resource for integrating time-of-day information into functional and pharmacological research.

Background: Gastric-type adenocarcinoma (GAS) of the uterine cervix is a rare malignancy with poor clinical outcomes. However, the carcinogenic processes involved remain unclear. Methods: Normal cervical glands, lobular endocervical glandular hyperplasia (LEGH), and GAS from the same patients were collected using laser microdissection for whole-exome sequencing. Single nucleotide variants (SNVs) and copy number alterations (CNAs) were analyzed. Phylogenetic trees were constructed based on the SNV and CNA profiles. Results: Analysis of seven matched samples demonstrated higher frequency of somatic mutations in the exonic regions in GAS than in LEGH. CNAs were prevalent in GAS but rare in LEGH. The phylogenetic analyses revealed various branching patterns. However, in three cases, the data suggested a sequential transition from LEGH to GAS, potentially associated with mutations in receptor-type protein tyrosine phosphatases such as PTPRF and PTPRT. STK11 and ARID1A mutations were present in LEGH, with an increased variant allele frequency observed in GAS. In contrast, SMAD4 and SMAD2 showed frequent loss-of-function–type alterations in GAS, including copy-number loss, but were not detected in LEGH. Conclusions: These findings provide insights into the genomic landscapes of LEGH and GAS and suggest potential molecular markers for this transition, which may inform future diagnostic and therapeutic research.

Background: Thrombi follow various natural courses. They are known to become harder over time and may persist long term; some of them can also undergo early spontaneous dissolution and disappearance. Hindering thrombus stability may contribute to the treatment of thrombosis and the prevention of embolisms. However, the detailed mechanisms underlying thrombus maturation remain unclear. Methods: We compared the RNA expression in 3 thrombi retrieved from cerebral vessels via thrombectomy with that in simultaneously sampled blood. The results were validated using immunohistochemistry on 66 thrombi retrieved from patients with cerebral embolism. Single‐cell RNA sequencing data of thrombi from pulmonary arteries were used to uncover the molecular mechanisms. Results: A total of 1121 genes were upregulated in thrombi. Pathway enrichment and protein–protein interaction analyses revealed upregulation of extracellular matrix formation and identified SPP1 as a hub gene. Immunohistochemistry revealed that expression level of osteopontin (the transcript of SPP1 ) positively correlated to that of collagen type VI in thrombi. Osteopontin was expressed primarily by monocytes/macrophages in the thrombi, particularly in older ones. Among these 66 patients, the presence of collagen type VI in the thrombus was marginally associated with longer puncture‐to‐reperfusion time and more passes before reperfusion, indicating that those thrombi were resistant to thrombectomy. Single‐cell RNA sequencing of thrombi identified a subpopulation of monocytes/macrophages that highly express SPP1 . These SPP1 ‐high monocytes/macrophages highly expressed genes related to the extracellular matrix and communicated closely with fibroblasts. Conclusions: Collectively, our findings indicate that SPP1 ‐high monocytes/macrophages play a crucial role in thrombus maturation.

Congenital vascular malformations, affecting 0.5% of the population, often occur in the head and neck, complicating treatment due to the critical functions in these regions. Our previous research identified distinct developmental origins for blood and lymphatic vessels in these areas, tracing them to the cardiopharyngeal mesoderm (CPM), which contributes to the development of the head, neck, and cardiovascular system in both mouse and human embryos. In this study, we investigated the pathogenesis of these malformations by expressing Pik3ca ^H1047R in the CPM. Mice expressing Pik3ca ^H1047R in the CPM developed vascular abnormalities restricted to the head and neck. Single-cell RNA sequencing revealed that Pik3ca ^H1047R upregulates Vegf-a expression in endothelial cells through HIF-mediated hypoxia signaling. Human samples supported these findings, showing elevated HIF-1α and VEGF-A in malformed vessels. Notably, inhibition of HIF-1α and VEGF-A in the mouse model significantly reduced abnormal vasculature. These results highlight the role of embryonic origins and hypoxia-driven mechanisms in vascular malformations, providing a foundation for the development of therapies targeting these difficult-to-treat conditions.